'96 Sierra 4.3 unusual acceleration problem ... should I pass on it?

[jnewkirk77]

So I found a solid, one-owner '96 Sierra C1500 with the 4.3 and 4L60-E, and went to check it out yesterday. The truck has 225K on it but has obviously been pretty well maintained. It's an ECSB, which would be a nice addition for when I need to take the kids to school and the wife has the van.

It has a very odd issue, though: When I took off with it, as long as I stayed at half-throttle or less, it ran great. No issues at all. But as soon as I floored it, it was like hitting a wall. No acceleration, no downshifting, just sputtering.

The dealer told me he'd just gotten it out of the shop, where they did a tune-up including cap and rotor. I did note (and he did, too) that it has a loud fuel pump. Wondering if that might be the problem.

I'd like to think if it's a simple fix (sensor related or even fuel pump), I might still be interested in the truck. But if we're talking a transmission issue or something larger, I don't want that kind of headache.

Any thoughts???

 

[DerekTheGreat]

Unless you know what to look for and know what you're doing, it's never a simple [cheap] fix haha..

 

[jnewkirk77]

Unless you know what to look for and know what you're doing, it's never a simple [cheap] fix haha..

Oh, that much I know! LOL

 

[Schurkey]

There's plenty of things it could be. The first three that come to mind are:
Low fuel pressure/volume
Restricted exhaust
TPS failure

Check fuel pressure WHILE THE ENGINE IS ACTING UP, put a scan tool on the thing, and look at the data stream.

 

[jnewkirk77]

There's plenty of things it could be. The first three that come to mind are:
Low fuel pressure/volume
Restricted exhaust
TPS failure

Check fuel pressure WHILE THE ENGINE IS ACTING UP, put a scan tool on the thing, and look at the data stream.

Thanks! The dealer is having it checked out again today. Hopefully his mechanic will figure it out; if not, well, there are other trucks out there.

 

[RI Chevy guy]

So I found a solid, one-owner '96 Sierra C1500 with the 4.3 and 4L60-E, and went to check it out yesterday. The truck has 225K on it but has obviously been pretty well maintained. It's an ECSB, which would be a nice addition for when I need to take the kids to school and the wife has the van.

It has a very odd issue, though: When I took off with it, as long as I stayed at half-throttle or less, it ran great. No issues at all. But as soon as I floored it, it was like hitting a wall. No acceleration, no downshifting, just sputtering.

The dealer told me he'd just gotten it out of the shop, where they did a tune-up including cap and rotor. I did note (and he did, too) that it has a loud fuel pump. Wondering if that might be the problem.

I'd like to think if it's a simple fix (sensor related or even fuel pump), I might still be interested in the truck. But if we're talking a transmission issue or something larger, I don't want that kind of headache.

Any thoughts???

Clogged fuel filter, pump probably working to overcome it. Swap the filter, probably smooth right out

 

[HotWheelsBurban]

Throttle position sensor might be going bad. If it looks like the original one, it's probably toast. They're not intended to last for 25 years, and I know on my 99 5.7 vortec (which the 4.3 is 3/4 of) the part cost under $50 at my local parts store. Online they're probably cheaper. There's so many sensors and other electronic stuff on these trucks that can act up and make the truck go crazy, that's the only thing I don't care for on them.

 

[Bondovw]

Maybe a clogged cat ?

 

[Schurkey]

Clogged fuel filter, pump probably working to overcome it. Swap the filter, probably smooth right out

Throttle position sensor might be going bad.

Maybe a clogged cat ?

Doesn't matter. Not his problem.

The dealer is having it checked out again today. Hopefully his mechanic will figure it out; if not, well, there are other trucks out there.

 

[jnewkirk77]

Ended up passing on the truck. I didn't really get a straight answer from the dealer when I checked back, so ... I'm not gonna get myself into headaches when I don't need to.

THANK YOU to all who offered ideas. Much appreciated as always!