chevy stalls during acceleration

Has the check engine light come on? Also, have you checked to make sure the catylatic converter isn't plugging? If all of these things are fine, have you checked fuel pump pressure?

.no check engine light or stored codes,converter is new, and like I said..f.p. is 45psi....I wanted to know if when this engine is in open loop could the throttle position sensor , if it was real worn..shut the engine down as I described??

I would have to say no. It would cause idle problems or maybe surging, but I can't see it shutting it down.

well??????????????????????????//

Does he ehicle have the 3.1L V6? If so, I would check for an intake vacuum leak. They are common on this engine.

yes, like I said..3.1.intake vacuum is 17...gm had trouble with intake gaskets when they put dexcool in the engines...it rotted stuff...this engine doesn't use..it's a 1991.....

Honestly, this is a tough one. If the TPS is bad, I would say it wouldn't shut it down, but I'm at a loss.

I expected a little more than this for an answer....how long have you been a mechanic??

is anyone going to answer my question I donated for?

[b:e94f81f872]response deemed inappropriate by buddycraigg[/b:e94f81f872]

Sir:
I have been a mechanic for 29 years. Everything you have described to me indicates there is a vacuum leak or a shortage of fuel to the engine. I will repost this so others can answer it.

To answer some of the side questions you asked.
Yes, the computer is still using the TPS and the MAP while in open loop.
The ECM is just using a predefined table for fuel delivery and spark timing.
After it goes in to closed loop, then the ECM gets to make it own adjustments.

Your fuel pressure is at 45, but what does it do when it's running?
It should be down to about 37 at idle, and then when you blip the throttle open quickly, it should jump up to 42-ish.
If you dont have these numbers, then the pump isn't able to supply enough volume, or there is a restriction in the fuel lines.

You can check the TPS, you have 3 pins in the connector.
resistance between 1 and 2 will be high and should go down smoothly as you open the throttle.
pins 2 and 3 should have low resistance and go up smoothly as you open the throttle.
If the resistance fails to change, or jumps around then you have a problem.

finally, check for a weak spark.
I've seen failing ignition modules that don't ground the coils enough for them to get a full charge, so when the magnetic field collapses, there's not enough to make the plugs have a good hot spark.
And thus the spark is not enough to ignite a rich fuel mixture.

Hopefully one of these suggestions will lead you to your problem.

one more thing. as an added test to see if you are starving for fuel. unplug this line and spray starting fluid in the hole in the big rubber tube while opening up the throttle.

thanks for the professional answer...really appreciate it...fuel pressure was checked while the car was running, and it was as you described..also kept good pressure after it stalled...I will check tps sensor and do spray test anywys..it sure seems like it is an electrical thing...it doesn't stumble...just a real fast quit..will reply soon...thanks again

hi Buddy...well, I re-checked the fuel pressure with it running and it was as you said it should be..it even has good pressure in the rail after it stalls..I cleaned the iac valve and the throttle plate..it wasn't really dirty, I had cleaned it 6 mos ago when I changed the air filter, but I did notice quite a bit of oil in the air pipe for the air cleaner..the engine is good, so I'm gonna change the pcv valve..one thing..I had a digital olm meter hooked up to the tps..I didn't get any flat spots while checking , but it sure jumped around alot..like started at 1.4 then jump to 1.8 then go down to 1.5 then 2.0 etc...and then sometimes it was a pretty smooth , gradual transition...I'd say 3 out of 4 times it jumped alot..2 of us checked it several times..should I change it?..thanks

I had to move the engine forward and take the map sensor bracket out just to get to the pcv valve in the back valve cover..it has a hose that goes under the plenum...do I replace the whole thing...what an idiot place to put that

[quote:32224502cc="albinasboy"]I had a digital olm meter hooked up to the tps..I didn't get any flat spots while checking , but it sure jumped around alot..like started at 1.4 then jump to 1.8 then go down to 1.5 then 2.0 etc...and then sometimes it was a pretty smooth , gradual transition...I'd say 3 out of 4 times it jumped alot..2 of us checked it several times..should I change it?..thanks[/quote:32224502cc]
If you are sure you had a good connection on the terminals when it was jumping around, then yes i recommend that you replace it.
Although I will be surprised if it is the root cause of your problem.

hi...well, I haven't put the new tps in yet...I re-learned the computer...then after while it was idling, it stalled..I had a fuel pressure gauge on it and it said 40 psi...it re-started and I noticed when I rev it up, the pressure gauge will bounce up to 45psi just for a sec...then go back down...then it stalls...is it normal for the fuel pressure to bounce up like that?I also tried spraying in starting fluid while revving..it just stalls

.I have a "known" good module and coils ...should I put those on?

one more thing...after it stalls..it has 40 psi f.p..but if it sits for a min it looses pressure...it's not leaking ..maybe just my gauge...also after letting it idle for 10 min,,and it's still running..the vacuum gauge dropped from 20 to 14...gauge says "late ignition timing"...it always runs rougher at idle when hot

[quote:4196e74dcb="albinasboy"]is it normal for the fuel pressure to bounce up like that?[/quote:4196e74dcb]Yes, the pressure regulator responds to vacuum.
When you open the throttle quickly, the intake manifold vacuum drops and the pressure regulator closes off the return fuel line. So there is more gas being sprayed out of the injectors because of the higher fuel pressure.

[quote:4196e74dcb="albinasboy"].I have a "known" good module and coils ...should I put those on?[/quote:4196e74dcb]Yes.
Until we can find a cause, we are just guessing.
But my instincts are telling me that it's a spark problem.

hi...I put the new tps in, since I already had it, and it runs smooth and hasn't stalled...I can rev it up with no problem...thing is...it idles high? ..maybe I put in wrong?funny, I took it out and put the old one back in and it idled right down..I checked the part no and it was the right one..when I unplug the new one the idle is still high..I doubt if it's even getting a signal..lol..autozone,ya kno..lol

it sounds like the ignition modual under the coil packs when it heats up it shuts down

it shuts down when it's cold too!...{per conversation earlier).I'll get it back in the garage and go through it tomorrow.........

hi..back to the lumina..ok..It started right up ..drove well for awhile..then when accelerating it stalls at 35 mph...it re-started several times but would continue to stall at around 35..brought home ,let sit,,wouldn't start..put remote starter on and attached fuel gage to rail..42 psi..relieved pressure and cranked..went right back up..took front 3 plug wires off..and has a good sparkl..good fuel and spark,,but no spark..in last 2 mos have replaced wires,plugs,cps(G.M.), fuel filter and o2 sensor..computer maybe? how to check for power ay injecteors? thanks...wpold like to get this fixed...need a scanner

[quote:7e712102b6="albinasboy"].took front 3 plug wires off..and has a good sparkl..good fuel and spark,,but no spark..[/quote:7e712102b6]
you just contradicted yourself.