Join Date: Jul 2004
Location: Franklin, Massachusetts, USA
Hey Airbeat... There can be many reasons for a backfire on start-up. It could be caused by a stretched timing belt, mis-adjusted pulse generator, lean mixture, arcing plug wire or fuel collecting in the exhaust pipes..
A backfire means the fuel/air mixture is ignitedinto the intake system of the engine. It can also mean the mixture isfiring out thru the exhaust system during post compression. In either case, I would suspectignition timing.
With poor fuel mileage, it may be caused by a sticking fuel metering rod inside one of the carbs which causes an initiallean mixture. As the engine warms up, that metering rod may slide into the upward positon, stick and cause a rich mixture.
We need to do more research for a proper diagnosis..
First, inspect the timing belts and cam positions for proper alignment.. If all is well, move on to the pulse generator and fuel delivery system..
Keep us posted on your progress..
Old Nam Vet
LZ English 66 - 67
New \'08 Titanium Nav
I\'m old and wise, but was once young and stupid.