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Running rich and backfires, bad timing?

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Old Oct 10, 2017 | 02:26 AM
  #1  
dibella989's Avatar
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From: Indiana
Car: 1988 Trans Am GTA
Engine: 305 TPI
Transmission: 5-Speed
Axle/Gears: 3:45
Running rich and backfires, bad timing?

Not too long ago I put in a new ecu, and all was going well for a few weeks. Then I started to notice I can smell gas when I'm sitting at an idle, and the amount of exhaust smoke I'm producing is large. I already had a good amount but it was mostly at startup or if I was doing a pull, now I can see it when I'm idling, and a person driving behind me can see it. If I let off the throttle and leave it in gear every now and then I have a very loud backfire, almost like a gunshot. Could I be running more rich and such because my timing is off? I really don't know much at all about timing, so I have no idea what I'm doing here, any suggestions or information would be greatly appreciated.
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Old Oct 10, 2017 | 02:31 AM
  #2  
Tuned Performance's Avatar
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From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: Running rich and backfires, bad timing?

Have you checked your fuel pressure and see if it drops rapidly after the initial prime. Check engine light on ?
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Old Oct 10, 2017 | 04:05 AM
  #3  
dibella989's Avatar
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From: Indiana
Car: 1988 Trans Am GTA
Engine: 305 TPI
Transmission: 5-Speed
Axle/Gears: 3:45
Re: Running rich and backfires, bad timing?

Originally Posted by Tuned Performance
Have you checked your fuel pressure and see if it drops rapidly after the initial prime. Check engine light on ?
No check engine light, and I have not checked fuel pressure, should I go rent a gauge to see what it's at?
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Old Oct 10, 2017 | 11:09 AM
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Tuned Performance's Avatar
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From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: Running rich and backfires, bad timing?

At prime the fuel pressure will rise to about 43.5 psi. If it drops quick after the prime you have a leak in the system. Your looking at a ripped fpr diaphragm or leaking injectors. To see if it’s the fpr you can pull it’s vacuum line to see if there is evidence of fuel. There are other things that can cause the overly rich condition. Cts , tps or bad maf to name a few.
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Old Oct 10, 2017 | 11:15 AM
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From: Los Angeles
Car: 1989 IROC Convertible
Engine: 350 TPI L98
Transmission: WC T5
Axle/Gears: 3.42
Re: Running rich and backfires, bad timing?

Stuck injector?
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Old Oct 10, 2017 | 11:25 AM
  #6  
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From: Mile High Country !!!
Car: 1967 Camaro, 91 z28
Engine: Lb9
Transmission: M20
Axle/Gears: J65 pbr on stock posi 10bolt
Re: Running rich and backfires, bad timing?

Originally Posted by Tootie Pang
Stuck injector?
That’s what I was thinking it could possibly be.
You can also pull plugs to read to see if it’s isolated to one or all cylinders.
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