Engine/Transmission (1998.5 - 2002) Engine missing/sputtering(long)

[shawn huizenga]

Hello everyone, this is my first post here, but I have been reading the forums for quite some time now. I'd like to start off with a little background on my pickup. Its a 99 3/4 ton with a 5 spd, 87,000 miles. I've only owned it for the past 10000 miles, and am the second owner. Up until now this pickup has been absolutely dependable and hasn't so much as missed a beat. A new fuel filter was put in when I bought it, and I had the lift pump replaced under warranty about 5000 miles ago, and it still has good fuel pressure according to my gauge. The symptoms are this, I'm driving along at about 30 mph and it starts to sputter a little, but comes out of it. At that point I'm on the frontage road just getting ready to pull onto the highway, so I get it out on the highway and accelerate normally, everything good. Once to speed I cruise for about a mile and decide to goose it a little and see if it will act up for me again and it does, but this time it sputters for a little while and dies. I was cruising on top of the valley and had enough speed to coast to the bottom. Once at the bottom I shut the key off and back on to start it, cranks for a short while and finally takes off. I ease it back home and it starts doing the same thing as I'm pulling back into the driveway. I decide maybe its the fuel filter so I took a different vehicle into town and got another, put it in bled it and the pickup took right off. I figured the problem may have been solved at that point so I decide to drive it to our farm about 15 miles away and it ran perfectly all the way there, nothing I did could make it act up. I shut it off to go in the house for about 6 hours, come back out and it fires right up. I went back inside for a couple minutes to get some things and come back out, it was still idling fine, but while loading my stuff in the passenger door it starts to sputter a little to the point where I thought it was going to die but it recovered on its own and came back up to a normal idle. The thing I did notice while it was sputtering is white smoke(raw fuel type smell) coming from the tailpipe. I'm left wondering what the heck the problem could be, and sure hope I can find a remedy before I actually need it to be dependable later this week on my trip back to college. Any ideas are very much appreciated. I am confident you guys will be of great help on this. Thanks in advance.

 

[Amianthus]

Sounds like you could be in the same boat I'm in. Mine was doing similar stuff. Here's my symptoms: Hesitation, lack of power, lack of throttle response, stalling, misfiring, hard starting (occasionally). Testing revealed that my APPS was working just fine, but my FMS is telling me that the pump signal still isn't right. That and the misfiring leads me to believe that one of the solenoids internal to the pump is failing. So the VP is slated to be replaced this week on my truck.

I don't know if that's exactly what's wrong with yours, but I'd be leaning that way.

 

[shawn huizenga]

The VP is a definite possibility, but the thing is when it runs, the power is fine and everything is normal. Its not consistently missing, just sometimes, and when it isn't it functions normally, no smoke or stalling. Could the CPS be a possible culprit for something like this or would that just be too easy?

 

[BillGotthelf]

It definatly sounds like the VP44. It should still be under the 5/100,000 mile warranty. GOOD LUCK.

 

[Amianthus]

At first I thought mine was the APPS, until I hooked up my laptop to it while I drove around. I found out that the APPS was funtioning just like it should, but the pump was still not acting right (lack of power and no reaction indicated on the FMS from my throttle input). Next I thought it might be the CPS. But the RPM indicated on my laptop was stable and correlated to the FMS reading and the tachometer. So that left me with one other option. The VP44 was going bad. Any other behavior should've resulted in a code of some sort. But none were found. That and it's been getting progressively worse and it's misfiring more and more. It started as an intermittent problem also, but has gotten much worse in the last week.



I contacted my dealer on this (I knew what the answer was gonna be). And he agreed that it's a good chance it's the VP. But I'm on my own for repair of it because I've slightly modded my rig. I know, I know. Shame on me for trying to get DC to fix it, but for $1k, I had to try.



My advice is get to someone with a laptop with some diagnostic software on it and start checking things out. Yes the CPS could do that, but you should see the tach acting funny and you would probably have a code set. Or take it to a good Cummins shop. Then you'll know for sure. Good luck with your pump situation.

 

[shawn huizenga]

I was tinkering around with the pickup today and found what I believe to be the problem. I might back up about three steps here in my description of having good fuel pressure. This was assumed, because I had the in cab fuel pressure gauge hooked up until about 250 miles ago when the fitting on the gauge started leaking. At that point it had good fuel pressure, about 14 pounds at idle and 12 going down the road. I just assumed that three days later the pump would be producing similar pressures. But just to rule it out I decided to bump the starter and the lift pump didn't give a peep. I reached under there and wiggled the wiring harnesss going to the pump and it started pumping normally. Then I thought maybe that was the problem so I took off the adapter harness going to the lift pump and cleaned it and checked for breaks in the wire, couldn't find any, applied some dielectric grease to the connections. The pump has been functioning normally since then. Pickup fired up and has been running fine since then. I've put about 75 miles on so far today and the engine hasn't missed a beat. Is it possible for the lift pump starving the vp for fuel to make it act the way it did? Hopefully so, because it seems to be running good since the connection was cleaned and reconnected. I realize the effects of starving the vp for fuel and am prepared to bite the bullet and purchase another if that is the problem. I have decided not to bother with warranty, because of the damaged pump solenoid wire my pump somehow got! Anyhow, thank you for your help and I hope that's all the problem was.



Shawn Huizenga

 

[Shovelhead]

Glad to hear it's good news, (and a cheap fix)



You now have learned troubleshooting rule #1.



Never A$$ume anything.



Ed

 

[Amianthus]

That is good to hear. And it's a good example of how important a fuel gauge is.

You should now be able to breathe a sigh of relief. At least for now.