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Posted: 11/25/2003 4:09:45 AM EDT
[Last Edit: 12/7/2003 7:40:08 AM EDT by 2_of_5]
When I bought my new truck, I gave my old 94 Cutlass Supreme 3.1 L to my 16 year old son. Last week he was just leaving the parking lot at school when it died. It would crank and catch for a moment then quit. After I towed it home, I first suspected someone put water in his gas tank, so I added two bottles of Heet (dri-gas) and changed the fuel filter. I pumped about half a gallon out of the fuel line while I had the filter off, and there was no indication of water (after the Heet though).

I can get it to start after all, but it will not take throttle at all. Idling is fine, however the idle speed will creep up to around 2500 rpm eventually. It ran fine immediately before this episode, so it appears something suddenly failed, as it doesn't appear to be water in the gas. After digging through the service manual, I'm suspecting it may be the MAP sensor (manifold pressure) which if I understand it correctly regulates fuel flow in off-idle conditions.

Should this be where I continue looking, or have you seen this before and know of the fix?

Thanks
Link Posted: 11/25/2003 4:18:20 AM EDT
Could be that or the fuel pump went tits up on ya. Had this happen to my truck a few months back. Fuel pump just up and died all the sudden. Same symptoms you have.
Link Posted: 11/25/2003 4:21:25 AM EDT
Could be. It seems to pump ok volume wise, but I didn't check the pressure. I'll look at that... thanks.
Link Posted: 11/25/2003 5:07:19 AM EDT
Hook up a pressure guage and check fuel line pressure. Auto Zone should have the tools you need. While you are at it, borrow the code scanner from them as well. Sounds like either insufficient fuel pressure **or** the AIR sensor. The AIR sensor detects airflow into the intake tract and the computer uses this information to meter fuel. A buddy had an 86 Camaro, this sensor went out on his car and it did what you describe. Good luck and let us know what you find out.....
Link Posted: 11/25/2003 5:28:02 AM EDT
[Last Edit: 11/25/2003 5:37:53 AM EDT by DriftPunch]
I had a 91 lumina with the 3.1. About once every two months, it would develop a little backfire(not a big blast, but you could tell that pressure was sent back through an intake valve) while starting that would overpressure the vaccum system. This system normally has negative pressure, so the fittings are sucked tight. This overpressure would reliably blow out a large loose vaccum fitting on top front of the intake. It was a 3 in one type of fitting, and when it was out, it idled very high, and had zero power(not enough to drive), however it didn't cut off (unless you tried to drive). The first time this happened, I was really worried that it was really screwed up. When I opened the hood, it was pretty obvious what happened, so I simply put the fitting back. It always ran fine once it was replaced (put back).
Link Posted: 11/25/2003 12:05:33 PM EDT
Be sure to post an update...
Link Posted: 11/26/2003 1:52:27 AM EDT
[Last Edit: 11/26/2003 1:53:06 AM EDT by dsr611]
[;D]Did he just fill it up with gas? If so, money says it is the fuel pump!!![;D] Just kidding! I had an '86 Monte Carlo and stopped and filled up with gas one night on my way home. Went in the gas station to pay and get a Dr. Pepper, came back out, and car would not start!!! Yep, you guessed it, fuel pump went out on it!!! Few years later, I had an '89 Bronco II. Stopped one day on the way home from work and filled up with gas. Went in to pay, came back to the Bronco to go home, and it wouldn't start. Yep, fuel pump out again with a full tank of gas!!! It is a bitch dropping a gas tank when it is full!!!
Link Posted: 11/26/2003 2:07:42 AM EDT
With what little info you are providing, I'd be looking real hard at the mass air flow sensor, fuel pump, and crank sensor. Good luck. Panzer Out
Link Posted: 11/26/2003 10:21:34 PM EDT
Throttle Position Sensor
Link Posted: 11/27/2003 4:09:55 AM EDT
Ok, we determined the gas is not contaminated, a mechanic friend thought it would be the MAP sensor --- he didn't want to have to drop a full tank to flush it if he didn't have to. Put a new sensor on last night, with no improvement. I pulled the new fuel filter and backflushed it to see if there was any junk it was picking up. There was metal dust in it, so it does look like the fuel filter is toast.
Link Posted: 11/27/2003 7:08:44 AM EDT
dude, you really need to look at the fuel pressure, there is a shraeder valve on the fuel rail, use it, get a pressure gage from someone, buy one at autozone, and return it when you are done, do not guess at which parts may be bad, you will go nuts, and go broke, if it has good fuel pressure (30psi+) you need to check for dtc's you can check the dtc's on a 94 ecm with a paperclip, you count the blinks, then get in touch with me, i am a gm master mechanic, i can save you a ton of money, but you need to stop guessing, and start troubleshooting, it is easy
Link Posted: 11/27/2003 7:26:25 AM EDT
2 words Fuel Filter. In a TBI engine, it's located at the rear of the Throttle Body where the fuel line is attached. Just a little cartridge device, and it'll allow enough flow to get the car rolling before it dies. And it doesn't come on sloowwwly either, one day it works and the next it doesn't. Also it's a cheap fix, or try before laying out big bucks on relacement pumps etc. Does the winner get a 20rnd mag?
Link Posted: 12/7/2003 7:32:29 AM EDT
Fuel pump was the culprit. Changed it out -- parts and labor for just $250. Thanks for the input -- arf.com is a cornucopia of knowledge....!
Link Posted: 12/9/2003 1:59:36 PM EDT
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