Backfire Causes

Old 11-02-07, 10:09 AM
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Backfire Causes

Anybody ever heard of an alternator going bad and causing backfiring? I drove 180 miles in my 1986 Chevy, 305ci with no problems. About 3 miles from destination pulling away from red light the truck shuddered slightly lost power began backfiring and blew the muffler apart at the seam (8 inch seperation). The engine then died, voltage gauge was at 0 and the usual clicking sound was heard trying to retstart it.
I was told a failing alt could cause this by 2 people, I had never heard of it before. So I am asking those with more know how than I have. I have changed the alt and am preparing to go out and buy a muffler,so before I blow another one up I have come here.
Old 11-02-07, 10:27 AM
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There is a logic that could point to something like that. It would be indirectly caused by the failing alternator.

It would be low voltage = poor spark = accumulation of unburned fuel in the exhaust. From that point it would be a simple matter to get a combustion flame to ignite it.

A backfire in the exhaust that would tear apart the muffler would need some unburned fuel to work with.

In the early sixties a teenager trick was to adjust the choke to richen the fue/air mixture, then tee into a spark plug wire with a long wire that would be ran to a spark plug fitted into the end of the exhaust pipe. The accumlation from the overly rich mixture would be ignited causing the backfire (quite loud). That arrangement didn't tear anything up (except for the nerves of a few local residents) because the flame front was well past the muffler.

Hope this helps,


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