5.7 mercrizer backfires no power?
I replaced spark plugs, coil wiring , rebuilt carburetor and cleaned fuel tank and replaced gas. When the engine is cold it runs for 3-5 min with no problem as soon as it gets warm it starts to backfire and has looses power. i put cleaning stuff into fuel.
Update:i have tried runing the boat without fuel cleaner but had same issue. i found a valve between gas tank and engine that was all clogged up . will replace it today and test the boat tomorrow. thanks for your suggestions.
Comments
Take it to the shop. . . let the guys with all the know how, expertise, experience, and proper tools check it out for you. . . Believe me - it will save you a lot of headaches, heartaches, and probably money, in the long run. If you miss diagnose this problem - it could easily cost you an engine
I've had to think about this more than usual.
it might be related to the fuel "cleaning stuff" . A lot of these products have solvents in them, that have unintended consequences. So, did you add before or after this started?
If timing where out that would show on start up. That "warm up" part is key. What that means is that the oil was cold and as it gets warmer, it thins, thus less pressure. That might indicate a valve lifter problem. Thus the backfire. You need to isolate that problem. in order to back fire a intake valve has to be open and fuel ignited. This can be diagnosed because that cylinder will not give you power.
However, you need to eliminate other possibilities before going into the heads. Do basic ignition and compression test.
Have you checked the timing because if it is not set properly your engine will backfire.