Jeepster-American Jeepster ClubThis board is maintained by the American Jeepster Club to support all discussions of Jeepster Commandos and Commando models of Jeeps. Please visit our club web site for more information at www.off-road.com/jeepster
My Jeepster is a 69 with a 225, TH400 auto, power brakes and rochester 2 barrell with stove pipe choke. Sometimes when I go out to crank it the next day, it backfires out of the tailpipe on the first revolution of starting it. If it has been sitting a couple of days before I drive it again, it does not do this. The only running problems it has is a little stumble on acceleration. Just wondered if anybody has ideas on where I might start troubleshooting.
I had the same problems at one time. It was a loose screw inside the carb barrel causing fuel to pour into the intake manifold, especially when first shut off. If I tried to start it up right away it would backfire and flood easily.I happened to have the air cleaner off while I shut it down and looked down the carb to see plenty of gas pouring down the intake. Maybe this is your problem also. I ended up putting in a carb rebuild kit to solve a lot of drivability problems.
I agree with gschlachter. Since you say it doesn't do it after sitting a couple of days, it sounds like you're probably loading up the engine with gas. If a piston happens to be at or near TDC on the exhaust stroke, the vapors from the gasoline can migrate into the exhaust, since at that point in the combustion cycle both the intake and exhaust valves are slightly open on that particular cylinder. When the engine fires, you end up with ignition of the fuel vapors that have not evaporated, causing an explosion outside the engine in the exhaust manifold. After sitting a couple of days, the gas would have time to totally evaporate, so there wouldn't be the resulting ignition of the excess fuel vapors.
Your problem might be coming from a different source than what he had (float level too high, float sticking, etc), but the results would be the same.
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Backfire Problem Please Help 
Linear Mode
