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10-27-2021, 03:11 AM | #1 |
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Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
Posts: 1,846
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Check engine light flashing
I have a 91 C3500 Cheyenne (No Frills), and last year I had a no start issue,
Starting with the Fuel filter, then fuel pump, I replaced everything in the fuel system and rebuilt the TBI. Also I replaced the ignition system components, and still no start. After talking with a few heavy mechanics, we summized that the ECM was bad. I ordered a replacement and installed it. It started and runs fine, but from the first time, the chech engine light seems to go through a cycle of “Quick Flash” then on to a slower fash, then wil come on steady, then sometimes it will flash randomly.. One other thing is that it seems to run really rich when I first start, like it’s getting too much fuel, but runs fine after warming up. All the electrics on the TBI are hooked up correctly. It flashes a “Bad O2sensor, but I’ve put two on it and nothing’s changed. I was told it could be caused by the ECM not being properly set. Anyone have any insight? |
10-27-2021, 08:29 AM | #2 |
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Join Date: Jan 2006
Location: Big Pine Key, FL
Posts: 745
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Re: Check engine light flashing
Did you get the same number ECM as the old one? Also, was a chip already installed or did you swap your chip into the new one? Any info on the numbers on the ECM or chip you can provide would be helpful
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Mike |
10-27-2021, 11:06 AM | #3 |
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Join Date: Jan 2003
Location: Safford,AZ
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Re: Check engine light flashing
Third Generation Camaro and Firebird forum has a ton of trouble shooting TBI problems.
Yes the help us truck people as well. https://www.thirdgen.org/forums/tbi/ |
11-01-2021, 02:48 PM | #4 | |
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Join Date: Apr 2015
Location: East Tn (In the heart of the Smoky Mtns)
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Re: Check engine light flashing
Quote:
It gets programmed according to the VIN, and yes, I put the Blue “Chip” from the original into the New. As I said, once I put the new one it it fires up and runs fine, it’s just that light irritates me that I can’t figure out why it’s signaling |
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11-01-2021, 04:12 PM | #5 | |
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Join Date: Jan 2006
Location: Big Pine Key, FL
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Re: Check engine light flashing
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Mike |
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11-01-2021, 11:59 PM | #6 | |
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Join Date: Jun 2014
Location: Orlando Florida
Posts: 1,598
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Re: Check engine light flashing
The light flashes when you start it with the diagnostic terminal grounded, so maybe you have a bad wire.
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