A few months ago I bought a 1997 dodge dually with a 5 speed and a gear vendors behind it. The truck had threw a rod and destroyed the injection pump and block when it let go. The main reason I bought the truck was to throw another engine in it and get it going again. I bought a so called "good engine" and tested it out of the truck just to make sure it ran. It seemed to run fine but I couldn't test how the engine does under load. So I put engine in and hooked everything up, got it primed and it bogs down under load. I tried running it out of a bucket trying to isolate the problem and it didn't change a thing. So I put a little air pressure on the fuel inlet and saw fuel/air pukeing out of the little rubber elbow between the fuel heater and lift pump. So I thought that would fix my problems but it didn't do anything! So then I did the fuel heater delete and it changed nothing. I lokked everywhere and I can't find a leak anymore. It will hold a prime sometimes and othertimes it won't. When I prime it it will run like a champ at idle and under 1500 rpm. No missing or stumbling. If I rev it up to 2000 under no load it will stay there for about 15 seconds then it falls on its face and when I crack a line on the injection pump there is air/fuel coming out. My question is, is my injection pump bad or could it be something else? I also just put a new lift pump and fuel filter on. The fuel filter I got doesn't have the water in fuel sensor because I thought it may be getting air there.

 

Sounds like the Lift pump is suckin air through the pick up side of the LP ... pull and replace that pick up line and see what that does ..

Keep posted ..

 

Agreed sounds more like lift pump issues instead of ip.

 

Suction and the possible loose or leaking fitting = air in fuel ... if your looking to upgrade, maybe even goin to a air dog or fass set up .. Of course thats if you plan on going for some good size HP #'s ..

 

Ok, so I replaced the pick up tube I have that I am using to run it out of a bucket and that did not change anything. I am going to try feeding the injection pump straight out of a bucket, bypassing all the filter and lift pump stuff. I will hook up a electric fuel pump and an inline fuel filter while running it out of a bucket. I just need to get another banjo fitting so I can bypass all the stuff. Thank you guys for the help! Will keep you posted on what I discover.

 

Sounds like a good idea .. Fuel pressure should be 30-35 psi .... dont push it too much further than that ... dont want the IP to start leaking ...LOL

 

Well tonight I tried fueling the injection pump bypassing all the filter and lift pump nonsense. I had a small fuel pump laying around and thought I would go ahead and try that. It was rated between 7-10 psi, i know that is a little low for the IP but thought I would try it anyways. Well I hooked a inline filter and the pump up and tried it. No go. It sputtered and would run really rough for about 10 seconds and die. Then let it rest for 30 seconds and try it again and it would do the same. Looks like I need to find a little higher pressure fuel pump. Right?

 

I would not be trying to run on pressure that low at all. My understanding is that low pressure is as bad for the IP as too high. I would look for a pump that can put out at least 30 PSI and go from there. The issue is that most electric pumps that can do that are not cheap by any means. If you had a regulator that you could hook up, I would say get your hands on a pump from a Powerstroke, but they put out over 70 PSI so they have to be regulated.

 

Would a lift pump work from a 2nd gen 24 valve? What kind of pressure is that putting out?

 

the vp pumps only need like 15 psi or somethnig to that degree, but the P pumps like 25-35 , no more than 40 , at that point your pushing you luck ...