1995 Blazer with 4.3 4wd, auto. It is obdII, start it up it idles fine, drive it around giving it about 1/3 throttle it does fine no issues of missing or chugging or anything. If you really stomp on it it just sputters and sputters, chugs ect and the tach jumps up and down, initial impression is maybe getting too much fuel because it does not backfire. Anytime your foot is really in it hard rather parked or not it does that, although when driving it is much worse. It is not throwing any codes what soever and computer was recently replaced. Any ideas?

 

How many miles on the fuel filter?

 

I'm not sure, just bought the car. That was one of my first suspicions also.

I actually had a new filter in the garage and I just swapped it, and it appears to be doing the same thing, so I really don't thinks its fuel filter.

 

Just throwing out some ideas, but possibly a catalytic converter getting plugged up?

 

I thought that the cat was a good possibility, but alas it wasn't. It looks like someone had gutted part of the cat already but I finished it off but it still does the same thing. SO its not the cat and not the fuel filter. The truck runs perfect at low throttle no hesitations, no misfires, no backfires. But if you rev it pretty hard it starts chugging above about 3 grand. While driving if you're going 30 or so and try to get up to speed laying heavy into the throttle will result in that same chugging and the tranny will not kick down. But if you are below about 1/3 throttle it runs fine.

As an update: I checked fuel pressure, at start up it is about 55 and when flooring it to get it to sputter it stays a constant 62 psi

 

my 95 is doing the same thing to the t funny my cat was gutted as well i just put a post up about it take a look at mine so ya get an idea about what not to buy or bother with yet i have drove my self crazy to try and figure it out i gone through so much with it i'm now down to the last couple sensor and a pressure regulator kawiaaron910 i'm not so hot with the computer so i can fighre how to make a link to my post just search it love the truck hate the fuel system

 

No need to do that. We can see the thread you created and, once again, please use punctuation when you post.

 

WOW -- my 2000 is doing exactly that also-- I am thinking maybe throttle position sensor ?? Just bought the truck Friday, and haven't had time to check it over yet---
My fuel filter doesn't look like its ever been changed, and the nuts look rounded(vise grips??) so I bought a new fuel line yesterday ($85)--and was gonns do the filter first--maybe I should try the TPS first ( only $35 ). Truck has 203,000 miles--runs like a top though--got it CHEAP !!!

Gary

 

Just food for thought but when you guys checked the cat did you also check the muffler? If the cat partially gutted itself the stuff has to go somewhere. The muffler is next in line.

 

Just replaced the TPS -- no obvious help there--Darn !!!

I am gonne drop the exhaust next and run it open -- see if that makes any difference -----

Gary