gudge

Although your issue was the pressure relief valve (good information for me to validate some of my knowledge about the fuel system). I wanted to share for you and others, that I have had "3" successive pressure sensor failures (over a period of 3.5 years), which the first one and third one were fairly straight forward; they failed low or open. The symptom was the engine stopped running (even at highway speed with no forewarning) and there is no start function at all, dead. I spent a lot of time troubleshooting and understanding the fuel feed steps/process/design/control to finally rule out the fuel feed i.e., starting from the gas tank all the way to the fuel injectors (including the computer inputs/outputs), and was down to two sucpect components - the FCA and/or the Fuel Rail Sensor ( i wrote in detail about my troubleshooting which you may be able to look up., which explains how i ruled out the FCA). The second failure was much more troubling to understand and diagnosis, but it was that the fuel pressure sensor had failed high or erratic, which caused the engine to surge, smoke, major loss of power, and not being consistent between these symptoms. But again it was the fuel rail pressure sensor! In fact, this started in 2015, followed by second failure (high dollar replacement part) in less than a year, followed by the third failure of a $25 bosch fuel rail pressure sensor off of eBay when it failed with approximately 10,000 miles and 1.5 years of operation. The last failure (recently) did give me forewarning however by the engine becoming hard to start (i had to over crank the engine to get it to start and not run ruff) and it would run a little ruff and smoke a little too until it warmed up. This hard to start or having to overcrank during starting actually was a very distinct and notable change that occurred and consistently continued for about 3-4 thousand miles before final failure (btw we took two long distant trips during this time). Luckily, ever since the second failure (the huge headache failure), I have been carrying a socket and ratchet with a spare fuel rail sensor in the truck and another spare sensor in the shop (ebay $25 ones). This was smart since the third failure left my wife on side of road with horses in trailer, which I only had to drive out and meet her and just simply change out the sensor (since the signature symptom was that she lost power (again) at highway speed, and this was all I needed to know to immediately target the sensor). When the sensor fails low or open, this is a significant reliability part issue with this diesel engine that leaves you on the side of the road (luckily I did not incur the significant costs of letting someone else "touch" my truck!). Hope this helps; also try googling my previous post(s) of my troubleshooting details on the fuel system operation when I was learning about this for the first time (i.e., my first diesel engine truck). I wanted to share this information since it can be perplexing when your in the middle of figuring out your problem. Good luck and keep us posted.

Thanks - cheers all the way around; these man made machines are a blessing and a curse at times! I was a Navy ET (many years ago with tube/transistors) and have held an Extra Class Ham license ever since, fiddled with avionics, antennas, etc... but it is always a challenge that keeps me perplexed most of the time - like flying in the clouds until you breakout into sunlight. I can't deny it being worth celebration over a beer or two though. Now on to working with Bosch via US Diesel Parts guys to refund me the part cost under its warranty and believing maybe improving the parts reliability. This RPS only lasted 4K miles over a 6 month period?

Success Proclamation: Problem Fixed!!! ...Eureka Ok, I see this clearly now Angus, which my troubleshooting was driving me to understand the sensor operation more in detail in order to test the Rail Pressure Sensor correctly for confirmation of failure. My troubleshooting had shifted toward this component (others can see from the above steps, analysis, questions, and thoughts - thanks to all) as the root cause of my truck shutting down while driving at 60 mph on cruise control with NO symptoms, NO engine light, NO noises, No electrical perturbations, NO nothing, but silence while coasting to a stop at night and then essentially a crank/no start condition. Well, I tested all three Rail Pressure Sensors (RPS) by connecting them to the ECM via the normal connector (uninstalled) and took the voltage reading from the center connector (Fuel Rail Sensor Signal). I found where Bosch/Cummings provided the signal expected output from the RPS to the ECM (i.e., .5 vdc - 4.5 vdc for a corresponding 0 psi - 26,107 psi) so this allowed me to know what I was looking for from each of the three sensors: the original failed low (P0192 code) sensor which should be very low/no voltage output; the existing failed high (P0088 code) sensor which should be a much higher than .5 vdc output; and, the new sensor just recieved which should be .5 vdc at 0 psi if it is working properly without any problems). The results of the data acquired were almost precisely what would be expected for each condition: The original failed low sensor (P0192 code) output measured .01 vdc The existing failed high sensor (P0088 code) output measured 2.84 vdc (this output corresponds to approximately 15,000 psi fuel rail pressure) The new sensor output measured .5 vdc as it is designed and specified to provide for 0 psi These measurements were all expected based on my troubleshooting narrowing down that the RPS had failed, not the FCA, not the COV, not the ECM, etc...!!!!!! It can be easily seen that the measured outputs correspond to the failure codes received, and the new sensor output is as specified (EXACTLY) by the manufacturer. In retrospec, the initial codes that I got (P02509 and one for low intake voltage/#?) were misleading, and I may have caused them via trying to trouble shoot on the side of highway and/or possibly due to my weak/8 yo batteries? But after reading these codes, and then clearing them the next morning with my code reader, they never returned again thru all my other troubleshooting, ...and then when I finally stumbled on to being able to start the truck and initially get it to run although only for a brief period (i.e., from the ACC ign. sw. position), the p0088 code has been central to all the other start/run configurations since (except when the RPS is disconnected from ECM as would be expected). However, I still can not answer why the truck would not start/run from the On ign. sw. position, but would start/run and then die from the ACC ign. sw. position? I believe now it was the ECM shutting down/cutting off fuel from the fuel injectors (i.e., no fuel allowed to enter cylinders) with the overpressure signal (i.e., from the failed RPS), since because from what has been learned about the FCA when its valve is seated fully closed by spring pressure (i.e., the solenoid is not operating/ECM demanding less fuel rail pressure) there should have been enough fuel emitted (i.e., the FCA valve seated fully closed by spring pressure would still allow idle fuel flow to the CP3 due to the small end of the triangular shaped valve opening "always" allowing idle fuel flow when the FCA valve is fully seated closed -see excellent web page link above with pictures of FCA internals). Other important learnings are that the truck would start/run with the FCA disconnected, and it would also start/run with the RPS disconnected from the ECM, an important future trick to use and limp yourself home! If I had this knowledge that "dark" night, it would have potentially allowed me to run/limp the truck home without tow ...I did not test moving the truck during my troubleshooting in these configurations so this can not be affirmed but there was a steady idling engine, and if I remember correctly there was throttle capability at least with the RPS disconnected. Additionally, the COV was a potential issue and could have been a strong suspect, but it is very easily troubleshot by removing it and mechanically inspecting its operation ( i.e., by pushing valve its length of travel (smoothly) with a small diameter shaft). Lastly, the FCA is really just a very simple solenoid device/mechanical valve and its testing can be determined by operating it in hand while connected to the ECM (it also throws codes that should help with identifying its failure). I hope all this recap helps others for now and while I got the family back on the road pulling horses around, as time permits I will try to get my notes and diagrams ironed out for posting. These should top-off this whole episode as my final sign-out. Lastly, thank you to all for your inputs and thoughts, which have helped educate me into becoming a diesel troubleshooter or at least allowed me to grow knowledge and have an appreciation for the all mighty diesel engine design and operation! Please feel free to correct me on anything that is not correct or could use clarifications, as these posts are meant to help others ...and that may well mean me again, too!??

Received the new Rail Pressure Sensor from US Diesel Parts Monday evening, and started trying to obtain static measurements. After a little while of getting mixed results, I started researching the sensor operation and determined the continuity checks do not provide any useful information (Sensor operation is based on piezio crystal converting pressure to voltage - I believe to be correct by deduction of studying the diagrams, electrical prints and reading operation description). It appears I need to connect it to the computer and take voltage readings and/or ground readings. Therefore, I will test all three Rail Pressure Sensors connected to the ECM to get the failure data from the two and the good data from the new sensor. There are three leads with the sensor: a 5vdc reference, a ground (from ECM), and a variable voltage output based on pressure. I will test it at zero pressure (which should correlate to .5 vdc output). Hopefully, truck will be back in service this week end and share the data for each sensor (i.e., the failed low one, failed high one, and the good sensor).

I would agree, it is now cataloged well within my memory. I believe you could do the same for the FCA too. Ed, it is all about learning for me since I don't have much experience with diesel engines, much less Cummins. I appreciated your help!

Thanks, I thought there may be a code set for this type of failure. This rules out my situation, but I checked the wiring closely for the benefit of knowing its condition.

I called US Diesel Parts where the pressure sensor was purchase in May 2014 and discussed the warranty for the premature pressure sensor failure. They were helpful and let me know that it should be covered, but it will have to be sent back to Bosch for failure verification and warranty processing. Based on them giving me this assurance and not being able to wait the number of weeks all this is going to take, I went ahead and ordered the new pressure sensor. US Diesel Parts will then reimburse me the cost of the new part when Bosch verifies the failure. I would like to believe that Bosch will use this data in the betterment of the next generation of pressure sensor parts for improved reliability and in the end, all of us diesel customers may benefit (one day?). However, I look forward to taking the continuity readings on the new pressure sensor for critical baseline data that will help the rest of us NOW, as an effort to greatly improve the efficiency of diesel troubleshooting and testing for sensor failures!.

Ok, I will do this for use with others to troubleshoot the sensor in a static mode - sure will help verify than trial and error approach most of us if not all have to perform along the way.

Well, troubleshooting today determined that the COV is operating correctly, fuel flow verified to flow from CP3 while cranking, and so I removed COV for inspection. The piston slides smoothly under constant spring pressure, no hang ups or limited travel issues. So my focus shifted to the fuel rail pressure sensor since it is producing the only (P0088) code. I unplugged the sensor and tried starting the truck, which it started with no problem - although it was running rough (to be expected), and I got a P0192 code, "Fuel Rail Pressure Sensor Low". So to recap: I can start the truck from ACC ign. sw. pos., but engine dies (get a P0088 code); I can start engine with FCA disconnected (get P0088 and P0251 codes); and, I can start engine with fuel rail pressure sensor disconnected (only get a P0192 code and no P0088 code (very interesting!)). Since I have tested the FCA and determined it is good (and the old FCA too), I believe the problem lies with the Fuel Rail Pressure Sensor. I still had the previous failed pressure sensor that I replaced in May this year (due to rough running, surging, no power when driving - P0192 code). So I reinstalled the old failed sensor and with the FCA connected started the engine with no problem and of course got the expected P0192 code and no P0088 code. So my conclusions are that the new Pressure Sensor has failed-high, hence why I can not start engine with FCA connected and when I do start engine I am getting a P0088 code all the time. Therefore I believe the new Pressure Sensor has failed - high. I decided to take continuity readings of both pressure sensors: the fail - low one has no continuity across any of the three connectors (makes sense since it gives a P0192 code, as well as I get this code when starting/running engine with the pressure sensor disconnected); and, the newer pressure sensor has a continuity reading of approximately 35 Ohms across the 2nd and 3rd connector stabs when looking at the end of the connector with the ***/key side upward. Therefore, I plan to check on whether my newer pressure sensor is under a warranty (premature failure) and/or make a purchase of another replacement rail pressure sensor. I will post the final verification that this is the fix to my problem, and also try to share some of my drawings then too.

Ed, Thanks for offer but that link I provided ( Relentless Diesel • View topic - DIY CP3 Mods ) has pictures of how the internals of the FCA look and sequenced into its housing, which I was able to deduct valve positions when energized verse de-energized - super helpful. It does throw a wrench into things about why the engine runs with FCA disconnected and does not shutdown verses starting/running the engine from ignition sw ACC position as you and I discussed previously that the engine shutsdown within 5 or so seconds? What is going on that makes this difference? It may not matter much other than I would like to understand what is going on, but I do believe your suggestion that the COV is the issue does make sense, as I do get the P0088 code during both starting condition (i.e., FCA connected and FCA not connected). So this week end I am looking downstream at the COV and return fuel flow. The only other inputs to cause the no start are other sensor inputs to the ECM, all of which I can not understand why they would not throw their own code, and cause a P0088 code too??? Hopefully, all this logic nails the COV being the failure, and I got the new COV part in the mail along with the fuel injector line blocking tool, and two banjo bolts (one with a gauge connection tap) and the banjo washers you suggested I have on hand to reseal any banjo bolts being removed. I will at least have some more data to ponder .... or a smoking gun!! I will post the results after working on it as I am planning on it tommorrow.

All, ok I am back with additional input; I got tied up for the weekend with family activities but managed to do some of the troubleshooting with the FCA side of my plan. I determined that the old FCA is not failed and operating the same as the new FCA: It has the same continuity checks as the new FCA (4.1 Ohm +/- .1 Ohm and no grounds), vibrates/buzzes consistently the same as the new FCA, and while in hand I could see movement of the internal shaft/what I believe could be a valve seat moving. (I believe it is operating, the buzzing/valve seat moving as observed from the end looking down the center hole, that is observing silver metal coming into view or valve cylinder moving closer when buzzing, then darkness when not buzzing or the valve cylinder moving out of view or further away). I found an excellent article on modifying an FCA but more importantly helps to understand its directional operation: http://relentlessdiesel.com/forum/viewtopic.php?t=5. Based on this article (great pictures), the FCA is in the full open position at rest., i.e., the largest part of the triangle opening on the valve cylinder is aligned with the inlet holes on the FCA exterior shaft (three holes) and therefore passes maximum fuel thru the valve and out the center hole on the very end, which in-turn sends fuel onto the inlet of the CP3 high pressure side of the pump. This may correlate to the P0088 code when the FCA is unplugged and engine is started, and because the ECM is controlling injectors at idle speed, the rail would be at an elevated pressure above what is needed for idle (i.e., set pressure of approximately 6,000 psi). This is of course the case if no fuel is returned via the COV (because assumed failed) to the fuel tank causing maximum amount of fuel being sent to thru the FCA to the high pressure pump of the CP3. The FCA was observed to vibrate/buzz when the ignition key was in the ACC position, and then there is a delay to ceasing to buzz/vibrate when the ign sw taken to off position for about 5 - 10 seconds delay. The ECM is obviously sending a signal to it by this operation, so the ECM is without any issues from the best of my assessment. Lastly, I confirmed that the truck would crank/start/run (at idle, approximately 700 rpm) with the New FCA disconnected too (this really doesn't add any information since there would not be a difference between the old FCA being installed; there is no electrical communication to the FCA affecting the start) and of course it also throws the P0088 code (and the expected P0251 code). I however did not remove the new FCA and change it back over to the old FCA in order to continue using it and keep the new one as spare. I see no need to worry further about the FCAs. There is one question to ponder, and it is based on the technical article explaining the FCA is directed by the ECM to full open (full rail pressure setpoint) during startup for up to 30 seconds while being started, however when it is disconnected from the ECM (no power) it must physically be full open from spring pressure. This doesn't explain the buzzing/vibration and how the ECM is maintaining the valve full open? I can't correlate what the buzzing of the solenoid is doing when connected to ECM during ignition sw in the ACC position. Anyone that can make sense of this would help close out this aspect of the FCA operation. Now, that I have continued to study the Fuel flow chart I put together and the fuel technical article, I can not find another failure mode associated with the P0088, high rail pressure code than the COV component that does not throw its own sensor connected code (this is an initial thought that still needs to be verified by going thru the list of all of the ECM codes). However, there is a suspect failure of the CPS that feeds a signal into the ECM (per War Eagle), which is used by ECM to generate the control signal to the FCA as referred to in the above technical article too, as well as from the electrical prints I have reviewed from my CD service manual drawing (it is an input in addition to the several others form the prints of which two inputs could potentially cause full fuel flow to the rail/p0088 code; i.e.,. the rail pressure sensor (ruled out since it was just replace and is not throwing a code which I did get when it failed on me previously; and btw, it did not produce a crank/no start condition), idle throttle position switch, and/or accelerator pedal position sensor). The big challenge to overcome, is why the CPS (which I confirmed on the electrical drawings is the Camshaft Position Sensor (CPS) - and according to War Eagle can cause sudden engine shutdown (but did it throw a code War Eagle???)). With believing there are codes specific to these sensors, the COV is the only sensor that can cause a P0088 code and not a code of its own (thanks to input from Ed 5.9 above) and cause a sudden engine shutdown without throwing a code. So I will test the output of the discharge from the COV to the fuel tank for flow during start up, which I would expect to see none if it is the cause of my engine no start/sudden shutdown condition experience on the highway. If ok, then I will be without any logic for another suspect component downstream of the CP3 output or from these other sensors. PS - War Eagle it would be helpful if you can give me any insight into your CPS failure and whether the shop identified any related codes or did you have a code reader at the time and verified that there were no codes??? This would be very helpful and provide the logic I am looking for to confirm that this is a suspect component failure next. Thanks, and btw I have the new COV and would like to just put it in and get immediate feedback, but will test its output from the current one installed before removing to inspect and replace it out ... in the spirit of being disciplined to following thru with the logical testing that my troubleshooting thoughts and plans are directing ...lol.!

I did a cut and paste (see below) from gmctd that was placed on the Dodge Diesel Cummins Forum (thanks for sharing), which I can not thank him enough as it is an EXCELLENT description/technical discussion of the 3rd Generation Fuel System Operation!!!! I am sure it came from Cummins. This was too good not to share and include for all of us that just got to know what is going on so we can make logical decision with our troubleshooting. Now with the accuracy of this technical documentation, it should speed things up with anybody's future troubleshooting! I took some time to get my thoughts together along with factoring together this technical information and all others inputs, and subsequently created a couple of diagrams and notes for tools. I drew-up a flow diagram of the fuel system discussion that is focused on troubleshooting use, which I will neat'n up and post for ease of troubleshooting the fuel system for others. It is a quick way to take in the entire technical document without spending a lot of time reading and understanding it. The major components that should be checked, along with relationship between electrical and mechanical, as well as where the ECM fits into the picture is easy to see, allowing one to follow the fuel system and make determinations on what may not be working properly. It puts to rest hear-say, and sketchy memories too. This should aide others (myself included) in troubleshooting their fuel issues much quicker than how long it has taken me already. I also took time today to sketch a block diagram of my troubleshooting so far: i.e., condition, problem statement, symptom(s)/action(s), feedback loop, and focus areas. This has helped me re-step thru what has happened, factor in new information, and organize my thoughts allowing me to determine "logically" next steps. It may end up being something helpful to others too? Then finally, I wrote my what/if thoughts for questioning why things happen the way they do/did, and what I need to do for answers, validation, or support/refute to develop additional actions or identify faulty components. I know this sounds like a lot of paper thinking but after reading all the other posts that I could get my hands on, it helps sort thru complexities and entanglement for us folks going thru others experiences and data, then combining with our data and making logic of it all JUST IN ORDER TO identify the faulty component (end goal). This saves money on not purchasing unnecessary parts or labor. So if your wondering where this leave me now ...well, I believe in the last post made - I (you) can now determine it is fairly close to where I need to go for the failure/fix. I still don't believe the FCA is failed, because as Ed 5.9 has offered, and now confirmed with the below technical information. Because the COV provides fuel flow/pressure from the LP side of CP3 pump to: 1.) the FCA that controls the "flow" to the HP side of CP3 pump then on to the rail, 2.) the lubrication flow at low pressure (43 psi), and 3.) the "press/flow" excess (i.e., regulated overflow) back to the fuel tank AND based on my current symptoms (Crank/start/shutdown from ign sw position 1/ACC - additional associated details about the start too, and P0088 code), it can be explained that because the FCA on startup (ECM has (allows) FCA demand "full" flow for startup mode i.e., up to full pressure on the rail (23,206 psi)) is not able to control rail pressure fast enough if the COV valve is not working properly to direct fuel flow down path #3. The FCA eventually is able to respond from the overpressure condition by completely shutting fuel off from the HP side of the pump (as designed/expected operation). If the COV is not relieving press/flow back to the fuel tank there is a pressure run away condition (or significant delay in reducing flow from the HP side of the CP3), hence P0088, high rail pressure condition followed by the FCA shutting off fuel to engine causing shutdown. This makes logical sense, especially when you trace it on my flow diagrahm. Additionally, this may not be the only failure component/mode that could cause high pressure on the rail, but right now it (COV) is the next logical and fuel flow path component (i.e., in sequence from the fuel tank in suspect) to troubleshoot and verify its proper operation/condition (thanks Ed 5.9L). This will be done by finding a way to observe fuel flowing back to the fuel tank from the COV outlet. However, as I stated before, there are some "re-do" actions to be taken. I want to verify the hypothesis by looking again at the old FCA and verifying it is not bad, because this could change things some if it is failed. It should act consistently the same as the new FCA and start the engine from the ign sw position 1 (ACC) if so. After identifying another way to look at the FCAs and ECM, there are a couple more checks to perform: 1.) verify the ECM is sending a test pulse to the FCA with a test light across the connector contacts (this occurs when key is in ACC position), 2.) after removal of new FCA, measure continuity, ground, and visual observation of the static solenoid plunger position and compare it to the old FCA solenoid plunger position, and 3.) feel it operate during starting or with it in-hand while not bolted into CP3. These checks need to be done so I can conclude that the FCAs and ECM are operating properly. Now with plan in hand, time to go implement. Will post results and include the diagrams and notes, if there is a way to post them? Hope this will help others. The following (below) is a cut and paste from gmctd that was placed on the Dodge Diesel Cummins Forum (thanks for sharing), which I can not thank him enough as it is an EXCELLENT description/technical discussion of the 3rd Generation Fuel System Operation!!!! I am sure it came from Cummins. This is information that you must keep in your 5.9L Diesel shop notes! CP3 injection pump system I've edited excerpts from the manual for clarity and scope - read it if you will, ignore it if you must....................... FUEL SYSTEM A Robert Bosch high-pressure fuel injection pump is used. The pump is attached to the back of the timing gear housing at the left /front side of the engine DESCRIPTION The fuel system on the 5.9L Common Rail Diesel Engine uses a rotary mechanical fuel injection pump and an Electronic Control Module (ECM) and is a drive-by-wire system, meaning there is no physical throttle cable. The fuel delivery system consists of the: - Accelerator pedal position-sensor module - Air cleaner housing\element - Fuel filter\water separator - Fuel temperature sensor - Fuel heater - Fuel rail pressure relief valve - Fuel rail pressure sensor - Fuel injection pump - Fuel injectors - Fuel tank - Fuel tank filler\vent tube assembly - Fuel tank filler-tube cap - Fuel tank module containing the electric lift pump, roll-over valve and a fuel gauge sending unit (fuel level sensor). - Fuel tubing\lines\hoses - High-pressure fuel injector lines - Low-pressure fuel supply and return lines - Low-pressure fuel return line - Overflow valve - Quantity control Fuel Control Actuator valve - Quick-connect fittings - Water sensor\drain module FUEL INJECTION PUMP The Cummins 5.9L CRD uses the Bosch CP3 injection pump, used also on the DMax 6.6L V8 CRD and the Jeep 2.8L CRD DESCRIPTION A radial, 3-piston pump, with a gearotor pump attached to the back, is used as the high-pressure pump for common-rail fuel pressure generation - in this system it is capable of pressures between 300-1600 bar (4351-23206 psi) . A spring-loaded Cascade Overflow Valve regulates internal housing pressure Regulated internal housing pressure is oem-specific The pump shaft is driven by the timing belt at 1:1 ratio to the crankshaft. Fuel pressure is generated independently of the injection process. A Fuel Control Actuator solenoid valve regulates injection pressure The pump is lubricated by the pumped Diesel fuel and is not responsible for fuel injection timing. OPERATION GEAROTOR PUMP DESCRIPTION The gearotor pump has two functions - draws fuel from the fuel supply - increases fuel pressure for regulation to housing pressure required for internal lubrication and supplying the high-pressure injection pump OPERATION This fuel system uses a gearotor supply-pump attached to the rear of the high-pressure pump. This medium-pressure fuel pump is driven by the end of the high-pressure pump shaft, and can generate 20" vacuum at the fuel inlet at high rpm. The gearotor pump is supplied fuel from the lift pump in the fuel tank through the fuel manager\filter. The outlet of the gearotor pump provides pressurized fuel to a branched circuit internal to the high-pressure pump flange, which supplies both the Fuel Control Actuator solenoid valve and the Cascade Overflow Valve\regulator. Because the gearotor pump increases fuel flow and pressure as engine rpm increases, the pressure and flow is regulated by the COV. The COV and gearotor supply-pump are not serviced independently of the high-pressure pump. CASCADE OVERFLOW VALVE DESCRIPTION The COV is located on the front cover of the high pressure pump. The Cascade Overflow Valve has three functions: - regulation of lubrication fuel to the internal moving parts of the high-pressure pump - regulation of the fuel pressure being supplied to the Fuel Control Actuator solenoid valve - return excess fuel to the fuel tank This regulated internal pressure, known as housing pressure, is determined by engine displacement and power requirements - the 5.9L CRD requires 5-12.4 bar (80-180 psi) For comparison, the 2.8L 4-cyl Jeep CRD requires 5bar maximum (73psi) OPERATION The COV has a spring-loaded center spool-piece that has a drilled channel with three passages: one for initial low-pressure lubrication, one for lubrication at housing-pressure , and one for overflow. The valve is operated in three stages based on the level of pressure at the inlet. Stage 1 When the fuel pressure entering the tip of the COV is between 0 and 3 bar (43psi), pressure is too low to overcome regulator spring tension and fuel flows through the center channel, only . This passage always allows fuel flow through to the pump center-ring and lubricates the pump bearings and internal moving parts. This circuit also allows air to bleed during initial cranking and returns the air to the fuel tank. The COV is in Stage 1 during cranking, only. Stage 2 When the fuel entering the COV exceeds 5bar (73psi), but is less than 12.4bar (180psi), the spool-piece moves against spring tension aligning a second passage for lubrication purposes. Stage 2 can be reached during cranking and initial start up. Stage 3 When fuel pressure exceeds 12.4bar (180psi), the spool-piece aligns with the overflow passage. This stage relieves the pressure into an overflow circuit that sends the fuel back to the inlet side of the gearotor pump, thus limiting maximum fuel pressure to 12.4bar (180psi). Lubrication fuel continues to flow through all channeled passages during this stage. Excess fuel is sent back to the fuel tank through the fuel-return circuit Stage 3 is reached at over-pressure FUEL CONTROL ACTUATOR DESCRIPTION The Fuel Control Actuator solenoid valve is located on the back of the front cover of the high-pressure pump. The solenoid is pulse-width modulated by the ECM and meters the amount of fuel that flows into the high-pressure elements inside the high-pressure pump. The solenoid is inactive up to 30 seconds after IGNition switch is initially keyed to ON position to allow maximum fuel pressure to the fuel rail during cranking and start up. ECM assumes FCA valve control when CPS signal and rail pressure are within acceptable limits OPERATION The Fuel Control Actuator solenoid valve is a pulse-width modulated valve that controls the amount of fuel sent or delayed to the high-pressure pump elements inside the high-pressure pump. The ECM determines the fuel pressure set point based on engine sensor and rail-pressure inputs. If the actual fuel-rail pressure is too low, the ECM commands the solenoid to allow more fuel to flow to the high-pressure pump. This minimizes the difference between the actual fuel-rail pressure reading and the set point. The ECM will also operate the solenoid to delay fuel, reducing flow-rate, if the fuel-rail pressure becomes too high. The FCA valve is commanded open by the ECM to allow the high-pressure pump to build maximum pressure (1600bar, 23,206psi), or closed to reduce rail pressure. Thus, rail fuel-pressure can be increased or decreased independent of engine speed High Pressure Pumping Plungers The FQS valve supplies three high pressure pumping chambers. The pumping chambers have one-way inlet valves that allow fuel to flow into the chambers. The valves then close as the fuel is compressed, causing the high pressure fuel to overcome a spring-loaded ball-and-seat outlet valve. All three pumping chambers are tied together in one circuit internal to the pump and provide high pressure fuel between 300bar (4351psi) and 1600bar (23,206psi) through a steel line to the fuel rail. The pump is driven at 1:1 engine speed and is not responsible for injection timing. Pump function is to provide fuel at high-pressure, while the ECM controls injection pressure and timing. FUEL RAIL DESCRIPTION The fuel rail is mounted to the cylinder-head cover\intake manifold. The rail distributes regulated high-pressure fuel equally to the fuel injectors. A pressure sensor is screwed into the rail so ECM can read and regulate system pressure. A pressure valve is screwed into the fuel rail to allow regulated overflow return to the fuel tank. OPERATION The fuel rail stores the fuel for the injectors at high pressure. At the same time, the pressure oscillations which are generated due to the high-pressure pump delivery and the injection of fuel are dampened by rail volume. The fuel rail is common to all cylinders, hence it’s name "common rail". Even when large quantities of fuel are extracted, the fuel rail maintains a constant inner pressure. This ensures that injection pressure remains constant from the instant the injector opens to the end of the injection event. PRESSURE LIMITING VALVE DESCRIPTION The fuel pressure limiting valve is located on the top of the fuel rail. OPERATION Fuel pressure at the fuel rail is monitored by the fuel rail pressure sensor. If fuel pressure becomes excessive, the high pressure fuel overcomes a spring-loaded plunger with tapered-seat outlet valve, causing the pressure limiting valve to open and vent excess pressure into the fuel drain circuit, and back to the fuel tank. FUEL LINES DESCRIPTION LOW-PRESSURE FUEL LINES All fuel lines up to the fuel injection pump are considered low-pressure. This includes the fuel lines from the fuel tank module to the inlet of the high-pressure fuel injection pump. The fuel-return lines and the fuel-drain lines are also considered low-pressure lines. High-pressure lines are used between the fuel injection pump and the fuel injectors HIGH PRESSURE FUEL LINES High-pressure fuel lines are used between the high pressure fuel injection pump and the fuel rail, and between the fuel rail and fuel injectors All other fuel lines are considered low-pressure lines. OPERATION - HIGH PRESSURE FUEL LINES High-pressure fuel lines deliver fuel under extremely high pressure - between 300-1600 bar (4351-23206 psi) - from the high-pressure pump to the rail to the fuel injectors. The lines expand and contract from the high-pressure fuel pulses generated during the injection process, which can delay the injection event - ECM compensates for that based on component specs All high-pressure fuel lines between the rail and the injectors are of the same length and inside diameter to ensure equal-duration injection events, cylinder to cylinder. Correct high-pressure fuel line usage and installation is critical to smooth engine operation. FUEL MANAGER\FILTER FUEL FILTER / WATER SEPARATOR DESCRIPTION The fuel filter/water separator assembly is located on left side of engine above the starter motor. The assembly also includes the fuel heater, Water-In-Fuel (WIF) sensor and a screened banjo bolt attached at the bottom of the fuel filter canister. OPERATION The fuel filter/water separator protects the fuel injection pump by removing water and contaminants from the fuel. The construction of the filter/separator allows fuel to pass through it, but helps prevent moisture (water) from doing so. Moisture precipitates out and collects at the bottom of the canister. A screened banjo-bolt is attached to the filtered outlet at the bottom of the fuel filter canister to provide additional filtering for the high pressure fuel system components. A Water-In-Fuel (WIF) sensor is attached to the lower side of fuel filter housing. A fuel heater is installed into the top of the filter/separator housing. WATER IN FUEL SENSOR DESCRIPTION The Water-In-Fuel (WIF) sensor is located on the side of the fuel filter/water separator canister. OPERATION The sensor varies an input to the Engine Control Module (ECM) when it senses water in the fuel filter/water separator. As the water level in the filter/separator increases, the resistance across the WIF sensor decreases. This decrease in resistance is sent as a signal to the ECM and compared to a standard reference value. Once the value drops to 30 to 40 kilohms, the ECM will activate the water-in-fuel warning lamp through CCD bus circuits. This all takes place when the ignition key is initially put in the ON position. The ECM continues to monitor the input while the engine is running. FUEL HEATER DESCRIPTION The fuel heater assembly is located on the side of the fuel filter housing and internal to the fuel filter housing . The heater/element assembly is equipped with a temperature sensor (thermostat) that senses fuel temperature. This sensor is attached to the fuel heater/element assembly. OPERATION The fuel heater is used to prevent diesel fuel from waxing during cold weather operation. When the fuel temperature is below 45° ±8 F (7°C), the temperature sensor allows current to flow to the heater element warming the fuel. When the fuel temperature is above 75° ±8 F (24°C), the sensor stops current flow to the heater element. Battery voltage to operate the fuel heater element is supplied from the ignition switch and through a solid state device in the IPM. There is no Fuel Heater Relay - fuel heater element and solid-state device in IPM are not ECM controlled. The heater element operates on 12 volts, 300 watts at 0° F (-18° C). The fuel heater is used to prevent diesel fuel from waxing during cold weather operation. A malfunctioning fuel heater can cause a wax build-up in the fuel filter/water separator. Wax build-up in the filter/ separator can cause engine starting problems and prevent the engine from revving up. It can also cause blue or white fog-like exhaust. If the heater is not operating in cold temperatures, the engine may not operate due to fuel waxing. The fuel heater assembly is located on the side of fuel filter housing and internal to the fuel filter housing. The heater assembly is equipped with a built-in fuel temperature sensor (thermostat) that senses fuel temperature. When fuel temperature drops below 45° ± 8° F (7° C), the sensor allows current to flow to built-in heater element to warm fuel. When fuel temperature rises above 75 °± 8° F (24° C), the sensor stops current flow to heater element (circuit is open). Voltage to operate fuel heater element is supplied from ignition switch, through the solid-state device in IPM, to fuel temperature sensor and on to fuel heater element. The heater element operates on 12 volts, 300 watts at 0 °F (-18° C). As temperature increases, power requirements decrease. A minimum of 7 volts is required to operate the fuel heater. The resistance value of the heater element is less than 1 ohm (cold) and up to 1000 ohms warm FUEL TRANSFER PUMP ELECTRIC FUEL LIFT PUMP '03-'04 trucks have a Carter sliding-vane type lift pump attached to the fuel manager head on the engine, supplying ~15psi pressure, internally bypassed, with an internal pre-filter screen '05^ trucks have a rotary-vane type lift pump in the fuel module in the tank, supplying ~ 9psi, externally bypassed, returning excess fuel to the tank, with a pre-filter screen DESCRIPTION The '05^ fuel transfer pump (fuel lift pump) is part of the fuel pump module . The fuel pump module is located in the fuel tank. The 12–volt electric pump is operated and controlled by the Engine Control Module (ECM). The ECM controls a relay in the Intelligent Power Module (IPM) for transfer pump operation. OPERATION The purpose of the fuel transfer pump is to supply (transfer) a low-pressure fuel source from the fuel tank through the fuel filter/water separator to the high-pressure fuel injection pump. Check valves within the pump control direction of fuel flow and prevent fuel bleed-back during engine shut down. Operating pressure is 9psi @ 50gph, maximum current flow to the pump is 5 amperes @100 percent duty-cycle.. The transfer pump is self-priming: when the key is first turned on (without cranking engine), the pump will operate for approximately 2 seconds and then shut off (Note: When ambient temperatures are cold enough to cause the intake air heaters to operate, the fuel lift pump will operate during the entire intake air pre-heat cycle). The pump will also operate for up to 25 seconds after the starter is engaged, and then stop if the engine is not running. A safety feature ensures the pump will shut off immediately if the key is on and the engine stops running. The fuel volume of the transfer pump will always provide more fuel than the fuel injection pump requires. Excess fuel is returned from the injection pump through the COV overflow valve back to the fuel tank. The oem lift pump is of the flow-thru-when-failed type - the internal gearotor lift pump in the CP3 will pump 20" vacuum, and is designed to pull fuel from the tank thru a filter head - if the replacement aftermarket remote lift pump is not flow-thru, the engine will stop when the lift pump fails. Always be sure the replacement LP is flow-thru type

Current Analysis: Excellent input Edwin, I really appreciate the thought here with the delta time to pressurize logic. Btw, the ignition switch 1st position more correctly as you state is the accessories (ACC) position, and the second position is Run, and the next position is Start. I was not sure since they are not labeled and my thoughts were too far ahead with my focus on adding all this troublshooting activity up. I also may have overstated how long it runs after starting because it is more in order of 5 seconds, tops. However, the engine sounds very normal after starting - just about stabilizing at an idle condition, and then as one would think everything is good, it slowly dies to off with no discernable parting good-bye. The starting, running, and shutdown as I explain it are "exactly" consistent in behavior each and every time. Not knowing yet (unverified) if there is actual high pressure condition (which I do believe is occurring "now" as was not "before" with the old FCA installed), your thought sounds logical from what I understand about the fuel system (quick course I found and viewed on the Cummings U-Tube videos about the 2003 5.9L diesel design/operation - very informative for us novice diesel owner/mechanics). I can't quite grasp why it starts however with this new FCA and not the old FCA (btw i shook the old FCA as I sit here and write this blog, and I do hear a very light rattle sound, but can't remember about the new one ...if this means anything?). My initial thoughts are that the old FCA may "not" be bad (i.e., I did not check whether the truck will start from the ignition switch 1st position (ACC) or not when the old FCA was installed?). My conclusion about why I thought that the origninal FCA was potentially bad was due to when I disconnected it electrically and the truck started right up - but had very noticeable white smoky exhaust and I immediately shut the truck off as to not run it with no ECM signal to the FCA, believing it to be the smoking gun. I sort of learned about this ignition switch start characteristic as I was thoroughly testing/cycling the new FCA and batteries ( when i got the no start response) and also, since when changing out the FCA I heard a venting noise, which caused me concern that air was going into the system since I did not see any substanative leakage of fuel from the CP3 and I wanted to rule out air in the fuel flow to the injectors. I did cycle the ignition switch several long times to vent the system before trying the first crank to start. Being the theory is a wag, it will stay as a hypothesis for now. Angus, I will continue to post my troubleshooting efforts until the root cause is found and differentiated from the necessary learning or trial by error steps being taken, and documented for all others to use. I too am frustrated more from the "large majority" if not closer to "all" the other posts I have read very rarely come to conclusion/closure for their cause or ultimate fix!!! Not to say there aren't a "few" (mainly the ones that find the fix step one, not the ones who spend multiple troubleshooting steps with highly engaged troubleshooting thoughts), for those others that are reading and not to be offended. Operating experience should be shared to save and benefit others regardless of the pain it produces for us lucky ones. It is not much help if conclusions reached are not shared. Anyhow, two cents worth and my plan is to put my money where my mouth is so I can criticize and not be guilty. No actually, knowing how painful troubleshooting can be, "all" those others at least get credit for starting their communications but by the time they finally arrived at their conclusions, they more than deserved an end to their misery and to take it to the grave. Revised Troubleshooting Plan: Ok, the new theory (offered above) and the associated suspect cause: failed COV (which at this point I am not fully versed on this component/function yet - must do some research and develop my plan to test it). However first, since there is unfinished business ruling out or understanding the FCA more thoroughly, I should remove the new FCA, re-install the old FCA, and determine whether I can get the same engine start condition from ignition switch 1st position (ACC). I will also conduct the so called rattle test and take continuity readings on the electrical side on the new FCA ( which btw the old FCA terminal readings were approximately 2.4 - 3.0 ohms and no grounds) in order to have the data if nothing else. This will hopefully rule out or confirm the FCA failure. Then if it is failed low (i.e, no fuel being demanded from the CP3), this would indicate there is another issue in the fuel system (i.e., two failures), in order to be consistent with the new FCA (considering it is good) over pressurizing the rail. If it is not failed, then if both FCAs are good there should be consistent start characteristics (i.e., starting, and continuity checks), There is one condition that may be a cause however, that both FCAs are failed high, but this should be highly unlikely ( and may end up only being ruled out by finding what is causing the overpressure condition). I have to think more about and factor in why no overpressure code (P0088) was received the night of the sudden engine shutdown but yet now with the new FCA and/or with this ignition switch start characteristic it is consistently is setting the code? From what I can determine with internet fourm research/reading and the help of this site: the suspect cause areas are: COV (CP3 internal pressure regulator) or a fuel return line that is not routing excessive fuel back to the gas tank (there are several of which I must determine which ones will cause a rail over pressure condition) if the FCA is operating correctly. I will hold off with further checks of the fuel system until this FCA plan leg is completed, data obtained, and more analysis conducted. More to come. Thanks, and all input is welcome, much less needed!

Replaced the FCA tonight and interesting enough truck now starts, then shuts-down within 15 - 20 seconds. the start reaches between 600 - 700 rpm then slowly dies/stops running. It now throws the code P0088 (i.e., Fuel Rail/System Pressure - Too High code) consistently (after clearing codes several times). Not sure what to make of this so I must study some more and determine where to go with troubleshooting. One peculure aspect is that it only starts from the first key on position and it will not start when turning it from the second key position (ignition lights on) - not sure what is the reason for this either? Initial thoughts now are to follow-through with fuel system checks down stream of filter housing unless I learn more about the P0088 code. The COV and Cam Position sensor haven't been forgotten. Any additional thoughts are welcome.

Ok, All (including Edwin ...and btw thank you for your reply which makes sense to me!), After spending most of Sunday afternoon replacing the batteries, painstakingly cleaning/replacing all leads and terminal connections, lifting grounds and doing the same, carefully inspecting cables/wires and wire tying them neatly (to aircraft standards), then after performing continuity and voltage checks for electrical connections, I put system on charge, and instead of trying to crank engine, decided best to drink a beer and pondering how to go forward if the battery, ground, voltage to ECM is not the problem. i needed to relax and rethink everything so far with all you inputs, internet troubleshooting data, and getting rest for work week ahead. This evening after returning from office, I checked the charging of new batteries and system voltage as indicated on instrument panel (reading obtained was 13.8-9 volts give or take +/-.1 vdc), then tried to crank engine with a resulting no start. Being that the electrical system is now off the list and not being dressed for dirty work, I decided best effort would be (before I read Edwin's post) to disconnect the fca and try to re-crank. Well, it started right up with a touch of starter!?? I had read in somebody's diesel post that a way to check the afca, was to unplug it, and try to crank engine, and if it started up then shutout down and replace. I did so and also observed heavy white smoke from exhaust . Now I happen to have an fca part on the shelf from my earlier troubleshooting efforts of the surging/no power condition associated with the failure of the fuel rail pressure sensor. I will change it, and confirm its the root cause of the sudden engine shutdown with no warning/indications/other symptoms (other than crank/no start) during the labor day return trip home highway driving the shutdown was experienced. This being where the troubleshooting sits to-date (i.e., appears to be good news for failure mechanism), I will comment further that there was no definitive fca failure cause of condition associated with a sudden engine shutdown/stop running failure that anyone has posted nor Mopar documented where this check was warranted as a potential problem for the condition? I still plan to replace alternator when it arrives, and upon verification this is in fact my problem, it gives rise to whether I should stock critical parts (like pressure sensor, fca, fuel filter, etc) in the truck? These part failures are so easy to replace in the field that had I been towed to a mechanic, I am sure the cost of these parts would pale as cheap compared to these bills, and time or part costs to boot! Edwin, I agree with your situation with the fca operation you encountered because I had been under the same impression of its faulty operation. I had initially bought the fca when troubleshooting my surging/no power condition caused by the failure of the fuel rail press sensor following washing the engine compartment this past early summer. I did have the pressure relief valve (cascade overflow valve?) on my list and had it not been for this turn of events would have further pursued the fuel system downstream of the lift/tank pump. I have carefully documented yours and others input, which will go into my manual for the truck because it is only time until it will be needed!!!! Thanks