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Old 03-04-2005, 01:54 PM   #1
bbchevy
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backfire... KA-POW!!!

what causes backfire on a carburated motor. the choke is unhooked and when the motor warms up it will backfire and lack just about all its power going down the road. mixture too lean? too rich? i cant even pull the truck out of the driveway. maybe the plugs arent fireing? double checked all the wires and they are all going to the correct cylinders.wires and plugs are all new. so is the cap and rotor. yea i think im lost
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Old 03-04-2005, 02:00 PM   #2
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sounds like your timing maybe off...
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Old 03-04-2005, 02:21 PM   #3
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i had the same sorta thing, when it got up to a certain rpm it would backfire and gutless as hell. but it ended up being the collector gasket blew out
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Old 03-04-2005, 04:46 PM   #4
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It's running lean. You have a vac. leak somewhere, or the carb is not functioning properly.
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Old 03-04-2005, 05:47 PM   #5
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Backfire out of the carb is to lean
Out of the tail-pipe is to rich.

But be sure your timing is correct too.
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Old 03-04-2005, 06:01 PM   #6
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Sounds like the timing to me. Did you put a Timing Gun on it yet?
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Old 03-04-2005, 06:09 PM   #7
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Yeah, I was having the same problem and it was my timing. Either that or a vacuam leak.
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Old 03-05-2005, 12:00 AM   #8
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did you check the carb gasket?

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Old 03-05-2005, 01:44 AM   #9
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I actually had my Q-Jet backfiring on me when it was waayyyy too rich just before I took it off. It was so rich that it was fouling plugs to the point where they wouldn't even fire within a week!! And it also lacked power like you say. But Yeah, It is most often like everyone else said-Lean or maybe a Vacuum leak. I have also heard of ignition modules doing that, but I'm not sure what setup you have.
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