What causes backfiring?
Postmaster
Joined: Mar 2003
Posts: 4,038
Likes: 2
From: Spokane WA
Im watching this thread, sorry to bump it when its 2 days old, are timing and mixture the only reasons it would backfire through the carb? stuck or sticking valve maybe? I have the same issue, but only via the info PO gave me when I bought my truck, it hasnt run yet since ive owned it, just getting ideas ahead of time.
Hotshot
Joined: Oct 2002
Posts: 18,488
Likes: 22
From: The Big, Oregon
stuck valve can cause that, but will also make a skip all across the rev range. A blown head gasket can as well, or a burned up intake gasket. In some instances, a plugged cat can make an intake backfire as well.
Moderator
Joined: Dec 2001
Posts: 22,436
Likes: 17
From: Louisville,Ky.
Old bad gas can do it too, if it is degraded.
The main reasons for backfiring thru the carb are Slow timing/bad vacuum advance, lean mixture (vacuum leak/bad accelerator pump), stuck or bent intake valve, plug wires crossfiring, or a jumped timing chain causing the valves to open at the wrong time.
The main reasons for backfiring thru the carb are Slow timing/bad vacuum advance, lean mixture (vacuum leak/bad accelerator pump), stuck or bent intake valve, plug wires crossfiring, or a jumped timing chain causing the valves to open at the wrong time.
