Mercruiser, seems to be running out of fuel.

Question
i have a 1989 larson w/ twin 260hp merc's, i just had  one of the long blocks replaced, that engine worked well for aobut 16 hours now when the engine is powered to get up on plane, the engine seems to simply run low on fuel making the engine backfire and lose power.  my mechanic has done the folowing. Changed the fuel filter (the fuel seems to be very clean so we are ruling out the ethonol cleansing the tank etc.) he replaced the fitting at the top of the fuel tank that connects to the fuel hose, replaced the distrbutor, rotor, sensor, had the carborator taken apart and cleaned. He's running out of options and my bill is getting larger by the hour.  the 2nd engine is running fine.  Any ideas? MIke Ward 603-621-0254

Answer
Hi Mike - Thanks for selecting the undersigned to reply to your question. If you have only 16 hrs. on the engine, did you get a warranty with it?

I'm not a mechanic, but I wasn't aware that an engine low on fuel would backfire - I thought that occurred when there's too much fuel in the combustion chamber. I would have thought both engines receive fuel from the same fuel tank, so how could one engine "run low on fuel"? Anyway, you didn't mention about checking the fuel pump and strainer. Is it possible you might have a bad head gasket? Check for moisture on the spark plugs. Perhaps the water journals are blocked, and the engine isn't being cooled properly, so it heats up to the point of almost seizing and eventually stalls.

If all else fails, change mechanics - and use a qualified Mercury Marine facility.

Safe Boating
Ron