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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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Ihave a 1999 Campion cruiser with single Mercruiser 5.7 Bravo

Customer Question

Ihave a 1999 Campion cruiser with single Mercruiser 5.7 Bravo drive , low hours, 2 bbl carb, 250 HP.. Starts great, runs great for about 15 minutes, then starts to pop and spit in the 2700-3700 range. Not a backfire, but almost sounds like super retarded timing. If you press to WOT, it is more or less OK (no popping) , same at idle. Installed new gas filter, checked carb filter, both clean. Changed ignition coil, it actually seemed a bit worse with new coil?? The old coil was bleeding out some grey tarry looking stuff, so I thought I had nailed it at that point. The boat had been in storage for a couple of years before I bought it. Any ideas on cause and cure? I noticed also that when you nail it from stop , when this is going on, that I hear some ignition pinging, that I don't hear when it is cold.If you rev it up in neutral, the trouble range is perfectly smooth. Worst spot is minimum plane, about 3300-3400 rpm. Have not run a lot of fuel through it yet, but fuel esmells fresh, plus I have added some new.
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.
Hello my name is ***** ***** am I speaking with?
What more can you tell me about the engine? When did it last make full power? When was the last time it had a full tune up? How old if the fuel?
Customer: replied 1 year ago.
Mark Belair. It makes full power OK, it is the popping at midrange that is the problem, only when warmed up fully (15 mins.) . I have already burned a tank of fuel and added fresh. Plugs were good and I put new distributor and rotor in to help solve problem.
Expert:  Jason replied 1 year ago.
Hi Mark.Have you had the carb rebuilt yet?

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