No codes so i imagine it's fuel related. The PO said he changed the fuel pump and several parts. I changed anything code related and got it running nice but when you drive it it drives okay for like 1 min then falls on it's face. Also A loud bang comes from the driver side fender area sounds like a backfire... My buddy hooked it up to a OBD1 sensor and we drove it around. everythign checked out except the fuel/air mix went up and down between rich and lean... At idle we are getting good fuel pressure and we are stumped any ideas before I go and waste tons of money on overrated sensors... (daily driver is a 73 Beetle, not a single sensor therefore the $40 here and there doesn't happen.)

 

I am dealing with a similar issue on my 91 full size Blazer. If you ever fix the problem, please let me know.

 

Not to be smart....but I assume your are referring to the CPFI system.
In 94-95 GM did produce a W with a TBFI system.
I have one.
Please give more specifics and I am sure someone will be able to help.

 

You know what causes classic symptoms of falling on face - enigne just cuts out completely- at certain rate of accleration/throttle angle/load ? Bad coil, that's what.

On my 57 chevy, my 69 beetle, my 84 Mustang svo.
And no, you proabbly wont see it in the dark, it's internal.

 

Yeah it isn;t the TBI one. I know it isn;t the icm, tps, catyltic converter. etc I don't smell gas or anything. Just falls on face at open throttle

 

As Pettyfog said it could possibly be the coil.
You can check for the spark and color of spark to get a general idea.
Personally I would lean toward the ignition module in the distributor or timing.
Just a few months ago I had a problem similar happen on my 91.
Turns out it was the number 1 wire loose on the distributor.
Check for loose wires,don't tear everything apart at once.
Try things systematically and keep a record of things tried and failed.
It'll pay off later.
Check for codes.I have pulled codes when the service engine light wasn't
on.
Don't freak,you'll get it fixed.

 

Hobowatson,
I would change the fuel filter (located under driver side along frame rail) A partly clogged filter will cause the fuel starvation problem you seem to have.
Good luck...
94 LT since 1995

 

jimbo1994 may have a point there.
When you said the previous owner installed a new pump I figured they must have checked the pressure afterwards.Only makes since.
You should check just to be safe.The pressure should be around 58-62 psi,depending on your gauge.
You could have a leak under you plenum.Drivers side is usually where it starts.
Check your oil to make sure no fuel drain into your crankcase.

 

OK i had a 93 jimmy that did this same thing would atart and run but would fall on face under accelration. All o this started after I changed fuel pump. I out new spyder, fuel lines from intake to spyder, cap rotor plugs, wires, and still did the same. So being that it all started after I changed the pump I dropped the tank again. with the pump out enough to still get gas but where I could see in the tank I had a buddy hit the key and sure enough one of the clamps on the hose from pump to accending unit wasen't tight enough and was apraying gas back in the tank but still pushing enough through to start the truck. Sounds like that could be the problem with ours as well being the PO changedthe pump and now there is this problem. Hope it helps

 

Is it RPM related at all or can it rev up freely in nuetral? If it stops at a certian rpm range the cat could be clogged.