1995 S10 Blazer Stumbling

[slammed79]

I thought I'd post this question here to see what others thought as well. My room-mate's 95 S10 Blazer with a 4.3 fuely engine  picked up a wierd stumble on sunday that has gotten progressivly worse since.

When accelerating normally (i.e. not driving like an idiot) the engine will stumble at 1400-1500 rpms. It will also do this when you're light on the throttle keeping with traffic.

The check engine light is not on, and the truck has an obd2 plug on it. I thought GM switched in 96?

I'm kind of thinking throtle positioning sensor, but I'd like some other input.

Anybody>

[bake74]

     My first though would be the throttle positioning sensor also, but if you hook it up to a scan tool there might be codes, even if the check engine light is not on.

[slammed79]

Thanks Bake. I just gotta find somewhere with an OBD1 scanner. Apparently the Orielly by the house doesn't have the software loaded into their scanner.

[slammed79]

Well, we got the truck hooked into a friends Genesis, and it threw no codes. But it is leaning out right at that stumble point and then going rich right after. The only idea my buddy with the genesis could come up with is the egr going bad. He has one at his shop we're gonna toss on and see what happens.

[Captkaos]

Is it the Vortec with the spider injector?

[slammed79]

Is that the mfi? I'm very inexperienced with efi systems.

[Captkaos]

It is the setup that has tubes on it. looks like a spider, they notoriously had issues.

[bake74]

It is the setup that has tubes on it. looks like a spider, they notoriously had issues.

     You can not mistake what Capt. is talking about, it looks like a nightmare to work on.

[slammed79]

Yeah its spider injection. My roomie decided to throw a hail mary and we popped a new fuel pump in it yesterday. Didn't fix the issue. So we're taking it to a "real mechanic" today for a diagnosis. All that's left to fix fuel system wise is the spider. Since they are a couple hundred from Oreilly he needs to be darned sure that's the issue.

The genesis said it was leaning out right at that stumble. Is there a fuel pressure regulator on that thing or is it tied into the spider? I'm done beating my head against a wall with it. And I want my truck back lol