Hi all

Last night I drove the car home and it ran fine. Today I went out to start it and it will fire and up and then immediately die. When it starts, the engine will rev to about 3000 rpm'* and then quit. If I keep my foot on the gas and keep it revving about 3000 rpm'* or so it will stay running, not very well but it does stay running. It seems quite "boggy" when I am doing this.

I had my wife come out and start it and kept it running while I looked at the fuel pressure guage. It remained above 40 PSI during the test. The car has been sitting for about 30 minutes now and the pressure is setting at about 37PSI.

The only thing that I have noticed lately is that it seems to crank a little longer than normal before it starts, but once it started it ran fine. About 2 months ago I replaced the MAP sensor with one from Advance Auto.

The car has about 194,000 miles on it and usually runs fine. The upper intake has also been replaced.

Any Ideas? Will the car run if I unplug the MAF sensor or not. I thougt I might do that for a test, but I have not yet.

thanks for looking
Andy King

My guess at the moment is the MAF. Unplug it and observe.

Just came in from uplugging the MAF and that did not make a difference. When I start it, the engine will start to race up to say 3500 RPM'* and then it falls back and immediately stalls. If I gvie it about 3/4 throttle it will rev past the 3500 rpm range and then start to stall. I have to release the throttle and push it down hard again and the car will again rev but only for a second or so and then tries to stall again.

Just for the heck of it, I plugged the MAF back in and then unplugged the MAP sensor and that didn't make a difference either. I did that because the MAP is not a GM original part.

Any other ideas?

What are the symtoms if your throttle position sensor is open and not giving any input to the PCM? Just a thought.

thanks for your help so far.

Andy King

im assuming that there are no codes thrown, or stored

Silly thought but you didn't possibly get water in the fuel did you? Sounds similar to needing dry gas. Doubt it'* that easy though.

Fuel pressure seems low....I would suspect either a plugged filter or failing fuel pump....good luck!

What are the specs on the fuel pressure? What should I be seeing? What should the pressure be with the car running?

When I get back from church this morning I plan on tackling it again. I sure would like to get it running by this afternoon so I can use it for work tomorrow.

I have been doing searches on the board and there are several parts that are common failures on these cars, but I don't think they would apply here.

Crank sensor--If it is bad, would the car even start. Mine starts but immediately dies.

FPR--If that was bad, would it maintain the 40 psi or so that I am seeing with the car revving at and around 3500 rpms.

Today here is what I plan to do. I am going to clean the AIS motor pintle. Check the throttle body for tightness, reseat the PCM connector and tap on that a time or two.

Inspect the throttle body intake for cleanliness and clean if necessary.

Probably also change the fuel filter I am hoping it is not the fuel pump as I have about 7/8 of tank of gas.

thanks for all of your help
Andy

First off, when you unplugged the MAF and MAP sensor[*] did it throw the SES light? Did the SES light go off after you plugged them back in? If it did not, you may want to get the codes read.

Crank Sensor: Car will NOT run if this fails. It either works, or it doesn't. The Cam sensor could cause problems, but that would set off a code.

FPR: This seems to be in order if you have 40 PSI running, and 37 PSI after sitting. There will always be bleed down. I think 40-50 PSI is the sweet spot on these cars, but I could be wrong.

Checking the TB is a good idea, it is very possible there is a leak there, which is causing the high idle and stall [the PCM wants to lower the idle, so it closes the IAC more and more, doesn't see a decrease, then pulls timing or fuel.. whatever the case. Resetting the PCM is a good idea, tapping on it.. I wouldn't just yet. Try everything else, and then see what happens.

Don't worry about the Fuel Filter. I have the original in my '89 and it still flows just fine. Unless it is due for a change, I wouldn't do it. If you have owned the car for 12 months, and nobody has replaced it during that time, then go ahead and replace it.

BillBost has a good point. You may have water in your gas. It does sound kinda like water in the gas since it runs so rough.. and maybe a combination of the TB being loose, and bad gas. Did you fill up with a little gas the day or day before you had the car running last, then park her and now she'* like this?

Does anyone know if fuel or water sinks to the bottom [which one is more dense]? Maybe you have just enough water that, that is what the Fuel Pump is pulling in.. and not enough gas? I think water is more dense than fuel, because I know water is more dense than oil..

Let somebody comment on this before doing it, but whenever I had bad gas in my Lawn Mower, Weed Wacker, Blower, Chainsaw, etc.. I would always run some carb cleaner or starter fluid through it, and that would usually get the engine running well enough to clear it out. I KNOW starter fluid will kill your MAF sensor, so you would want to pull that.. but maybe spray it in a vacuum line? Maybe get the car running decent [not saying starter fluid will do this, but I have ran my car on TB/Carb Cleaner... not on purpose, but when I cleaned the TB and Intake, I just sprayed the crap in there.. and pulled the Fuel Pump Relay]. PLEASE, for the sake of your car, let somebody comment on this BEFORE doing it. I have already learned that 2-stroke engines are nothing like car engines.. so this could do damage to your engine.


-justin