truck loping hard when i pull it in drive and will shut off,

qssc

qssc

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Sep 22, 2008
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i am posting this in here because im almost positive its something to do with the p pump system. i recently p pumped my 98 24v. I took off from a stop sign earlier today and it had a weird random like sputter iv never felt. i let off instantly and give it gas again and it as fine. i said ok weird....i kept driving and when i come to a stop, the truck started loping real hard. put it in neutral and it would idle ok on its own, drop in drive or reverse and it loped so hard it shut off. if it gets over 1200 rpms its super smooth and runs fine. i have been driving the truck daily for about a week with no problems.

THings iv checked:
i checked fuel pressure. getting a reading of around 50psi from my fass pump (only has a 40psi spring in it)
i changed fuel filter and no help.
the overflow valve was new when i p pumped it and started driving it last week..
if i pinch the return line off, it will clear up in idle and run smooth and kinda want to act right in drive with foot on brake but still jumpy (fuel pressure will raise up)
i backed the Gov springs back 2 clicks and that didnt help.

the pump was just benched a few weeks ago before i put it on and like i said iv been driving it for a week and its been running awesome with no issues. any help is appreciated!
 
qssc said:
i am posting this in here because im almost positive its something to do with the p pump system. i recently p pumped my 98 24v. I took off from a stop sign earlier today and it had a weird random like sputter iv never felt. i let off instantly and give it gas again and it as fine. i said ok weird....i kept driving and when i come to a stop, the truck started loping real hard. put it in neutral and it would idle ok on its own, drop in drive or reverse and it loped so hard it shut off. if it gets over 1200 rpms its super smooth and runs fine. i have been driving the truck daily for about a week with no problems.

THings iv checked:
i checked fuel pressure. getting a reading of around 50psi from my fass pump (only has a 40psi spring in it)
i changed fuel filter and no help.
the overflow valve was new when i p pumped it and started driving it last week..
if i pinch the return line off, it will clear up in idle and run smooth and kinda want to act right in drive with foot on brake but still jumpy (fuel pressure will raise up)
i backed the Gov springs back 2 clicks and that didnt help.

the pump was just benched a few weeks ago before i put it on and like i said iv been driving it for a week and its been running awesome with no issues. any help is appreciated!
Click to expand...

I would say you have a governor spring problem.
 
I don't understand why it's ran fine all week?

I was think maybe I got a bad overflow valve
 
measure fuel pressure right before the pump, that will tell you if the ofv is bad or not. If fuel pressure is ok, then i would check all your injection lines. If one loosens up a little it can cause an issue like this. Check the basics first...
 
if i pinch the return line off, it will clear up in idle and run smooth and kinda want to act right in drive with foot on brake but still jumpy (fuel pressure will raise up)


Check you fuel psi with a diff gauge.. Sounds like the fuel psi is low
 
Can a overflow valve stick open causing it to dump too much fuel off?
 
I almost think that's the problem I pulled the return line off and started the truck and it BLOWS fuel everywhere. Don't think FP is too low. Brand new gauge I'm using to check fuel psi at well. It's ashame if it is overflow as it was brand new and haven't put but maybe 500 miles on the truck
 
I'll try it tomorrow morning when I go back to the shop. It is a stock one, and I got new o rings today so I can pull the barrels out and put new o rings on them to get rid of the leaks coming out of the top of the pump

How far should I stretch it ?
 
i tried stretching it with no help. here is a video with the pump running and the overflow valve is whining. anyone else do this?

EDIT:guess you have to click the word lope for it to play at the top



[ame="http://s50.photobucket.com/albums/f346/mdmigr8r/?action=view&current=lope.mp4"]lope.mp4 video by mdmigr8r - Photobucket[/ame]
 
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You should be able to hear fuel bypassing the OFV with the lift pump running. What does it idle at? How many rpms does it drop when you put it in gear?
 
its a suncoast triple disc it fairly tight in my opinion. idle is set at 950 and drops to about 650 when droped in gear. Im just not sure what the popping was the time i took off. ever since it did that pop it hasnt been right since. tried backing off 2 clicks on Gov springs and still did not help.
 
Truck is losing its prime I think. Not hard cranking just cranks a little longer than usual. I just got done checking timing, and it was dead on 24* timing where I had it set. Also in between changing connector tube o rings, dv holder o rings, and barrel o rings. I just milled the plate out to keep barrels aligned so I can pull 1 up at a time.

But, I have to take a break and go to the farm because there's a problem so I'll be back to working on it later
 
i didnt get the barrel o rings in but did put new dv o rings in and then connector tube o rings, and i started it to check for leaks and shut it off, went to start it a few minutes later and it has a horrible miss. i know all the DV springs were seated correctly. it has a consistant miss, and the exhaust has a sharp crack noise. im going to crack injector lines tomorrow to see what cyl has an issue and then switch dv's around to see if the stays or miss follows to other cylinder. if it stays then guess im looking into an injector tip blowing
 
Every time that cylinder fires there is a large puff of black smoke
 
I have a VP44 pumped 24valve, I changed my injectors a little over a 2 months ago and after I did it my truck did the exact same thing. Loped horrible under idle and slow speed to the point where if I tapped the throttle it would stall. After about two or three weeks tho it cleared up, I don't know if the injectors had air trapped in them, but it had to be an injector issue which makes me think yours is as well.
 
Pull your injectors and see if they are covered with carbon or you may have one stuck open and its over fueling. My truck did the same thing and my tips were covered in it and I may of had one stuck open but they were also stock with 223,000 miles. I already had bigger injectors I was going to put in it and after we got them in it ran fine.
 
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