Cummins won't start when hot
 

The truck runs great and starts perfect when cool, but run it for a few minutes and it won't start once I shut it down.

I have replaced 2 lift pumps, 2 injector pumps, MAP sensor, and fuel tank pick up and filter, the only thing accomplished is messing up the fuel guage. Now I run out of fuel at a 1/2 tank.

A match and 20 gallons of gas are starting to sound good and cheaper.:argh:

** Please post questions in the correct forum **



1) Do you have a fuel pressure guage - absolute must on a 24V. Truck shouldnt leave your driveway without it.

2) Stock lift pumps are junk - dont waste your money on them

3) Have you scanned for codes?

No guage, but will get one.
Code machine lights like a christmas tree, but did not get them from the mech

Hard starts when warm are one of the classic signs of VP-44 failure. Notice and white smoke (when warm)??

Need codes if you are looking for advice. Good luck.

need to check fuel pressure

codes are going to be a must. it sounds like the vp has gone bad. throw the stock lift pump away and get an airdog and a pressure gauge.

Hard hot starts are the classic 2nd step of the vp44 - first step stock lift pump fails then without pressure guage - the injector pump vp44 starts hard starting then soon wont start at all. Once you put on guage get an airdog or fass and you will be a happy man. BTW if you need to change out the vp44 (you will) I have the tool to remove it and will loan it too you if you promise to return it. It is really kinda fun to do but can be stressful too. Also the screen on the fuel tank pickup bottom is really restrictive - engineer something better- I used a much larger heavier duty screen after the aftermarket lift pump install.

It was the VP44. Thanks all. I don't know why or how I got 2 bad ones in a row, but I know why I have a new mechanic.

good to hear. glad you got the beast running

Did you order a fuel pressure guage?

Hot start problem usually point to a VP44 diaphram issue... Way to check is disconnect the lift pump power. If it starts easy then you know the fuel pressure is too great at start up. You need to build a lift pump relay to hold the power off during startup. :w2:

is there any other way to remedy the diaphram issue other than replace the vp?

Or you could do one of two other things:

download a smarty
relash the PCM at the dealer

Both of these will shorten the lift pump run time prior to starting, making it easier on the VP.
Smarty is free if you know someone with one you could borrow. Dealer is the last resort, of course.

No way to just fix the diaphram and on top of that the steel plunger was rattling around inside the aluminum?? cant spell" housing and this alows fule to pass by the plunger. Problem here is the timing of the vp is controlled by the fule pressure and since some is now sliping past you probley have a p216 timing coad. Iv talked to alot of places about their reman vp and the best iv found is blue chip diesel look them up and at least read what they have. all they do is dodge fule systems. i like to stay loyal to my locals but not with the vp i got:c:

make the pump only run with switch on and not while cranking. you can wire to a window motor since they stop when cranking.