Engine/Transmission (1994 - 1998) Help trying to fix dieing truck

[mikel]

Hey gang, I'm hoping someone here has run into this before.



I'm trying to help a neighbor fix his truck, it is a '96 5-speed w/ 370's and a "fuel plate". He's not sure which one.



The problem is that it will die out sometimes (but not all the time) after being run hard. If we drive it 'normal' then it's fine, but a good hard blast in any gear and when you take your foot off the throttle the engine wants to die instead of idling. If you keep it going with the throttle then eventually it'll decide to catch on and run on it's own, but if you take your foot off the throttle it will die.



The truck has a full fuel tank and less than 100 miles on a new fuel filter.



I'm going to take my fuel pressure gauge over there tonight and check that, I'm hoping it's something like the overflow valve or lift pump.



It starts good and seems to be making good power...



Anyone run into something like this before?



Thanks,

Mike

 

[Joe G.]

It sounds to me like the idle is too low.

 

[mikel]

Thanks for the idea, but unfortunately the idle is at almost 1000 rpm right now. We did that in an attempt to correct this problem, but it didn't work.



It idles fine 99% of the time, it's just that every once in a while only after a hard run it'll want to die.



Please keep the ideas coming.



Mike

 

[CFAR]

Maybe its sucking air on a hard run, then it takes a while to get the air out?

 

[krs]

It's gotta' be running out of fuel for a little while so you might well fix it with an overflow valve. Otherwise I'd go looking for a flow test of the liftpump. I started wondering whether a too small set of delivery valves could do that but think it's more likely to be pressure or flow - OF valve or pump.

 

[mikel]

Quick Update:



He's got a new lift pump and overflow valve coming. We're going to replace both of these when the new parts get here and I'll let everyone know how it works out.



Thanks,

Mike

 

[Andy Redmond]

Mike:



I have a customer w/ a 98 12v. that did this intermittantly.



He has me change parts at certain mileages "just because. " The lift pump he insisted that we install seemed to stop the concern.



Maybe the check valves were fritzing out?



He later had me install the 3k gsk. The retainer nuts were barely on a click. This would cause it to die sometimes? When sudden acceleration occurred to make a turn in traffic, across a divided highway etc.



You might check for a loose fuel heater and the prefilter bowl for air entrance.



Good luck

Andy

 

[Extreme1]

Check the heater filter for blockage.