I have a 1992 V6 Pontiac Firebird MPFI 3.1

It ran fine for a while but then out of nowhere it just decided it was going to run very sluggish, barely idling and would eventually die. It used to be that when I would start the car up and put it into nuetral it would fire up and run slightly better, but as soon as I hit the gas pedal it would immediately go way down in RPMs and them would start to quickily climb back up.

That worked enough for me to get the car home, but when I would try to drive it around the block the only real way I could get the car to really move was to throw it into reverse and that seemed to get the car rolling again (although it would still bounce around on the RPMs.

Now, fast foward to 3 months later (it sat all winter) I can get the car started, it idles fine but as soon as I hit the gas pedal the car dies. It still has the full tank of gas I had when it originally started this problem but the day it happened the gas was only about a day old and was working great the day before. It was 97 octane so I doubt the gas was any of the problem with the car.

I was going to do a TomP tuneup on it but I didn't want to do that until after I have found out what the problem is. I would hate to do the full tuneup only to find that the problem would somehow burnout my new sparkplugs.

I do plan on putting a new fuel filter in tommorow and checking to see if I get a code readout, but does anyone else have any suggestions? The Fuel pump does prime, but I am unsure of what pressure it gets until I have a chance to check it tomorrow.

Thanks,

Brad

 

Buy some el-cheapo spark plugs and do the TomP tuneup. Then after you find and fix the problem, you can get some of your good plugs in there and drive happily ever after.

 

2 words
Fuel Pump
It's in tank
My call is that's the problem.
When ya check the pressure you'll confirm my suspicion.
I'd buy a fuel pump pressure gauge before ya waste time with any other idea.
That's my suggestion.
Good luck.
Once fuel pump is replaced, your car will fly again! and milage will increase, too.

 

same to me 2 years ago
it was the ECM

Horst

 

Well on Saturday I went and completed the TomP tuneup. Nothing worked, changed out the fuel filter, air filter, oil filter, transmission filter, checked and replenished all fluids (changed oil and flushed the radiator), changed the O2 sensor, the PCV Valve, spark plugs, wires, Cap/Rotor.

I checked the gas pressure and the guage read 45psi.

So I guess I can look at the ECM. Any other suggestions?

If I don't find it soon I may just take it into the dealer, but at least I know I have all of the other stuff taken care, most of which I needed to do sooner rather than later anyway. Thanks for the suggestions, I have seen this problem on other threads, but it all seems to be fuel pump related, mine isnt.

Brad

 

codes?
Injectors?

 

I did all the changes you did

finally the ECM and bingo

Horst

 

I say fuel filter

 

Atleast ya eliminated one possible area of concern.
When ya hit the yrads, find out what other ECM may work in your ride.
For 1985, a Corvette ECM is accepted as a replacement for my Firebird V6 ECM.
I have a 1985 Corvette ECM in my ride, now.
DO NOT LOOSE YOUR ORIGINAL PROM, that is vehicle specific and if ya don't swap it into your replacement ECM, that can also bring ya troubles.
Best thoughts for a cheap repair bill!
My fuel pump exhibite same symptoms as you stated. Sorry my guess wasn't a good call for ya.

 

thanks KED,
for the prom .... I thought he knows about.

Horst

 

Well I have gathered everything I need to work on the ECM. I have run a diagnostic on it multiple times, but I still get the same thing, Code 12 (flash, pause, flash, flash, long pause) over and over again (yes I waited through three cycles and then about 10 more). So its not picking anything up. So I may still change the fuel pump despite the PSI readings. I figure if nothing else it can be preventative maintenance. This Saturday I will work on the ECM and Sunday the Fuel Pump.

Brad

 

good lock, let us know the results.

Horst

 

My 82 2.8 was the same way. When you would step on the gas it would kill it. Quite embarrasing actually. On occasion the check engine light would come on so I had that checked and nobody at my dealership even knew what the error code meant. My neighbor is a mechanic and he looked at my car and figured it was either ECM or one of many vacuum leaks on my cheap *** carb.

 

That is a good suggestion.
Check all hoses & connections.
Especially the on at back of engine by distributor driver side on the block.
That is main PVC feed system source.

 

Use a fuel pressure gauge for test the fuel pump,

a vacuum gauge for vacuum leaks, and

check the engine oil for water (coolant) in the oil. (pull off a small quantity of oil from the oil pan into a clear bottle, wait 1 day and check the oil for coolant at bottom).


Denis V,

And inform us about your tests.

 

sorry Dennis,

but I think that has nothing to do with coolant in oil
it's either air or electronic

Horst

 

Well I am going to check all of that out, I will be working on the ECM on Saturday. I haven't checked the pressure yet, so maybe thats it. I will let you know what happens after Saturday.

Brad

 

Well I will try this again next week. Weather sucked and since I have no cleaned out garage, I couldn't do anything this week except install a new radio. Soo, another shot weekend waiting for weather, I will keep you posted as to whether the ECM is the problem.

Brad

 

Took me about 1/2 hour to install/swap ECM.
Warm weather arriving very soon

 

Well after a few weeks of putting things off I am proud to say that warm weather finally arrived and with no rain... So I replaced the ECM and now the car runs like it never had a problem.

Thanks to all that helped, Case Closed! (for now )

Brad

 

Alright after I posted my Case Closed.... I find that I need to reopen it.

The old ECM was fried, but now I find the car doing the same thing. I finally broke down and took it to the Pontiac Dealership (I usually go to normal mechanics, but I find they have no idea what they're talking about either, so I figure to pay the extra and go straight to the source).

They have called me up and let me know that they feel it is the "Distributor Ignition Contact Module" and they also told me to replace the "Distributor Pick Up Coil".

I replaced the Cap, Coil, Plugs, etc when I tuned the car up. So I am guessing that is this is th TRUE problem, then maybe it ruined the brand new coil.

But I guess I just want your opinions, does this sound like the reason why my car is still doing the the things it was doing earlier.

I mean it seems to stay running longer now than it did before, but maybe thats just because its warmer which seemingly allowed the car to stay running longer the other day before the ECM was replaced.

Oh well, back to the drawing board.

Brad

 

"... I replaced Cap, Coil, Plugs, etc....", but "Ignition Module" is other thing. Did you replaced it too?.

 

Let's make it simple.
IF ya "rebuilt, installed" new parts under distributor cap,
Did you remove the distributor from the car to do the job?
Did you remove the distributor shaft from the distributor housing?
Did you then replace those items on the shaft base?
IF NOT then the dealership is correct.
YET if you can get car home you can rebuild the distributor yourself.
Do a search for my thread about distributor rebuilding.
The end result is very beneficial. Add new timing chain and you're good to go again!
Hope the results will work well for ya.

 

Getting the car home is no problem, I have a friend with a tow truck that has helped me out tremendously.

I only did the basic things with the distributor cap, coil, plugs, wires, etc. So now I need to work on the rest of the distributor.

Thanks for all the help, as always I will continue to update this until it is a done deal that way others can go through this same checklist.

Thanks,

Brad