OK so I have a 2000 blazer 4.3 automatic 4x4 and this thing has gotten me clueless now. My problem is when you first crank the engine up to drive everything idles fine but when you put it in gear and start driving it acts like your hitting rev limiter while it's trying to shift between 1st and 2nd, then the same between 2nd and 3rd. So I thought it was the tranny until I got curious and put it in park and reved the engine and at higher rpm maybe between 3000 and 5000 it starts stumbling like it's running out of gas. My fuel pump checks out good, brand new fuel filter, plugs, plug wires, cap and rotor. NO CLUE WHAT THE PROBLEM IS CAN SOMEONE HELP ME BEFORE I RUN THIS THING OFF A CLIFF?????? P.S. No engine codes present on scanner if this helps.

 

Test the fuel pressure. Specifically when you are experiencing the problem.

 

Looks like you taken care of the common problems, providing fuel pressure checks out. Something that may seem very obvious but often overlooked is the air filter. Sounds like your engine is getting starved of either fuel or air. If the air filter is good, make sure the MAF is clean. Might also be time to check out the fuel injectors. Run some cleaner through the tank a few times and see if that helps out.

EDIT: Can't believe I forgot to mention the cat. Somewhat common for them to get plugged up and what you are describing is the exact symptom of the cat starting to get clogged.

 

Yep, if fuel checks out, the next thing I would do is check the air filter. If that checks out, pop off one of the upstream O2 sensors and drive it. If you still experience the bog, with the O2 sensor removed, then your cat is not the problem. If it is cured, then your cat is restricted and needs to be replaced.

 

Double check your plug wires and make sure they are securely connected.

 

I dont know if this helps or not but this is the recent update checked the plug wires they are good, air filter is good, fuel pressure is good, I have not tried pulling the o2 sensors yet but here is another bit of info when it's cold outside 50-70 degrees it will stumble and studder but if it's 75-80 degree's it won't do it at all. ???? maybe this will help a little more. Oh the CAT. was replaced a month ago.

 

well I guess not

 

So... Impatient much?

Just because the cat is new does not mean that it still is not contributing to your problem.

What, specifically, is the fuel pressure? What is it at the specific operating conditions when you experience the problem?

And instead of being critical of us for not responding promptly to your post, maybe you should try following the direction we give you and reporting back. You could always pay for someone to fix your vehicle.

 

NO not inpatient just frustrated and I have done everything everyone has mentioned except pulling the o2 sensors out. The full pressure is between 60-64 p.s.i. from idle to wide open. The only time it does this problem is from start up to the first 5-10 miles it's driven then it doesn't do it any more for the day until the engine cools back down. I apologise for the short patients with everyone but this thing is makeing me so mad because it's probably something so simple.