1990 Chevy Lumina At a loss - fuel mix too rich -

1990 CHEVROLET LUMINA
104,560 MILES • 4 CYL • FWD • AUTOMATIC
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TERESAPUGH
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I have a 1990 2 door Lumina Euro - Bought the car a couple months ago - ran sweet for the first month then the ECM died - we replaced it as well as a faulty crank shaft position sensor and a worn alternator belt - car starts now but its burning a very fuel rich mixture - to the tune of about 3 - 5 miles to the gallon!! hooked it up to a sensor and got the code for a faulty MAP sensor - went to the parts store picked one up and installed it, and the car won't turn over at all. Replaced the new MAP sensor with my original one and the car starts but with the fuel ratio issue and super rough idle - its also blowing a LOT of carbon out of the exhaust - took the MAP sensor back to the parts store and got a new one in case it was faulty but had the same issue - engine won't even turn over with the new MAP sensor in. Any ideas what to do next?
Jun 17, 2008 at 10:14 AM
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MERLIN2021
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You might have to check the wires from the MAP right to the ECM...must be a short someplace, what code did you get?
Jun 17, 2008 at 12:38 PM
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TERESAPUGH
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The code I'm getting is 45 - rich exhaust - will check the wires as you suggest. Thanks :)
Jun 17, 2008 at 12:45 PM
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MERLIN2021
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You said you got a code for the MAP that should be a 31, 45 is 02 sensors reading rich...which they should do if this much fuel is burning, my suggestion is to look for a stuck injector or two...unplug any that arent clicking...or use a noid light, it should flash, not stay on solid...
Jun 17, 2008 at 1:00 PM
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TERESAPUGH
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We used a noid light - every thing looks fine - got a code for MAP Sensor before we tried to change it, now the only code coming up is the rich exhaust code. Someone suggested maybe a faulty temperature sensor but we haven't got that far yet - were looking to get it back on the computer this afternoon and verify the codes and maybe try to locate the temp. sensors - according to the book there are two. Thanks again for your help :) this thing is making me nutty, lol.
Jun 17, 2008 at 1:14 PM
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MERLIN2021
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Check the power and ground to the ECM, it sounds like it's stuck in limp mode, or open loop...ECT(temp sensor) can be checked with an ohm meter, should be about 50,000 ohms cold and drop to 177 ohms full warm...
Jun 17, 2008 at 5:51 PM
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TBDK87
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I had a similar problem on an 87 grand am. didnt burn that much gas though. Turned out to be a faulty o2 sensor. Try that as well. If the o2 sensor faults it will tell the engine to use more gas then reuired and make engine run rough. it will also still recognize a rich problem.
Jun 17, 2008 at 10:01 PM
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DNAPRORACING
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I went thru a similar issue, black smoke thru exhaust. new map/o2/fuel filter and pump, and injection service done. fuel pressure was fine. turned out to be the computer telling my injectors to stay open too long...
Jun 17, 2008 at 10:22 PM
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MERLIN2021
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Yeah...that's the ECM I mentioned above...
Jun 18, 2008 at 2:59 AM
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DNAPRORACING
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I got it replaced for $227. runs like a champ now. had me worried for a while after replacing the entire fuel system and the issue remained...
Jun 18, 2008 at 7:09 AM
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TERESAPUGH
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Thanks guys, for your time and insight. I'm going to take your advice and check the areas you suggested and go from there. Should have a good idea of wether we're on the right track or not by Monday and I'll be sure to let you know. Thanks again for your help, it's greatly appreciated - I'm definitely out of my depth as a home mechanic, lol.

:)
Jun 19, 2008 at 7:41 AM