I had a guy call me today that has been having some trouble with his 24v and I wanted to see what the experts here have to say about it.

 

Here is a rundown of what I know about his issues.

A few months back he told me he was having a dead pedal issue and the shop the truck was at replaced the apps and it still did it so then they ended replacing the vp44 and lift pump. 

Now the current problem he has is the lift pump runs when you turn the key on but then once the truck is started it seems the lift pump shuts off and the engine will start stumbling and smoking.

 

I'm almost thinking it could be a problem in the ECM but I really hope for him that it's not.

I think there is a guy here that runs his lift pump off the alternator.  Not sure though. The best is directly off the battery controlled thru a relay by the ECM, but, it  sounds like the ECM is not functioning correctly. In my situation I would somehow by pass the ecm if possible... run off the battery with a relay controlled by oil pressure switch possibly.

 

Aside note..... does he have an aftermarket lift pump, no intank pump? With no banjo bolts and a Fuel pressure gauge? Good  aftermarket filter too? These items are important so you can maintain at least 14 p.s.i. of clean fuel at all times.

If the lift pump does not remain on after cranking that it is likely ECM.

 

Any WTS light issue? 

 

You might have them supply lift pump power directly and see if the issue goes away.   if it does it points back to the ecm.

Why does he think the lift pump shuts off once the engine is started?  I would start small by checking voltage and FP.  How is his filter?  Have him check his alternator for excessive AC voltage.

I had this problem after I changed my lift pump, so I would suggest a fuel filter change, and to check the lines.  Were all of the electrical connections tight?

sounds like the shop he took it to does not mind throwing some one else money at a problem. All good questions above that need answering to move forward. Trouble codes would be nice but if they were not cleared after all of that they could be deceiving.

Thanks for all the great input guys, I'll call him today and get some more info and see about going to check the truck out myself.

11 hours ago, dripley said:

sounds like the shop he took it to does not mind throwing some one else money at a problem. All good questions above that need answering to move forward. Trouble codes would be nice but if they were not cleared after all of that they could be deceiving.

Part of the problem too is these shops don't realize that Dodge engineers screwed on the fuel system and needs total revamping/ redo on it.

Sorry it took me so long to post a update, been really busy working.

I went and looked at everything on this truck today and the fuel pump was working as it should, and the truck idled fine but sputtered from a lack of fuel with any throttle, he didn't know when the fuel filter was last changed so I got one and put it in and she runs good now, problem solved.

I also checked for AC noise from the alternator while I was there to make sure it wasn't doing anything and it was less than .06v