Been doing great ,a short trip to town and truck stumbles FP drop to5 lb and stop'd , i have relocated the fuel pump at the tank and have a big line kit just to let you know ,so i switch out the fuel pump on the side of the road and you can bump the starter and it take over half the cycle before the FP gage moves up to 12 lb if you watch it the pressure starts to drop " no start" vp lines are cracked open and no fuel is showing, is the vp pump gone again ? or is the draw straw sucking air ?

 

vp44

 

I was hoping someone wouldn't say that this will make #4..but is this the reason it's slow on build up pressure from the LP it's going right through the VP to the tank ?

 

Check codes with key trick.

 

I done the key trick and got ..P..ECU.and P..PCU

 

those codes sound like an electrical problem. maybe bad grounds? or even a fuse or relay? where is your FP gauge?

 

I checked the fuses and the relay's as best i could , i have a pressure gauge and it come's up to 12psi but it just want crank and i can't get fuel showing at the injectors ...i think it's shot !

 

Not saying it isnt the vp by any stretch but you might verify that the replacement pump is actualy working the way it is supposed to wouldnt be the first or second time one came bad out of the box. The ecm/pcu arent codes they are just stating that those two things were checked. They usually say ecu list the codes one at a time if any then say ecm done then moves to the pcm and does the same.

The fuel pressure dropping off once the fuel pump stops is normal.

Taking half the 30 second cycle to build 12psi might be kind of long so I would verify fuel pump. Maybe feed it from a can other than the truck fuel tank and see what happens. Could be a restriction in the tank pickup or filter screen in the bottom of the module or if a draw straw low on fuel. Could be a restriction in the line feeding the pump. If fuel pressure gauge is located between filter and vp double check the condition of the filter or just replace it.

You can also do a volume check on the amount of fuel the pump is supplying. Just undo at the vp dump it into another can and measure how much over a given period of time say 30 seconds. Dodge does have a standard for that I cant remember what it is but hopefully someone will remember or do a search it is probably here somewhere.

As mentioned previously checking the grounds and connections sure wouldnt hurt either.

You dont want to spend $1k+ to find out it is not the vp (not trying to imply you dont know what you are doing). It is certainly worth the time to double check those items. While not always the vp usually gives up a code or two or three.

 

Thanks Barry the LP is pumping good volume i checked that but iv'e tried to crank it yesterday several times with the injectors cracked open and i have yet to get any fuel to show , i can take a pump off in a couple of hours and let them check it but as you guys have said read the codes.... there were no codes .. this one has acted strange most of the time it's dead pedal for a while then NO start .

 

well if there is fuel in front of and not behind the pump then logicly it would be the pump.
however somewhere i had heard that minimum pressure for lift pumps was 17 psi. though that might be a specific brand. or in the 12v threads
is there a sensor that tells the vp to feed fuel?

some of the fellows in this thread are talkin about the electronics in the vp44; https://www.dieseltruckresource.com/...t-t304822.html

 

The vp has its own internal transfer pump. It is not up to the task of pulling fuel uphill for 15 feet though. (some other appilcations that use the vp dont all have an external pump the vp pumps its own). So if it is getting some pressure it should be able to run the truck.

There are certainly electronics in the vp that go bad. They just generally set a code as the ecm is monitoring it and getting feedback from it. Mechanically it can go bad as well obviously the rotor, plunger etc can get galled trashed whatever and then it cant provide the pressure needed to pop the injectors open to provide fuel in the cylinder. There is also an overflow valve atttached to the vp. Usually at least in mine where I have to replace mine the overflow valve was not included I had to reuse the existing one. (the overflow valve is located on the side of the VP at what would appear to be the return fuel flow. If that was stuck open it might be able to allow too much fuel to be returned to the tank. I think that valve is very early on in the fuel flow circuit of the vp even though it is on the return side. Might be worth looking at. Genos garage sells them relatively cheap as does cummins and the dealer albeit at a higher price.

If you are getting the classic dead pedal (truck is running and applying the accelerator pedal does nothing for a short period of time regardless of position and then comes back at some point usually within seconds) that really narrows it down to one of two things the vp or the apps imo. Typically on the vp that symptom is associated with the 0216 code but not always. The apps generally gives a dead pedal within a certain range of travel in the pedal but again not always.

Arent trouble shooting these fuel systems fun and a real character builder

 

It does sound like a bad VP44 to me, but the ECM and PCM codes are the ones that look strange. I just don't see how those would quit. I think, of the three, the weakest point is the pump unless your lift pump has stopped (which your first post seems to say with FP dropping before the truck died) and does not allow any flow through (you say now that it does provide flow, so that one is out).
I am guessing, VP it is. Here goes another $1k...

 

As you said Barry i see little discussion on the return line valve " banjo fitting " mostly on high pressure and Volume of fuel for cooling i did checked mine and it seems free with spring pressure ,the holes in that fitting are small and could be up grated to let more fuel pass under pressure this would help with cooling , while i was thinking on cooling a Heat shield between the block and the pump might be helpful ....just wondering .

 

Up date on my problem after taking the Pump to " Diesel Equipment Company " in Greensboro they ran it on there machine and it all checked out.... But suspected it was a short in the wire that is on the back side of the pump " it looked a little worn " and he says arcing could have happen , he repaired the wire and while i had it off new O rings in the head and diaphragm were installed $ 375 ...check those Wires Guys . Thanks for all the Help !