Engine/Transmission (1998.5 - 2002) Still have hard start with new VP44

[GatorRam]

Put in a new pump last Thursday after having the hard start when warm problem. For the first couple of days it fixed it but now it's back. It's not as bad and it's not happening every time but it's back. Anybody have an idea what the heck is going on? It's kind of depressing dumping that much $$$ and nothing getting fixed. What other components, if any, could be the culprit. Has this happened to anybody else?



Thanks,

Adam

 

[GregFisher]

Did you install new lift pump, how are your batteries, any codes? Is it still just a hard start warm. need more info.





Thanks, Greg

 

[GatorRam]

I've got 22psi fuel pressure at idle, about 18-19 cruise, and I can suck it down to 14 wot so I don't think I have a problem there. This is the third VP on this truck and I've never had a VP related code. As far as the batteries go, I replaced them both two years ago and they seem fine. I'm just baffled with how it was fixed for a few days and now it's back.



Adam

 

[MKizziah]

Gator,

I just went through a R&R on my VP44 and FASS install. I did some fuel pressure testing and found some interesting results. If I cranked my fuel pressure up to about 23-24 psi. it wouldn't start . It would also kill the engine @ 22psi if I'd start it at 15psi and crank it up to 23-24psi. Over pressure to the VP44 I'm assuming. I set it @ 12psi and it will drop maybe to 11psi WOT. 12psi is spec. and with the FASS there is more fuel volume delivered @ 12 psi that I'd ever need. Over 1. 2 gpm.



Just a thought... .

Cheers,

Matt

 

[Steve St.Laurent]

When I talked with Dodge and Cummins when I put the pusher pump on my truck way back when they said that anything over 7 psi when starting could cause a hard start problem. On my truck if I crank it while the pumps are running it has to crank for a bit before starting. If I wait until the pumps turn off and then crank it lights right off. Are you waiting until your lift pump/pumps stop before trying to crank it?

 

[GatorRam]

I have thought of this also. I've tried all different types of starting methods with the same result. If I wait until the pumps quit running and then crank my FP gauge will show 15-16psi WHILE cranking. It always does this no matter what. I can't remember what I was getting while cranking with just the stock lift pump because it wasn't an issue at that time. While the high pressure thing could be what is doing this, wouldn't that mean that it would make it hard to start when cold also?



Adam

 

[MKizziah]

While researching the same problem I had, hard start when warm, I came across a couple of other low $$ solutions, One was the camshaft posistion sensor $50. Also the Crankshaft posistion sensor $50. I swapped both neither fixed my problem.



A terrible thought is maybe you have a bad rebuilt VP44. . I've read that one too, here on the boards. .



Good Luck,

Matt

 

[CStewart]

Hard start

I had a hard start when warm problem on my truck after I put the FASS on it. There was another thread that said that there was a reflash for trucks that had a hard start when warm problem. I had it done and it fixed mine, the only difference I can see after the reflash is that the lift pump or FASS doesn't start until after you hit the starter. Before the reflash the FASS would start pumping as soon as you turned the key on. From what I have read the VP-44 doesn't like a lot of pressure especially when the engine is warm.

 

[djacy99]

There is a valve on the return line at the vp. Is it going bad? Did you check it for dirt? It has a small spring and check ball built inside. This valve is the banjo bolt that fastens the return line to the vp. A quick check, next time it starts hard plug this port and try starting again.

 

[GatorRam]

Both times that I have swapped pumps I took out the bolt w/the valve and blew it out with air and cleaned it up. It looked fine. Has anyone else had the reflash done? Basically this just eliminates the short prime cycle? I don't like taking my truck anywhere near the local dealer but if it might help it might be worth a shot. I have also thought of the crank/camshaft sensors but I hear that you will see some erratic movement of the tach as a symptom of them going bad, which I have not seen. Thanks for the help so far, keep it coming!



Adam

 

[GregFisher]

anything more than 14 psi inlet pressure will cause a hard start more noticeable when hot.



thanks greg

 

[GatorRam]

Is anyone running a fuel regulator on their pusher pump setup. If so where did you get it?



Adam