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Well this is really on a boat with a mercruiser engine. It is a normal car engine for the most part. It is a mercruiser 165, 250 hp inline six with very low hours. The engine was running perfect untill it warmed up(Not hot). Therefore I replaced the distributor cap, rotor, and coil. Now my engine is backfiring under a load. Any posibilities? Remeber that the engine ran very well cold. It would pull a skier right out of the water, yet after 30 min on the lake it started cutting out. It no longer cuts out on me anymore just backfires!!!! Please advise me what I should do. Thanks Reinhardt
I also rebuilt the carburator thinking that was causing the engine to cut out. But it changed nothing, therefore I replaced all plugs, distributor, rotor, and coil. Thanks again
I hope you changed all fuel filters???
did you cross a plug wire?? Also pull plugs again see if you didnt bend an eletrode..(I did that) Did you change plug wires??
There could be a couple problems.1 is this motor carb or injected? It sound like a lean run problem,oooooor vacuum leak,ooooor A week lifter.Also I have seen bad coils do this too.Condencer if it has points.
This happened to me on the Chevy 454 in my RV. After replacing plugs, wires, cap and rotor, it ran fine cold, but when warmed up, began backfiring out exhaust. I asked a dozen people what the problem was and, of course, got a dozen different answers. The solution to my problem was the module in the bottom of the distributor. As it was explained to me, it runs fine while cold because there is a small crack in the circuit board inside this module. When the engine heat finally gets to it enough to expand the crack, this leads to poor spark, therefore it backfires when burning off unused fuel in cylinder. While I had the distributor apart again, I also replaced the coil just to be on the safe side. Hope this helps!
A bit of definition here. Backfire is a burning in the intake system and popping back out of the intake manifold, more commonly known as "spitting back". Explosion(s) in the exhaust system are technically known as "after-burn" and are the result of unburned fuel entering the exhast system and then being ignited by a subsequent ignition source. The unburned fuel gets into the exhaust system because of: 1. Ignition misfire. 2. A mixture in a cylinder that is too lean to burn. The next time the engine dies, check the fuel in the carb.
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