95ls 4x4. 118xxx miles. started hesitating like with bad gas. ok, added heet, changed fuel filter.
Ran out gas. filled up with 93 octane.
upon acceleration, no inital hesitation. Mash it to the floor, spudders, carries on, not sure.

replaced cap, rotor, plugs, alternator(was bad)and spider(pressure regulator went out on spider)
replaced feed and return lines while under intake.
new starter.
new pcv.
OK. started her up, smooth! pull out, no problem. as soon as it is under load, (put the hammer down,) it spudders like it's choking or not getting something.

only thing I haven't replaced since july is the ECM and the Coil! everything from the tank up is Brand new.

I am lost, can anybody bounce a fresh idea my way?

Greatly appreciated.

great site here by the way, glad to be onboard!

 

O2 sensor? That's what was wrong with my 98, I had a bad O2 sensor, that was then replaced with another bad one (stupid manufacturing defects) but once I had a good sensor in there all was smooth.

 

come to think of it, i didn't replace the o2 sensor(s). any way to test that theory by by-passing them? i know they are pretty expensive and have dumped alot of money here this week. is there some test to see if the sensors are working or faulty?

thanks!

 

Off the top of my head, no I cannot. Yeah sensors are expensive, about $65 a pop for the ones for the 98. But seeing how there are a lot of differences between your year and mine I can't think of anything you could do. On mine I could take the post cat sensor and put it in place of the others ones. Not sure if you have that option or not.

 

i will try that, they are listed as the same for up & downstream sensors. I will check in the morning and see if I can swap them. thanks alot.

 

No problem, I just remember how much trouble I went through when I had that problem, and how much money was spent on something so simple (new plugs wires, cap, rotor, fuel filter, spider assembly, etc) and $1800 later it was just an O2 sensor causing the problem.

 

While the rear most o2 sensor is out drive it and see if your issue is better. It'll be loud, you won't have to go far but if it is better, I'd suspect the catalytic convertor. Good luck, keep us posted! Merry Christmas

 

The rear most O2 sensor is the downstream sensor and will have zero affect if it is a catalytic converter problem as it is behind the catalytic converter. You want to vent the pressure that is building up from a restricted catalytic converter by opening up the exhaust somewhere between the engine and the cat.

With any potential O2 sensor problem, you can just unplug the suspected O2 sensor electical connection, and drive it. This will push the PCM into a preset fuel curve based off of sensor readings from the other sensors.

But I do suspect a catalytic converter problem. As such, you should remove the O2 sensor that is located between the catalytic converter and the engine. Drive it like this and see if the problem is corrected. It is possible that the fuel leak from the bad FPR has plugged up the catalytic converter.

How does the truck rev when in park or neutral?

 

swartlkk-after figuring how to register to the site and then how to respond to the original poster, I had a brain f*%@! Of course pulling the rear most o2 sensor would do nothing. Thanks for noticing! Yes, pull the o2 sensor in front(engine side) of the convertor! Just wanted to mention that as have put many convertors on many Blazers and 1995 was a 'problem'-frequent year! JP

 

Any of the CPI motors with failed or failing FPRs can cause a catalytic converter to fail. Fuel contamination will plug a cat quite fast.

And no problem on catching that. That's what we're all here for!