mercruiser 150 hp inline 6 backfire under load

[moyer7373]

I reciently bought a new boat that has a mecruiser in line 6 150 hp. Under load it backfires around 2000 to 3000 rpm and bogs down. Any advice?

 

[guyjg]

Occaisional backfire can be a timing issue...worn parts or spark plug wire crossover. Also a caused lean condition...not enough fuel getting to the cylinders. Fuel filter could be clogged. Clean the spark arrester. Check the timing. Check the spark plugs for a brown burn pattern. If it is grey or offwhite it is lean. A burnt valve will make it run rough and backfire more. Get back w/your findings.

 

[makomark]

Also, check that the distributor advances the timing with rpm...

Fuel pump could also be past its service life, especially if original...

BTW, I'd bet you have a 160hp, not a 150hp