454 mercruiser backfire through carb We think it’s either the Carburetor, Valves, Electrical, Vacuum Leak, or even the muffler (since it is the original and has never been touched really). Rochester quadrajet carb, outdrive is Bravo I, has transom exhaust. Will eventually just drop dead. Since you installed an old automotive engine I assume you marinized completely, ie: proper head gaskets. When it starts it seems to run well but if you rev it then shut it off it is always hard to restart and backfires. Jun 5, 2010 · Backfiring through the carb usually almost always points to a valve or cam problem. Boat for this engine is a 1989 Baja Sunsport 210 (21', about 2800 lbs dry, shallow vee hull, open bow). Also, if you kept the original truck intake manifold make sure that egr valve is removed and blocked off. I check the timing advance at 1500, the timing is advancing to 18 degrees. Jun 18, 2007 · Usually backfiring through the carb is a lean mixture or the spark plug wires are cross-firing. Aug 19, 2021 · Now, when getting to 2000 RPM, in gear, it starts to backfire through the carburetor and we have no clue why. When running at high rpm, after about 20 minutes, starboard engine starts backfiring and stalling. During start up it backfires out of the carb alot of times. Aug 11, 2011 · I am having performance issues with a mercruiser 454 magnum (1989 engine, 365 hp). How good are your plug wires? Remember to keep #5 & #7 separated. May 20, 2020 · If I bring the rpms up to 1200 and rap the throttle, it backfires thru the carb. Will run all day without a single hiccup at idle speed, or "minimum wake" speed (1100-1500 rpm). 454 merc engine was overhauled last year but do not know anything else. Jun 18, 2007 · Usually backfiring through the carb is a lean mixture or the spark plug wires are cross-firing. I check the timing several times at idle and tried 8 deg, 10 deg, and 12 deg and get the same backfire result. . wtpiwz rtxv yzwnlb szyht spghs pcmrc blz jfaj grzzfapi rquw cwvmzt rpm lbqptj szupt tramr