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With today's electronic lift pumps from FASS and Airdog, TYPICALLY they do not come with a way to easily adjust fuel pressure. There are options out there but they are quite spendy and there's easier ways to accomplish the same thing. So for those who have pumps that do not have an external/adjustable regulator, your pump more than likely uses a spring and ball to regulate fuel pressure. Springs should be provided from the pump manufacturer to provide adequate pressures. Typically between 16-18psi. The pumps use a hard plastic ball, either a Buna or Viton ball. This will create a seal when the pump is off and keep fuel from "leaking" or "moving" in the lines once the pump is off. The springs can be inconsistent which can cause erratic fuel pressure readings or lower then expected readings. Using this diagram of a FASS system, if you remove the hose/fitting that is connected to the "air/vapor return to the tank" you will find a spring a ball, it will look like this. If your spring comes out looking like this... You were more then likely experiencing erratic fuel pressures. You could either straighten out the spring and reinstall or replace the spring all together. I only have experience with FASS but I called FASS support and they sent me a replacement. I imagine the same would happen with Airdog. The next factor in all this are the balls. In my research I've found that FASS uses a Buna ball and Airdog uses a Viton ball. I was having a mixed bag of issues, erratic fuel pressures and also lower then expected fuel pressures. Upon removing the spring and ball I found my spring had twisted (previous pic) and that the ball had indented into the spring. You can see the indentation here. I tried a couple replacement balls from FASS with the same results. I then went with a Viton ball and the problems haven't returned. The Viton ball is stronger material and seems to be holding up well. If you're still having lower pressure issues then you can put a washer in to shim the spring and raise pressure. The following measurements should get you in the ball park but make sure you double check you're not adding any additional restriction by using to small of an ID. Here are the measurements: OD - .631" ID - .320" thickness - .039" ***This washer/shim should be added between the fitting and the spring NOT between the spring and ball.*** So what helped fixed my issues was going with a Viton ball and a 17lb spring. This isn't meant to say one company is better then the other, just what I found out in my research and what fixed my problem. The point of this article is to help educate others on potential fixes. ***Additional notes*** List of parts I used Viton Ball HERE 17lb spring HERE I understand these are labeled as Airdog parts but they worked fine in my FASS 150. The Airdog fitting DID NOT work on my FASS pump so if you're looking to replace that on your FASS 150 you would need to contact FASS to get a replacement. Here's the difference FASS LEFT AIRDOG RIGHT Pretty noticeable difference in threads and overall length so if replacing these fittings they must be brand specific.
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Fuel Pressure Specification For Bosch VP44 Injection Pump
Mopar1973Man posted an Cummins article in Fuel
Fuel Pressure Specification For Bosch VP44 Injection Pumps Here is a copy of the fuel system specifications from the Dodge Factory Service Manual. This is for your Dodge Cummins Turbo diesel truck with a Bosch VP44 injection pump. Fuel pressure Normal fuel pressure should float about 14-15 PSI running down the pavement. It should never fall below 10 PSI at all. Here is a colorize fuel pressure gauge to give you a clue of the fuel pressure span you want. You want the needle to stay in the green at all times. Yellow zone is a warning that you should check the fuel filter, lift pump performance, overflow valve, etc. This is undocumented maximum pressure is 20 PSI. Now take notice to the overflow valve is set for 14 PSI so excessive pumping of fuel does nothing for performance except create more heat in the fuel, which in turns reduces the cooling ability of the fuel and adds more stress to the lift pump. So a little extra fuel pressure is a good thing because it ensures the Bosch VP44 injection pump stays cooled and lubricated properly. However, excessive fuel pressure will heat the fuel and reduced the cooling ability of the fuel. Now always remember that the only lubrication the Bosch VP44 injection pump will see is the fuel itself so if you don't have enough fuel pressure it will cause damage to the Bosch VP44 injection pump. It's like the same as running the engine with low oil pressure it will continue to run, but the damage to the engine will occur. On the other hand, the Bosch VP44 injection pumps, which happen to be about $1,200 to replace. Pressure Drop The amount of fuel pressure drop between idle and wide-open throttle. 2-3 PSI drop from idle to WOT is normal. However, 5 PSI or more pressure drop from idle to WOT is pointing out a failed lift pump, plugged filter, and/or plumbing restrictions. 2-3 PSI Is Normal Dropping more than 5 PSI is pointing towards a failed lift pump, plugged filter, or restrictive plumbing. Just to show you the difference in the stock plumbing which is 6mm ID plumbing and most performance pumps come with 1/2" ID plumbing. These pictures will give you an idea... The first picture is a Big Line fitting over the top of the stock plumbing. Then the second picture compares the stock 6mm ID steel lines to a 1/2" ID Big Line hose. The best way to show this example of restrictions is to let's say your house is on fire. You know your garden hose has 80 PSI of pressure, but the garden hose is only 5/8" ID hose. Your wife calls 911 and gets the fire department coming in the meantime you keep fighting the fire with your little 5/8" garden hose and losing the battle. The fire department shows up and pulls a 2 1/2" hose off the truck and charges it at 80 PSI and now winning the battle. Your fire is put out! What is so different? No matter what the size of the fuel line will dictate how much volume can be pushed through the fuel line. Like the story above the water pressure was the same at 80 PSI, but the hose size jumped from 5/8" to 2 1/2" ID hose and the volume changes are the size of hose. So the same thing applies to the stock fuel system. The stock banjo bolts and 6mm ID pipes are just too restrictive and cannot supply enough volume of fuel for that Bosch VP44 injection pump demands. This why I highly suggest you go up to 1/2" ID plumbing. Reasons Why Fuel Pressure Is Critical Let's take a look at a Bosch VP44 injection pump. I've labeled the fuel lines supplying fuel and return line plus the overflow valve. Now I know there is a ton of rumors on the internet of all kinds of minimum pressures for a Bosch VP44 injection pump. I'm going to say stick with the Dodge Factory Service Manual Specifications for fuel pressure. Now let's talk a bit more about the flow of the fuel. The lift pump supplies pressurized fuel to the Bosch VP44 injection pump the overflow valve regulates how much fuel pressure is held. Excessive fuel pressure is returned to the fuel tank. The picture below is of the bleed hole in the overflow valve this image was magnified x10 to show you how small the bleed hole really is. Give you an idea the size of the hole use a single strand of 14 AWG copper wire, and it will NOT fit the hole. The bleed hole is there solely for bleeding air out of the system which air will pass through this tiny hole rather easy but fuel will not. However, if you're looking for long life from a Bosch VP44 injection pump, I would personally suggest you adjust your minimum pressure to 14 PSI this will ensure the overflow valve remain open and a constant fuel flow through the Bosch VP44 injection pump and keep it cool all the time. Let me play out a simple scenario. Let's say my fuel pressure is roughly 10-11 PSI. I'm going to drive up into the back country approximately 40 miles with my Dodge Cummins towing an 8x8 utility trailer. Now the whole trip heading uphill into the mountain towing an empty trailer is going to be enough fuel flowing to the injectors to keep the Bosch VP44 injection pump happy. However, I've spent the day and loaded up with firewood and now coming back down the mountain loaded. I'm using my exhaust brake and coasting most of the way down taking it slow and easy. At this point, the injectors are no longer firing so the Bosch VP44 injection pump is not pumping fuel out to the injectors. Furthermore, the overflow valve closes at about 10-11 PSI so let's say it did close. Now where is the fuel going??? Nowhere! It is pooled up in the injection pump and gaining heat and being broke down. You've also removed the cooling and lubricating of the Bosch VP44 injection pump so now it actually taking on damage. To give you a feel for the fuel flow coming from the injection pump with an AirDog 150 at 17.5 PSI of fuel pressure, I've got a video to explain that quickly. I've heard rumors of some people trying to develop a cool down system for the Bosch VP44 Injection pump but after making the video above, there is just no way to cool down the injection pump using the lift pump of even the AirDog/FASS series. The whole problem is the restrictions inside the Bosch VP44 injection pump and the overflow valve as seen in the video above. So the only way to keep the Bosch VP44 injection pump cool is to keep fuel flowing through it at all times. So to keep the overflow valve open I suggest the 14 PSI minimum pressure. I'm currently at 136K miles on my Bosch VP44 injection pump and still going strong using a 16 PSI minimum pressure and an 18 PSI idle pressure. Here is a short video of stable fuel pressure from 55 MPH to 70 MPH at WOT. Here is another video done with idling, cruising, and WOT operation. Yes. I got a bit carried away and sloshed the fuel in the tank and sucked an air bubble and the pressure fell off. Cranking Pressure Test Here is a simple test on how to do the test for cranking fuel pressure. Pull the fuel pump relay in the PDC and then attempt to start the engine. Pay attention to the fuel pressure gauge during cranking. Be aware this test will trip a P1689 code and light the CHECK ENGINE light. Excessive cranking pressure can lead to difficult starting problems. Suggested Lift Pump Replacement You should replace the stock fuel system completely since it cannot supply enough fuel for even stock requirements without causing damage to the Bosch VP44 injection pump or adding stress to the lift pump. The pumps I suggest are proven and come with a lifetime warranty. These pumps come with a full kit and replace everything from the fuel tank to Bosch VP44 injection pump. AirDog 100, 150, or 165 Raptor 100 or 150 FASS 100 or 150 FASS DDRP (DDRP Ver.2 - 89 GPH) I don't suggest these pumps... Because they don't address the pump location, plumbing restrictions, or come with much of warranty. Stock Carter or Carter Campaign Pump (4090046) Holley Blue or Holley Black FASS DDRP (DDRP Ver.1 - 40 GPH) AirTex Mopar's Notes: That was true for the DDRP Ver.1 However, DDRP-02 is rated at 89 GPH and will hold pressure. It is listed as a Stock replacement pump designed to perform better than the Stock pump, but not for Chips that add fueling. I place a Power Puck on my truck with the DDRP-02 and saw no difference in FP at either idle or WOT, (PP is a timing chip doesn't change the amount of fuel). That said the PP is currently removed from my truck as I overpowered my clutch both loaded and unloaded, back to the stock clutch is fine. Looking for a Valair possible DD organic, or SD Kevlar/Ceramic. It is currently in the stock location and giving 15 psi at idle and 10 at WOT. Information Provided By: rhagfo http://www.cumminsforum.com/forum/98-5-02-powertrain/404412-fass-ddrp-02-a.html#post4197714 Additional Information (About Performance Crowds & Fuel Pressure) I've seen several times where people will link back to performance pump builders and quoting where they say, "(Un-named) proved that 5 PSI, under load, made all the horsepower the VP44 pump could make, even with stock fuel lines, fittings and supply pump." This might be true but there is nothing ever said about the life span of the pump at these conditions. So... Please do not follow these performance crowds into destroying a perfectly good Bosch VP44 injection pump. The fact still remains from Bosch the actual designer of the Bosch VP44 injection pump states that injection pump should return 70% of the fuel back to the fuel tank for cooling and lubrication purpose of the VP44. Being the only way a Bosch VP44 injection pump can do this is to have fuel pressure above 14 PSI to open the overflow valve. Then if the stock Bosch VP44 injection pump with an enhancement box say an Edge Comp on 5x5 can consume 15-20 GPH that means the stock 35 GPH pump cannot keep up with Bosch's design of 70% return volume. So this why products like AirDog, Raptor and FASS was created because they actually meet the demands of the Bosch VP44 injection pump. Then another fact that Bosch will let you know of is that diaphragm damage occurs from operating the Bosch VP44 injection pump at low fuel pressures. Making matters worse is that no Bosch injection re-builder will void warranty a VP44 injection pump with diaphragm damage. Dead give away that you had a bad lift pump or low fuel pressure problems. Please view the Bosch VP44 exploded view page to see there is no diaphragm in the Revision 027 Bosch VP44 Injection Pump Then the other fact is right from the Dodge Factory Service Manual has the minimum fuel pressures (picture at the top of the page). It even states the pressure that the overflow valve requires to open. Refer to the Overflow Valve Testing from the Dodge Factory Service Manual and see that the overflow valve should remain closed at 10 PSI and open by 14 PSI. So if the overflow valve is close by 10 PSI, then you extra cooling and lubrication just disappeared. So ultimately it suggested having a fuel system of no less than 100 GPH supply that can maintain a minimum pressure of 14-15 PSI at WOT. This will great extend the life of the VP44 because it keeps the electronics cooler longer and keeps the rotating parts lubricated properly. So please people let the facts and information from the actual designers of the injection pump (Bosch) and engine (Cummins) provide you proper information for your fuel system for your engine. Don't be swayed by performance shops claim of high horse output with little fuel pressure. As I proved right here doesn't work for the longevity of the VP44 injection pump... Another thing to bring up there are people that are increasing fuel pressures above 20 PSI. Please don't do this. The return port leaving the VP44 pump isn't very big at all. The return port is on the left and supply is on the right. As you can see increasing fuel pressures above 20 PSI put you at risk for shaft seal failure. Increasing the pressure above 20 PSI isn't going to improve the return flow. I say stick with the 14-20 PSI pressure range for seal safety. Additional Information (About Maximum Flow Rates) Here are some calculated flow abilities of the stock fuel system vs. 1/2" big line kits. This is not calculating bend, turns, offices just straight flow for open end plumbing and this is a rough calculation. Pipe Size Gallon Per Hour Flow Rate Gallon Per Minute Flow Rate 6mm ID pipe 75 GPH @ 15 PSI 1.2 GPM @ 15 PSI 1/2" ID pipe 570 GPH @ 15 PSI 9.5 GPM @ 15 PSI Use The banjo bolt Shrader valve to test for fuel pressure, Item 3 in the above diagram. If you have a 98-99 truck the port might be on top of the fuel filter housing. You can see the 90* bend fitting coming out of the top of the fuel filter housing in the below picture. Install a Shrader valve and test from there. I'm hearing of tales of shops, mechanics, or dealers doing the old hook up the fuel pressure gauge and only checking fuel pressure at idle. This is wrong. Because I've seen lots of cases where fuel line restriction, fuel filter plugging, gelling fuel and other thing causing fuel pressure to drop out under load. Like this video from a friend of mine, you'll see he's got awesome fuel pressure at an idle (where most shops gave him the green light). However, what the shops did not test for is WOT at highway speed, and you'll see in the video, he can pull way down to 0 PSI. Anything under 14 PSI is a concern... Anything under 10 PSI is a serious problem. As for having a gauge in the cab all Dodge Cummins trucks should have a fuel pressure gauge in the cab. Because like you seen bench testing with an idle pressure is meaningless if you can't see the WOT pressure at highway speed.- 3 reviews
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Fuel Pressure Specification For Bosch VP44 Injection Pumps Here is a copy of the fuel system specifications from the Dodge Factory Service Manual. This is for your Dodge Cummins Turbo diesel truck with a Bosch VP44 injection pump. Fuel pressure Normal fuel pressure should float about 14-15 PSI running down the pavement. It should never fall below 10 PSI at all. Here is a colorize fuel pressure gauge to give you a clue of the fuel pressure span you want. You want the needle to stay in the green at all times. Yellow zone is a warning that you should check the fuel filter, lift pump performance, overflow valve, etc. This is undocumented maximum pressure is 20 PSI. Now take notice to the overflow valve is set for 14 PSI so excessive pumping of fuel does nothing for performance except create more heat in the fuel, which in turns reduces the cooling ability of the fuel and adds more stress to the lift pump. So a little extra fuel pressure is a good thing because it ensures the Bosch VP44 injection pump stays cooled and lubricated properly. However, excessive fuel pressure will heat the fuel and reduced the cooling ability of the fuel. Now always remember that the only lubrication the Bosch VP44 injection pump will see is the fuel itself so if you don't have enough fuel pressure it will cause damage to the Bosch VP44 injection pump. It's like the same as running the engine with low oil pressure it will continue to run, but the damage to the engine will occur. On the other hand, the Bosch VP44 injection pumps, which happen to be about $1,200 to replace. Pressure Drop The amount of fuel pressure drop between idle and wide-open throttle. 2-3 PSI drop from idle to WOT is normal. However, 5 PSI or more pressure drop from idle to WOT is pointing out a failed lift pump, plugged filter, and/or plumbing restrictions. 2-3 PSI Is Normal Dropping more than 5 PSI is pointing towards a failed lift pump, plugged filter, or restrictive plumbing. Just to show you the difference in the stock plumbing which is 6mm ID plumbing and most performance pumps come with 1/2" ID plumbing. These pictures will give you an idea... The first picture is a Big Line fitting over the top of the stock plumbing. Then the second picture compares the stock 6mm ID steel lines to a 1/2" ID Big Line hose. The best way to show this example of restrictions is to let's say your house is on fire. You know your garden hose has 80 PSI of pressure, but the garden hose is only 5/8" ID hose. Your wife calls 911 and gets the fire department coming in the meantime you keep fighting the fire with your little 5/8" garden hose and losing the battle. The fire department shows up and pulls a 2 1/2" hose off the truck and charges it at 80 PSI and now winning the battle. Your fire is put out! What is so different? No matter what the size of the fuel line will dictate how much volume can be pushed through the fuel line. Like the story above the water pressure was the same at 80 PSI, but the hose size jumped from 5/8" to 2 1/2" ID hose and the volume changes are the size of hose. So the same thing applies to the stock fuel system. The stock banjo bolts and 6mm ID pipes are just too restrictive and cannot supply enough volume of fuel for that Bosch VP44 injection pump demands. This why I highly suggest you go up to 1/2" ID plumbing. Reasons Why Fuel Pressure Is Critical Let's take a look at a Bosch VP44 injection pump. I've labeled the fuel lines supplying fuel and return line plus the overflow valve. Now I know there is a ton of rumors on the internet of all kinds of minimum pressures for a Bosch VP44 injection pump. I'm going to say stick with the Dodge Factory Service Manual Specifications for fuel pressure. Now let's talk a bit more about the flow of the fuel. The lift pump supplies pressurized fuel to the Bosch VP44 injection pump the overflow valve regulates how much fuel pressure is held. Excessive fuel pressure is returned to the fuel tank. The picture below is of the bleed hole in the overflow valve this image was magnified x10 to show you how small the bleed hole really is. Give you an idea the size of the hole use a single strand of 14 AWG copper wire, and it will NOT fit the hole. The bleed hole is there solely for bleeding air out of the system which air will pass through this tiny hole rather easy but fuel will not. However, if you're looking for long life from a Bosch VP44 injection pump, I would personally suggest you adjust your minimum pressure to 14 PSI this will ensure the overflow valve remain open and a constant fuel flow through the Bosch VP44 injection pump and keep it cool all the time. Let me play out a simple scenario. Let's say my fuel pressure is roughly 10-11 PSI. I'm going to drive up into the back country approximately 40 miles with my Dodge Cummins towing an 8x8 utility trailer. Now the whole trip heading uphill into the mountain towing an empty trailer is going to be enough fuel flowing to the injectors to keep the Bosch VP44 injection pump happy. However, I've spent the day and loaded up with firewood and now coming back down the mountain loaded. I'm using my exhaust brake and coasting most of the way down taking it slow and easy. At this point, the injectors are no longer firing so the Bosch VP44 injection pump is not pumping fuel out to the injectors. Furthermore, the overflow valve closes at about 10-11 PSI so let's say it did close. Now where is the fuel going??? Nowhere! It is pooled up in the injection pump and gaining heat and being broke down. You've also removed the cooling and lubricating of the Bosch VP44 injection pump so now it actually taking on damage. To give you a feel for the fuel flow coming from the injection pump with an AirDog 150 at 17.5 PSI of fuel pressure, I've got a video to explain that quickly. I've heard rumors of some people trying to develop a cool down system for the Bosch VP44 Injection pump but after making the video above, there is just no way to cool down the injection pump using the lift pump of even the AirDog/FASS series. The whole problem is the restrictions inside the Bosch VP44 injection pump and the overflow valve as seen in the video above. So the only way to keep the Bosch VP44 injection pump cool is to keep fuel flowing through it at all times. So to keep the overflow valve open I suggest the 14 PSI minimum pressure. I'm currently at 136K miles on my Bosch VP44 injection pump and still going strong using a 16 PSI minimum pressure and an 18 PSI idle pressure. Here is a short video of stable fuel pressure from 55 MPH to 70 MPH at WOT. Here is another video done with idling, cruising, and WOT operation. Yes. I got a bit carried away and sloshed the fuel in the tank and sucked an air bubble and the pressure fell off. Cranking Pressure Test Here is a simple test on how to do the test for cranking fuel pressure. Pull the fuel pump relay in the PDC and then attempt to start the engine. Pay attention to the fuel pressure gauge during cranking. Be aware this test will trip a P1689 code and light the CHECK ENGINE light. Excessive cranking pressure can lead to difficult starting problems. Suggested Lift Pump Replacement You should replace the stock fuel system completely since it cannot supply enough fuel for even stock requirements without causing damage to the Bosch VP44 injection pump or adding stress to the lift pump. The pumps I suggest are proven and come with a lifetime warranty. These pumps come with a full kit and replace everything from the fuel tank to Bosch VP44 injection pump. AirDog 100, 150, or 165 Raptor 100 or 150 FASS 100 or 150 FASS DDRP (DDRP Ver.2 - 89 GPH) I don't suggest these pumps... Because they don't address the pump location, plumbing restrictions, or come with much of warranty. Stock Carter or Carter Campaign Pump (4090046) Holley Blue or Holley Black FASS DDRP (DDRP Ver.1 - 40 GPH) AirTex Mopar's Notes: That was true for the DDRP Ver.1 However, DDRP-02 is rated at 89 GPH and will hold pressure. It is listed as a Stock replacement pump designed to perform better than the Stock pump, but not for Chips that add fueling. I place a Power Puck on my truck with the DDRP-02 and saw no difference in FP at either idle or WOT, (PP is a timing chip doesn't change the amount of fuel). That said the PP is currently removed from my truck as I overpowered my clutch both loaded and unloaded, back to the stock clutch is fine. Looking for a Valair possible DD organic, or SD Kevlar/Ceramic. It is currently in the stock location and giving 15 psi at idle and 10 at WOT. Information Provided By: rhagfo http://www.cumminsforum.com/forum/98-5-02-powertrain/404412-fass-ddrp-02-a.html#post4197714 Additional Information (About Performance Crowds & Fuel Pressure) I've seen several times where people will link back to performance pump builders and quoting where they say, "(Un-named) proved that 5 PSI, under load, made all the horsepower the VP44 pump could make, even with stock fuel lines, fittings and supply pump." This might be true but there is nothing ever said about the life span of the pump at these conditions. So... Please do not follow these performance crowds into destroying a perfectly good Bosch VP44 injection pump. The fact still remains from Bosch the actual designer of the Bosch VP44 injection pump states that injection pump should return 70% of the fuel back to the fuel tank for cooling and lubrication purpose of the VP44. Being the only way a Bosch VP44 injection pump can do this is to have fuel pressure above 14 PSI to open the overflow valve. Then if the stock Bosch VP44 injection pump with an enhancement box say an Edge Comp on 5x5 can consume 15-20 GPH that means the stock 35 GPH pump cannot keep up with Bosch's design of 70% return volume. So this why products like AirDog, Raptor and FASS was created because they actually meet the demands of the Bosch VP44 injection pump. Then another fact that Bosch will let you know of is that diaphragm damage occurs from operating the Bosch VP44 injection pump at low fuel pressures. Making matters worse is that no Bosch injection re-builder will void warranty a VP44 injection pump with diaphragm damage. Dead give away that you had a bad lift pump or low fuel pressure problems. Please view the Bosch VP44 exploded view page to see there is no diaphragm in the Revision 027 Bosch VP44 Injection Pump Then the other fact is right from the Dodge Factory Service Manual has the minimum fuel pressures (picture at the top of the page). It even states the pressure that the overflow valve requires to open. Refer to the Overflow Valve Testing from the Dodge Factory Service Manual and see that the overflow valve should remain closed at 10 PSI and open by 14 PSI. So if the overflow valve is close by 10 PSI, then you extra cooling and lubrication just disappeared. So ultimately it suggested having a fuel system of no less than 100 GPH supply that can maintain a minimum pressure of 14-15 PSI at WOT. This will great extend the life of the VP44 because it keeps the electronics cooler longer and keeps the rotating parts lubricated properly. So please people let the facts and information from the actual designers of the injection pump (Bosch) and engine (Cummins) provide you proper information for your fuel system for your engine. Don't be swayed by performance shops claim of high horse output with little fuel pressure. As I proved right here doesn't work for the longevity of the VP44 injection pump... Another thing to bring up there are people that are increasing fuel pressures above 20 PSI. Please don't do this. The return port leaving the VP44 pump isn't very big at all. The return port is on the left and supply is on the right. As you can see increasing fuel pressures above 20 PSI put you at risk for shaft seal failure. Increasing the pressure above 20 PSI isn't going to improve the return flow. I say stick with the 14-20 PSI pressure range for seal safety. Additional Information (About Maximum Flow Rates) Here are some calculated flow abilities of the stock fuel system vs. 1/2" big line kits. This is not calculating bend, turns, offices just straight flow for open end plumbing and this is a rough calculation. Pipe Size Gallon Per Hour Flow Rate Gallon Per Minute Flow Rate 6mm ID pipe 75 GPH @ 15 PSI 1.2 GPM @ 15 PSI 1/2" ID pipe 570 GPH @ 15 PSI 9.5 GPM @ 15 PSI Use The banjo bolt Shrader valve to test for fuel pressure, Item 3 in the above diagram. If you have a 98-99 truck the port might be on top of the fuel filter housing. You can see the 90* bend fitting coming out of the top of the fuel filter housing in the below picture. Install a Shrader valve and test from there. I'm hearing of tales of shops, mechanics, or dealers doing the old hook up the fuel pressure gauge and only checking fuel pressure at idle. This is wrong. Because I've seen lots of cases where fuel line restriction, fuel filter plugging, gelling fuel and other thing causing fuel pressure to drop out under load. Like this video from a friend of mine, you'll see he's got awesome fuel pressure at an idle (where most shops gave him the green light). However, what the shops did not test for is WOT at highway speed, and you'll see in the video, he can pull way down to 0 PSI. Anything under 14 PSI is a concern... Anything under 10 PSI is a serious problem. As for having a gauge in the cab all Dodge Cummins trucks should have a fuel pressure gauge in the cab. Because like you seen bench testing with an idle pressure is meaningless if you can't see the WOT pressure at highway speed. View full Cummins article
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My truck is a 2001. I have an older AirDog, and an ISSPRO electric fuel gauge. The issue I'm having is that when I first bump the ignition I get about 15-16psi of fuel pressure. Then running, or even if you let the pump shut off and then rebump the ignition, the fuel pressure goes up to 26psi. I really need to get my test gauge on it, but two different sending units and gauges have been put on it, and both read the same. I was wondering if anyone has any ideas of what I should check? Is it the AirDog, that's marked as being regulated at 15 psi, did I screw up with how I installed the gauge? Any input would be greatly appreciated. Also, the AirDog was on before I pressure gauge was (I know shame on me....), so I do not know if this is a recent change or has always done it.
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Truck died and will not start. Checked fuel pressure, 10 psi. Decided to change fuel pump to Airdog FRRP-100. Now with Airdog FRRP-100 pressure is at 10 psi (which I believe is low for priming pressure) with Airdog pressure screw all the way increase via screw. Cracked VP44 return line banjo bleed than tried to bleed at 1,3,5 but pressure was low very little flow. What would cause the pressure to be so low? There seems to be air still in the lines and can't seem to get it out- think be cause the pressure is so low. I did change the VP44 out in December & fuel pump (Airtek) ~year ago any suggestions?
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I have a 1999 dodge ram 2500 with 5.9. I had purchased a quadzilla tuner and I want to use the fuel pressure monitoring with the programmer. Does anyone know a part number or where I can get a sending unit that will work with this? Also my low fuel pressure warning kit I installed stopped working. I grounded the wire that goes to the pressure switch and it lights so I know the switch is bad. I just need the switch but can only find new kits. thanks
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I have a 98 cummins 24v just turned 92000 miles, stock as far as i know. It sis come with 2 gauges, boost and fuel pressure, though itès only 15psi. It used to bury the needle just after startup. But recently, on a fifth wheel trip to the southeast, it started at about 9 psi and slowly rose to about 14 psi. It was shortly after a fiilup so i thought it might be bad fuel, so i added some diesel kleen in the white bottle and things seem to improve somewhat. I continued on to cold Canada, where i am cuurently at a friends place and the fifth wheel is sitting in a public parking lot (with permission, of course). Yesterday I started it up and it was at 6 psi, and rose slowly to 12. I changed the fuel filter, but it didn't help.This morning I had to move the truck and it was even lower at about 4 psi. The truck has run ok all along, no hard start, no white smoke, no loss of power. However, at about the same time the tailpipe began making a rattling noise at idle. Don't know if that's related or not. Does anyone have any ideas or suggestion? I'll appreciate any help i can get.
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I just replaced my VP and although it starts much better, there is still the 5-8 seconds of cranking to get her going.... I have read that the fuel pump should not be running while cranking, but I'm pretty darned sure mine is...I don't want to hurt this VP. Should my FASS150 turn off while cranking and then pump once it fires up????I'm jealous of Mike's video where his truck fires in just 3-rotations....
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Specifications Here is a copy of the fuel system specifications from the Dodge Factory Service Manual. Fuel pressure Normal fuel pressure should float about 14-15 PSI running down the pavement. Should never fail below 10 PSI at all. Here is a colorized fuel pressure gauge to give you a clue of the fuel pressure span you want. You want the needle to stay in the green at all times. Yellow zone is a warning that you should check the fuel filter, lift pump performance, overflow valve, etc. This is undocumented maximum pressure is 20 PSI. Now take notice to the overflow valve is set for 14 PSI so excessive pumping of fuel does nothing for performance except create more heat for the fuel, which in turns reduces the cooling ability of the fuel and adds more stress to the lift pump. So a little extra fuel pressure is a good thing because it insures the VP44 stays cooled and lubricated properly. But excessive fuel pressure will heat the fuel and reduced the cooling ability of the fuel. Now always remember that the only lubrication the VP44 will see is the fuel itself so if you don't have enough fuel pressure it will cause damage to the VP44 injection pump. It's like the same as running the engine with low oil pressure it will continue to run but the damage to the engine will occur. Or in this case the VP44 which happens to be about $1,200 to replace. Pressure Drop Amount of fuel pressure drop between idle and wide open throttle. 2-3 PSI drop from idle to WOT is normal. But 5 PSI or more pressure drop from idle to WOT is pointing out a failed lift pump, plugged filter, and/or plumbing restrictions. 2-3 PSI Is NormalDropping more than 5 PSI is pointing towards a failed lift pump, plugged filter, or restrictive plumbing.Just to show you the difference in the stock plumbing which is 6mm ID plumbing and most performance pumps come with 1/2" ID plumbing. These pictures will give you a idea... First picture is a Big Line fitting over the top of the stock plumbing. Then the second picture compares the stock 6mm ID steel lines to a 1/2" ID Big Line hose. Here is a short video of stable fuel pressure from 55 MPH to 70 MPH at WOT. Cranking Pressure Test Here is a simple test on how to do the test for cranking fuel pressure. Pull the fuel pump relay in the PDC and then attempt to start the engine. Pay attention to the fuel pressure gauge during cranking. Be aware this test will trip a P1689 code and light the CHECK ENGINE light. Excessive cranking pressure can lead to difficult starting problems. Difficult Starting While Hot This problem is caused by a VP44 with a torn diaphram internally. This damage is typically caused from a VP44 that was operated at below 10 PSI for extended period of time. So technically you should replace the VP44 to repair the damage diaphram but most rig up a oil pressure switch or a starter delay relay. Here is my idea... This will cause the lift pump to remain off during the period of timing the starter is operating as soon as the key is released the lift pump will function normally and remain controlled by the ECM. Suggested Lift Pump Replacement You should replace the stock fuel system completely being that it cannot supply enough fuel for even stock requirements without causing damage to the VP44 injection or adding stress to the lift pump. The pumps I suggest are proven and come with a lifetime warranty. These pumps come with a full kit and replace everything from fuel tank to VP44. [*] AirDog 100, 150, or 165 [*]Raptor 100 or 150 [*]FASS 100 or 150 I don't suggest these pumps... Because they don't address the pump location, plumbing restrictions, or come with much of warranty. [*] Stock Carter or Carter Campaign Pump (4090046) [*]Holley Blue or Holley Black [*]FASS DDRP [*]AirTex
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Got a p0216 code on the truck. :confused: Sounds like the pocket book is getting a hole in it. Thanks for all the help.
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My truck is having a hard time starting. When idling the pump pressure 14. When going 70 it is 11. When trying to start it is 0. I now get the p0216 code and 1693 companion code. It is possible low pressure set off the codes so let's hope that is the case. The codes came a few days after the hard starting started. I have a new oem lift pump. 730k miles.
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The 2kreeks hauler has been missing at hiway speeds 'cruise 50/65 mph' every other speed is ok. If truck is acelerating no problem, pulling hard 10k up everything nornmal. The lift pump was replaced approx 3500 miles with a generic AIRTEX BRAND. This was replaced during a oil change when I found out the new carter was starting to fail. Now with new instruments the fuel pressure at idle is 21.5lbs and wot is 16lbs. My basic idle time is approx 5mins and some time more depending on how long of pull and how heavy..Does this high of fuel pressure hurt the vp44?Could this high of fuel pressure cause the missing?Only codes showing with key trip, is 1693 which was left over from a p0122, which is gone now after replacing the apps.larry
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3 Questions: 1. I looked at the Pricol Optix 2" Fuel Pressure Gauge (Elec) 0.30 PSI (BLK) on Geno's Website. Is this what I need to safely monitor my fuel pressure? 2. Is there a less expensive gauge that would serve the purpose? 3. I have a test gauge that came with the installation of my Banks P/P. Where do I find the fitting to connect it to check my pressure? ThanksOld Fart Non-MotorHead
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I have an 01 dually,that I bought from my mother after my dad passed away last year from brain cancer. The truck had sat for about 8 months,and after I had driven it for about 4 months,the lift pump failed on the way home from work,and the truck died and I had to tow it home. I replaced the lift pump,but I still couldnt get it to crank and run, it was getting fuel to all but the #1 cylinder. I checked for trouble code but it didnt display any,because the engine light wasnt on. I bought a lift pump and replaced it. I still cant get it to crank,but I did get some codes this time,they are P-1693,P-1689 @P-0122. Is there something I did wrong or something else wrong with the truck,By the way the truck only has 53,000 miles on it,I'm stumped.
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I have a 99 5.9 with a low pressure fuel pump not working. I changed out the pump today (160 bucks)with a new one but still no work. I ran out of time today to check voltage on the pump but I think it is a shoe in that it is not getting voltage during crank. I tried the bump engine but don't start, to hopefully get the low press pump to initiate but it will not. I did get the pump to work once a couple months ago and I think it happened when I drained the fuel filter through the bleed valve on the filter. Then went back to crank and the pump initiated. When I swapped out the pump today the filter was drained but it still did not initiate. All of that leading me to believe that it was a random initiate that once that it did work as it is supposed to.I can either mist the turbo and the truck will start up and run great.I know not to make this a habit or stand near when I start. Basically mist trubo, replace filter, go to cab start.I also just finished (this week) a 1500 lock n stitch repair on a 17 inch crack in the block.So, now I'm trying to keep monies spent at a low amount. Just from a day of working on this problem I can already see 3 things I could buy that would cost a grand that I don't have. Code reader, fuel pressure meter, fass fuel pump, dealer repair manual.If I could get some help here in working out this issue I'd appreciate it.The truck is still a pretty nice truck so I'd like to get a secure fix on it even if it is a solid work around.I have already read on this forum such things as possible air leaking in, possible bad diaphram in injection pump with others issues on the low pump not chiming in.My questions are:1. Is the low pump working to keep the engine running when I have it running? Or can the engine run at full pressure with out that pump once started? This could tell me that the pump is working but there is a prob with the pump on start up.2. If I find no voltage then where do I go from there. What fuses do I check? I checked the relays titled fuel.3. What pins do I short to read out the codes on the dash and where can I find the codes for this engine? There are codes stored but I'm trying to keep from buying a code reader for the fact that money is tight and I don't know what I'll need to buy next.4, Would there be an issue with Wiring a new wire to the low pump that would initiate when the truck is switched on? Sounds like a jury rig I know, but it is just a matter of getting the juice to components in my thoughts.
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Ok guys here it is I got this code after I plug the OBD II scanner tool on this truck I just bought. The previous owner told me about this problem , when the truck is running at speeds of 60 o 70 the pedal wont respond and the speed goes down and I have to lower the speed by braking or putting it on neutral and then it will respond. What do you guys think?
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Ok gang! Going to make this as simple as possible. On another forum everyone is now believing that 5 psi is a good fuel pressure to run. This is being said by a supplier that sells VP pumps. Although the Dodge service manual says 10 psi is the minimum. I have recently had correspondence with Cummins on this topic and they say "10 psi is the minimum" for the engine. I want you all to know I run 17 psi and am HAPPY with this pressure. What do you feel is the proper pressure to run?
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So I finally ordered and installed my gauges. I got Isspro EV2 Black Face gauges, 0-30psi Fuel Pressure, 0-1600* Pyro, 0-100psi Boost. Installed and working minus the fuel pressure gauge. I just got the last piece of that puzzle so tomorrow that will be totally functional. After I grew the cahoneys to drill a hole in my exhaust manifold it was cake work. I spent a lot of time running my wires to keep them clean looking and safe. Spent a lot of time cutting and fitting my stock a-pillar cover to get the gauge pod to fit nice and flush and as close to factory as possible. I hate when people do sloppy installs. But they look great!Pics to come soon!!
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I have a triple gauge pod with speaker hole for my a-pillar. What three gauges should I get? I originally wanted trans temp, egt's, and boost. But I have been reading a lot about how important fuel pressure is to monitor also. What are you guys running? And what is the best combo set up? If I go with all 4 gauges, where would the best place be to placed the other one? Thanks guys.
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I HAVE A 98 24 VALVE WITH 165 k miles. I am getting a crank position sensor code set. This happens only near wide open throttle. The tach goes crazy and the check engine light comes on. when checked the only code is p0331. I have previously replaced the part but the code comes back. After doing a fair amount of reading I decided to check the fuel pressure. It reads 13 at idle and will stay there until i get close to 2500rpms or so at which point it will drop to around 8 pounds maybe. the needle flutters pretty bad. The truck also at that point runs like ____.So my questions are do I need to replace the crank position sensor , replace the lift pump, or should I do some more testing before I throw parts at the truck. I am not inclined to just throw parts at it. I bought the truck a while back at a decent price just to flip but I did not realize all the issues with it. It has a 53 block and has been used to tow as it has a goose neck hitch and was a ranch truck . I had to have the nv 4500 rebuilt. I might keep the truck if I thought the block would be ok.John
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First off, let me say that this forum has been very helpful before, but I just can't seem to diagnose the issue this time. Hopefully someone has an idea on how to fix this.I installed my 4 gauge Autometer digital set(Boost, EGT, FP, and Trans temp) yesterday. Everything went in smoothly. Went to start truck up, wont start. Thought ok probably the fuel pressure, so cracked one of the lines, got fuel coming out, closed it. Tried it again. Wont start.:banghead: The FP gauge reads 0 while I crank, is that normal, or will it not register until I start the truck up? Any ideas??? Thanks ahead of time!!
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My truck has been dead for a few days now and I was referred to this site for better, more useful help, so here goes... I was in the middle of a coolant flush, heater on full blast, truck was idling for maybe 20 minutes, then suddenly sputtered and died. It cranks but will not fire up. Throws a P0234 code for "overboost", however this seems to be irrelevant, as I was driving it unusually hard the night before, to check for oil leaks since I had just changed oil/filter. Anyways, the issue seems to be narrowed down to lift or injector pump, or both. Heres what I've done so far: added 5 gallons to fuel tank, primed pump 8 times, loosened injector line on one of cylinders while cranking and got some fuel to come out. However, even after priming pump, fuel canister is near empty, pointing towards LP. The next issue is figuring out how much, if any, damage is done to VP since this truck has 200k with no service records and I've only owned it 3 weeks. I've been directed toward 2 bluechip articles regarding some testing procedures that I will get to. I was referred here for some extra help and advice without the "pissing matches" on who's right or wrong.Also, when I crank the truck for say... 5 seconds straight, and let the key go, the pump whines pretty loud under me until I pull the key off. Not sure what means, obviously, even though it's making noise, it can't be pumping fuel can it? My canister would be full, but only has maybe an inch of fuel in it. It's a little late to go out and test anything now, but please share any info you might have for me in the meantime. Thanks guys
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A poll to help with quick look at vitals.
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So i got to thinking that having polls will help many make a decision or get a baseline of certain vitals on the cummins. Ill make a poll for a few things, it will help with troubleshooting as i see many times folks asking for "what range should i run" or "what is a good pressure" etc etc. I think these will be beneficial for all of us. Maybe Mike can make them a sticky so folks can get a quick look at vitals and what people run with things quickly.ill make the polls seperate from this thread.
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First new to site. I have another vp44 question (sorry). I replaced my vp44 back in oct 2011 and also added the raptor frrp pump and i made a big line from fuel filter to vp pump. both were purchased form thoroughbred diesel. At the time i was working out of town and wife was driving it when it did not restarting in the wendys drive through. so i had her tow it to a diesel shop to be looked at. them came back with needing a new vp44 pump. so i order the parts and installed them, got the truck running and drove it 20 miles or so. Got home it sat for 30min and went to start it and it took way longer then normal. So i thought the pump might be making to much pressure so i unplugged the cable to the raptor and the truck fired right up. plugged the cable back in and it hard starts. Crank pressure is 11-12. idle is 16-17 and wot 14-15. so i let the problem go as the truck manly sets and when I do drive it I let it run never turning it off, so today I drove it, turn it off and lets just say she got towed home will not restart. crank psi 12. Not sure but i think the vp44 has gone bad. have no codes. What do you guys think. Thanks for the help.
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