VP44 cutaway and pictures

**tylerkck** · June 7, 2010

See attached file.

I'm trying to figure out the path of the fuel flow within the VP44 injection pump (IP). I'm interested in the slight possibility of additional cooling for the IP. Does anyone have any other pics or drawings or diagrams they can upload?

I've done a bit of research on forums and I've talked to BlueChip at lengths. The VP44's computer sits on top of a heatsink or is integral to it, this is bolted to the IP housing, and the diesel fuel passing under the heatsink cools the computer. There is a vane pump at the inlet of the VP44. The "ww.chinahanji.com" drawing is helpful. I'm thinking the area directly beneath the computer, adjacent to the inlet and outlet ports is a cavity and inlet to the vane pump. The fuel enters the cavity thru the inlet port, the cavity is pressurized to 14 psi via overflow valve (or pressure release/check valve, whatever you want to call it) that is integral to outlet banjo bolt. A portion of the fuel is taken from the cavity by the vane pump and fed to the high pressure rotary section of the IP, the rest is returned to the tank thru the overflow valve. This flow of fuel, most of which is returned to the tank is what cools the computer. Does anyone know what the bottom the computer/heatsink looks like?- is it finned or flat? The smaller cavity that the heatsink/computer also covers is shown with what looks like a wire ribbon passing thru and has a seperate gasket. Does anyone know if this is also filled with fuel? Please, are there any VP44 guru's out there that can correct me?

VP44 pics1.doc

**ISX** · June 7, 2010

Incredible document! With what you have dug up and what you and other people here know, there might just be a solution yet for the cooling issue. Moved this to 2nd gen 24V section. Keep up the awesome research! Hmm, look at the last post of the first page on this thread http://forum.mopar1973man.com/showthread.php/1656-VP44-Write-Up-Minimum-pressure-suggested... Ok, post #23 of that same thread on the second page has an even better pic of the flow. As far as I know, nobody has a pic of how the pump breaks down (the second pic of your document) so we're another step ahead in maybe being able to fix it ourselves. I know Mike is dieing to find out how.

Mopar1973Man · June 8, 2010

Here you go... http://www.turbodieselregister.com/user_gallery/displayalbum.php?&albumid=17275

**tylerkck** · June 9, 2010

Thanks guys for the links, very helpful.

See attached.

I initially thought the cavity under the computer/heat sink held the supply and return ports. Only the fuel inlet is connected to the cavity. The fuel enters this cavity makes direct contact with the computer heat sink and is forced thru the orifice (as shown in the 5th picture) to the vane pump and to....take a look at the diagram. BlueChip has said that the majority of failed VP44s is due to failed computers (at least with the later versions). The computers fail because they get too hot and/or because of heat cycling, in particular the lead-free solder connections are weakened by this. Chip noticed (I don’t know how) that the temperature gets the hottest right after shutdown….makes sense, because no more fuel is flowing thru the pump for cooling….when the IP is not turning no fuel will pass thru it. Chip is currently working on two things to remedy this; one modification will allow fuel to flow thru the pump (just the heat sink cavity) even when the IP is not turning, the other will allow the lift pump (LP) to continue pumping (and circulate fuel thru the cavity) after the engine is shutdown until the pump is “cool enough”.

Chip has tested different solutions to this problem in the past. He’s spent over $10k trying to move the computer, but electrical interference put that solution to rest. He machined and bolted another heatsink to the top of the computer, actually I think he machined a whole new cover with integral heat sink….said the temps underhood are too high to do any good. I''m not clear on how or where he measures pump temps to test his solutions.

I asked Chip if the current solutions he’s working on include adding another outlet port to the cavity, but he stopped me there with proprietary. I believe that is a good solution, especially if you can add the port to the opposite side of the cavity….if it is feasible given the layout of the IP. I’m thinking you would attach a regulator on this added outlet port and maintain the cavity to say 17psi and use a higher flowing LP. I have an AirDog LP/filter assembly, I believe rated at 95 gph with big feed line, stock return line, not sure if I got a different pick-up. As it runs now, most of the LP flow is returned to the tank right from the pump exit, the fuel returned from the IP and injectors shouldn’t have change much, if at all, with the addition of the AirDog. Adding an outlet port with regulator to the cavity would allow much more of the LP flow to actually go to and cool the IP computer.

VP44 pics2.doc

**tylerkck** · June 9, 2010

I’m not sure if this should be a separate Thread, but….

My stock LP and consequently my stock IP failed at about 57,000 miles (’06-’07?). The IP and LP were replaced under warranty. Soon after, I dropped the tank, removed the replacement LP, and installed the AirDog. I have had no problems since, now with +130,000 miles. I’m doing this VP44 cooling research because I’m considering converting my truck to run on straight vegetable oil (SVO). The viscosity of VO is too high at ambient temps and must be heated to thin it down to that of diesel. Trying to remove heat from the IP isn’t going to happen with hot fuel, 160F up to +190F.

First I want to say that I have found only 2 guys that run SVO thru a 1998.5-2002 Dodge Cummins with “success”. I’m communicating with one of them (cumminscanuk on burnveg.com). He lives in central BC with cooler ambient temps, his waste vegetable oil processing seems to be up to par as well as his truck’s conversion set up. He has a ‘98.5 and has only been running SVO for 2 years, about 17,000 miles, with no problems, no error codes, all good. The other guy I heard about thru the grapevine, supposedly he has been running it thru his VP44 Dodge for about 5 years and had to replace the IP once at some point, maybe at 4 years. Needless to say, running SVO on this type of truck is risky business. Does anyone else have experience with running SVO thru VP44’s or know someone they can put me in contact with?

I’ve dreamed up some other IP cooling schemes that don’t use fuel to cool, but before I put any more effort that way I need to try to find answers to a couple of SVO/VP44 hang-ups. The VP44 has a temperature sensor integral to it. My Edge Juice with Attitude can display this temperature, I’m not sure if I’ve ever seen it higher than 120F. Edge calls it the fuel temp. I read in my factory service manual (FSM) that if the fuel temperature gets too hot an error code (P0168 or P1180) will be logged and the truck will be derated.--Does anyone know what that temperature is?- it can’t be 120F, because I’ve never seen the codes. Does anyone know if this was a safety feature added to later trucks?- say from 2000 and on? If someone has a FSM for an earlier truck (1998.5 would be best), we could compare the error codes given in your section 25 to my 2002 FSM. MoparMan, I checked your section 25 (2000 year, right?) that you posted and there are some differences but the P0168 and P1180 codes are listed there.

Also I read somewhere on the internet that the maximum fuel inlet temperature Bosche allows for VP44’s is 158F, beyond which diesel fuel loses too much lubricity. I also read that the max was 98F, beyond which not enough cooling is provided to the IP by the fuel.

**ISX** · June 9, 2010

Just dug this up from cummins about the temp sensor in the VP44. P0181--Temperature sensor's reading correct (greater than -45°C [-49°F] and less than 130°C [266°F]). When a defect occurs within the VP44 controller temperature sensing circuit, the controller defaults to a temperature value of 75°C [167°F]. If this is the temperature's reading indicated on the monitor screen and this reading does not vary with changes in the coolant temperature, then the VP44 is most likely malfunctioning. The circuit for this fault code is contained within the Bosch® fuel pump control module.P0168--This fault code is typically set when the VP44 fuel pump controller communicates to the engine ECM that the fuel temperature measured in the fuel inlet to the pump (VP44 temperature sensor) exceeds the allowable threshold value (93°C [199°F]).So I guess there is an ECM threshold along with internal VP44 threshold.

**tylerkck** · June 9, 2010

SOB! I just spen 1/2 hour replying, hit submit, asked me to log in again, my reply is gone! I'll reply later. Thank you so much ISX, that is exactly what I needed!....why don't I feel releived?

**ISX** · June 9, 2010

I noticed it does that if you wait longer than 15 min to do something on the site and haven't hit the check box that logs you in automatically. After 15 min the server marks you as inactive, so you basically just logged out. So to fix it, you can either hit the box that remembers you when you log in so that it automatically logs you in anytime you do anything, or you will just have to highlight and copy your reply before you submit it so that if it has logged you out, you can simply log back in and paste the reply. Sorry you had to find out the hard way

**tylerkck** · July 1, 2010

According to BlueChip, Bosch came out with a more resilient computer for the VP44. I wanted to find out if I had this model. I guess the part numbers are the same and the only way to know for sure is to take the IP apart. The upgraded computers have a larger heat sink that protrudes down into the inlet cavity more. Chip isn't sure if Bosch made other improvements to the computer. I'd like to run some shadetree tests using the fuel temp as given by the VP44's sensor and the actual fuel temp. I want to draw coorelations between inlet fuel temp, return fuel temp and VP44 fuel temp while running and after shutdown. I might test some cooling ideas too. The transmission temp sensor from my Edge Juice Attitude module is good, I guess becuase it read 0 deg F instead of 7 F.....Edge wants me to send in the module for service at $99 to fix it. I hate dealing with electrical type problems, but I'd like to troubleshoot it, anyone know how to check the wiring of these sensors?- is there supposed to be 12V going to the sensor? What about those trouble shooting LED lights on the Edge module, will they tell me something?

**tylerkck** · November 16, 2010

I just wanted to give those interested a shout.... I got the Edge module fixed (trans temp now reads out), I installed the trans temp sensor in the fuel line a couple feet before it enters the IP. I'm seeing that the IP temp reads 15-40F higher (preliminary findings!!!) than the sensor output. I will also put the sensor on the IP return. Again, I'm mainly doing all this to determine if I want to run SVO and what I can do to insure a successful reliable conversion. Unfortunately, I didn't get this work done before cold weather got here; temps while running and after shutdown with hot ambient temps are crucial, so I wont be able to draw any real conclusions until summer hits.

--- Update to the previous post...

Has anyone verified that running higher fuel pressure to the IP gives more fuel return to the tank? Has anyone verified that more fuel return equals more IP cooling?

**ISX** · November 16, 2010

From what I saw with John's truck the VP has no issues when you are driving, but when you turn it off the pump gets up to 50F hotter than ambient. I think it even got to 60F over also. It remained hot for hours.. Because it is aluminum, it easily takes the heat from the block so as long as the block is hot, the VP remains hot too.I think that is why people get in their trucks and they are messed up, because the VP heated up and the solders melted. Now Mike had a valid point that electronics that are off can stand much higher temps, but I still don't know about the solder.

**volkswagon** · November 16, 2010

Has anyone verified that running higher fuel pressure to the IP gives more fuel return to the tank? Has anyone verified that more fuel return equals more IP cooling?

Mopar1973Man · November 16, 2010

I know a minimum of 15 PSI will keep the overflow valve open while the engine is running but very little to no fuel will flow through the VP44 pump even at 17.5 PSI with the engine off...

**guesswho512** · November 16, 2010

i remember once when ISX was experimenting for faster warm up times. he had taken copper tubing and ran it around his exhaust, i memory serves. the problem was that the coolant was around the heat source long enough to pull much heat from it. maybe the VP44 is in the same boat. fuel pumps thru it so fast, it doesn't have enough time to pull heat from the pump.

**ISX** · November 16, 2010

i remember once when ISX was experimenting for faster warm up times. he had taken copper tubing and ran it around his exhaust, i memory serves. the problem was that the coolant was around the heat source long enough to pull much heat from it. maybe the VP44 is in the same boat. fuel pumps thru it so fast, it doesn't have enough time to pull heat from the pump.

The exhaust thing didn't work worth a damn. I ran a loop inside the 5" downpipe so the gases were all around the pipe heating it up but I didn't see any difference in warm up time. I like to think I did but in actuality I don't think it did anything. The coolant moved through the pipe too fast to get any significant amount of heat. It needed more time to soak the heat in. The VP doesn't heat up at all when the engine is running. John's truck had the edge juice which taps into the VP's fuel temp sensor so I was able to see fuel temps and as long as the truck was running the fuel temp was fine. I do wonder about long hauls where the tank gets warmed up from the constant recirculation through the VP. When I turned the truck off was when I saw the huge temp spikes from the latent engine heat being absorbed. When I started it, temp would go right back down, though slowly. Thing about cooling is although it was going to fast to warm up with it going through my exhaust, it works in reverse on the engine block. If you take the thermostat out your engine will never heat up, the coolant flies through the block but because the block is big, the coolant runs through it long enough to take all its heat, then the radiator is so big that it easily rids the heat. I did this once and went 20 miles and at the end of 20 miles it was at maybe 120F. The thermostat actually restricts flow because it would overcool without it.

**guesswho512** · November 16, 2010

I’m not sure if this should be a separate Thread, but….

in my opinion...this should be a separate thread. i'm sure that you and the rest of the group probably have good info pertaining to this, but will be lost in this thread. making it hard to find/search for.

My stock LP and consequently my stock IP failed at about 57,000 miles (’06-’07?). The IP and LP were replaced under warranty. Soon after, I dropped the tank, removed the replacement LP, and installed the AirDog. I have had no problems since, now with +130,000 miles. I’m doing this VP44 cooling research because I’m considering converting my truck to run on straight vegetable oil (SVO). The viscosity of VO is too high at ambient temps and must be heated to thin it down to that of diesel. Trying to remove heat from the IP isn’t going to happen with hot fuel, 160F up to +190F.

First I want to say that I have found only 2 guys that run SVO thru a 1998.5-2002 Dodge Cummins with “success”. I’m communicating with one of them (cumminscanuk on burnveg.com). He lives in central BC with cooler ambient temps, his waste vegetable oil processing seems to be up to par as well as his truck’s conversion set up. He has a ‘98.5 and has only been running SVO for 2 years, about 17,000 miles, with no problems, no error codes, all good. The other guy I heard about thru the grapevine, supposedly he has been running it thru his VP44 Dodge for about 5 years and had to replace the IP once at some point, maybe at 4 years. Needless to say, running SVO on this type of truck is risky business. Does anyone else have experience with running SVO thru VP44’s or know someone they can put me in contact with?

I’ve dreamed up some other IP cooling schemes that don’t use fuel to cool, but before I put any more effort that way I need to try to find answers to a couple of SVO/VP44 hang-ups. The VP44 has a temperature sensor integral to it. My Edge Juice with Attitude can display this temperature, I’m not sure if I’ve ever seen it higher than 120F. Edge calls it the fuel temp. I read in my factory service manual (FSM) that if the fuel temperature gets too hot an error code (P0168 or P1180) will be logged and the truck will be derated.--Does anyone know what that temperature is?- it can’t be 120F, because I’ve never seen the codes. Does anyone know if this was a safety feature added to later trucks?- say from 2000 and on? If someone has a FSM for an earlier truck (1998.5 would be best), we could compare the error codes given in your section 25 to my 2002 FSM. MoparMan, I checked your section 25 (2000 year, right?) that you posted and there are some differences but the P0168 and P1180 codes are listed there.

Also I read somewhere on the internet that the maximum fuel inlet temperature Bosche allows for VP44’s is 158F, beyond which diesel fuel loses too much lubricity. I also read that the max was 98F, beyond which not enough cooling is provided to the IP by the fuel.

the computer on these trucks use speed/density to determine the amount of air going into the motor. it then figures out how much fuel to inject based off of the air flow. but we(and the engineers at cummins) know the volume and corresponding energy content of a gallon of diesel fuel varies according to its temperature. Warmer fuel has less energy per gallon than cooler fuel. so the VP44 uses fuel temp to inject the proper amount of diesel to promote good combustion AND to meet emission standards(ie less smoke). (if my memory is correct)the ideal temp for our motors is around 90*F - 95*F

From the service manual.

When the temperature is below 45 ±8 degrees F, the temperature sensor allows current to flow to the heater element

warming the fuel. When the temperature is above 75 ±8 degrees F, the sensor stops current flow to the heater

element.

I would think if your getting hot fuel in the summer a cooler may not be bad, but you would want to bypass it in the winter.

I am wanting to add another heater to my first filter, Fleetguard makes a 300w 1-14 sandwich heater with the same thermostat at the OE heater.

did you do the sandwich heater?

DTC P0168 is for the fuel temp sensor circuit indicating high fuel temperature. ( above 122* C ; 252* F)

this thread is about a 04 duramax(using a CP3 injection pump), but is the only place that said at what temp P0168 is set off at. P0168 could be set off at a different temp for our trucks.

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