Truck problem (help diagnose)

[Coreshot]

OK, my '94 GMC has began having issues, and I need some RME opinions to help me diagnose it before I spend money I don't have to get itt fixed. Here's the deal...

The truck has started stumbling intermittently, usually upon mild acceleration or staying at a constant 2500-3000 rpm. It doesn't do it every time, but it is getting worse the more I drive it. I can sit in the driveway and rev it up and even hold it at 3000 rpm and it won't do it, it's only when I'm driving it. I can putt around the neighborhood @20mph, and everything's fine, but as soon as I get on the main road and and push it up towards 40mph or so it starts stumbling. It's intermittent, so I don't think it's a spark issue. The truck actually died on me last week, and I had to coast into a parking lot to get off the road. Then, the truck would fire right up and immediately die. I know it sounds like a fuel issue, but I have replaced the fuel filter and even dropped the tank to swap out the in-tank fuel pump. Neither of them fixed the issue.

You got anything? 1994 GMC, 350, 4L60E.

 

[I Lean]

It sounds like when the fuel pump died on my '89 POS Chebby. I know you said you swapped it already, but.....

 

[74highboy]

my mom had the same problem when the cat melted on a road trip

 

[Meat_]

Did you use a Delco pump?

 

[Coreshot]

Did you use a Delco pump?

NAPA Delphi pump.

 

[LT.]

I to sound so ignorant but, have you thought about changing the fuel filter? I had a fuel filter that was bad. Changed it and the problem still persisted. I ended up changing it again and come to find out there was some debris in the fuel line. After a few minutes of just letting the fuel pump move some fuel all the debris finally were pumped out.

LT.

 

[Coreshot]

I to sound so ignorant but, have you thought about changing the fuel filter? I had a fuel filter that was bad. Changed it and the problem still persisted. I ended up changing it again and come to find out there was some debris in the fuel line. After a few minutes of just letting the fuel pump move some fuel all the debris finally were pumped out.

LT.

I have swapped both the filter and the pump, but I also thought about debris in the lines. Maybe I'll check this possibility tomorrow.

 

[Greg]

Plug wires shorting out? How old are they?

 

[Turtle]

replaced them last summer, maybe 3k miles ago. The only problem I have with this theory is the fact that it isn't a consistent problem.

Edit; This is coreshot by the way.

 

[Coreshot]

my mom had the same problem when the cat melted on a road trip

I've actually had this suggested already, but haven't checked it out.

 

[lewis]

Had the exact same issue on a 98. I replaced the fuel pump and egr valve lots of other sensors and never came to any conclusion. I took it to tunex and they had it for awhile and cleaned out the injectors trying all sorts of stuff. They finally came to the conclusion that all my injectors needed to be replaced. I sold it the next day for cheap cause I was sick of messing with it.

 

[74highboy]

i used to work at the kearns tunex i know people have had problems with tunex but the owner of this one is the kind of guy that wont sleep till he figures it out id take it to him if you dont want to mess with it any more i know you dont want to spend much but for the diag fee i think it would be worth it when i worked their it was only 54.95 it might have gone up but i dont know