The dealer diagnosed the injection pump to be bad. I replaced the injection pump and the truck does the same exact thing it did before. It will start and idle VERY rough, like a gas motor with a very large cam, but then it will die after about 5 seconds. You can start it right back up and it will do the same thing everytime. The tach reads rpm during this and pressing the gas peddle does absolutely NOTHING. I have bled and checked the lines, they have PLENTY of fuel at each injector. The lift pump is working....I'm stumped.

One thing I was thinking is the cam position sensor? Could this be a problem?


I can't beleive it isn't running any different than before when it had a bad pump. That's what has me stumped.

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And it looks like I just posted this in the wrong section. See how my luck is?

 

U got a fuel pressure gauge? If so what ya getting? Any Codes?

 

No fuel gauge and I'm not sure of any codes. I can;t get this truck out of my driveway to get it anywhere. I might have to go buy a code reader I guess. I just spent $1039 on the VP44 and $200 in batteries and I haven't fixed the problem yet. It's strange because I'm 99.9% sure the VP44 was bad and the dealer diagnosed it to be the VP44, but it didn't make a bit of difference with the new pump installed.

Also, I unplugged the cam sensor and nothing changed. No engine light and it still acts the same way. VERY rough idle for about 5 seconds and then it stalls. The ABS light comes on, but I don't think that's related.

BTW, this is a 1999 Dodge Ram 2500 with about 134k miles. Before this it was taken into the dealer and they "flushed" the fuel lines because that's what they originally thought the problem was. They also changed the oil, air filter, but I don't think they changed the fuel filter. I would suspect the fuel filter, but I know I'm getting enough fuel to at least keep it at an idle.

 

You should always change the LP with the IP. You probably have a bad LP and that's what killed your first IP and now possibly the second one.
Get a FP gauge on it ASAP!!!!!!!!!!!!!

 

Spend the money and get a good LP like a FASS or Airdog

 

For the record, the LP is NOT bad. It has PLENTY of pressure and the injection pump is pumping fuel about 100x as much as the old one was.

The lift pump is NOT bad. I will be replacing it as soon as the tank gets low, but right now I'm not touching it with a full tank. If the tank were lower it would have been replaced, but I can assure you it's NOT the lift pump that's causing this. I know it's easy to point a finger at that right now, but fuel delivery is not an issue anymore.

 

It's a 99, just stick a cheap gauge into the top left fitting of the FF housing and let us know what the FP is.
We're just trying to help. It may look like you have good pressure at the injectors but not enough.
Are all the lines at the head tight. I've seen this cause a rough idle too.
Do you have an in tank LP?

 

How do you know your LP is good bud?

 

I don't have a gauge and I don't know the exact pressure coming otu of the LP, but common sense tells me that when the LP is enaged and fuel is squirting out of the line at a steady, constant pressure like a fire hose, that means it's probably ok. Can we just ASSume the LP is good? If the LP is even close to being bad I'm sure I could visually tell by the gallons of fuel it spits out when it is engaged.

You can look at a tire and guestimate it has enough pressure to roll yourself down the road even though you don't have a gauge on it. I know it's a bit more technical than that, but if I put a gauge on it I'm POSITIVE that it will read within spec.

BESIDES the LP, is there anything else that could cause this? I'm 110% sure the LP that's in there is good as of right now. I will be replacing it once the truck is running and I can burn the fuel that's in the tank. Bad timing caused the truck to break down with a full tank.

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I have checked, cracked, bled and re-checked all lines and they are tight with no leaks.

The lift pump is in the tank on this truck. I suppose I will buy a gauge and check the pressure even though I know that's not what it is.

 

Ok, down to basics.

LP. It may or may not be bad but even if it were it would take time to kill a brand new VP, so that's not gonna be the issue here. Even if the LP was completely dead the VP will still pull the fuel it needed to run it would just be a pain to get it primed. If it's starting though then it has a prime.

Did you change the Pressure Regulator on the VP44 when you installed the new pump. If it is bad the VP will not hols the right internal pressure and won;t feed fuel right. It is the Banjo Bolt on the outgoing fuel line from the VP, it has a spring loaded ball bearing in it. This could be the problem.

Since you say that pushing the go pedal has no affect I would bet that you forgot to plug the APPS sensor back in when you put everything back together. Check this out. It is the plug that goes to the underside of the throttle assembly. It's easy to miss.

The other issue here is, are you sure you got the key way lined up exactly in the slot. It will go in wrong and the nut will suck it into place just like it's right. If you missed by even the smallest margin your timing is off and the new pump is now bad.

We'll start here and see what comes up.