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?

 

[kghost]

Good tune up, new points rotor and condensor, Make sure spark plug wire firing order is correct.......
Set to specs
Check distributor shaft for side to side movement. The 4 cylinder and six cylinder distributors are on an angle and the housing bushings wear out!

If tune up is good, shaft play is good, Gas supply is good, and carb function is good then maybe be a worn exhauist lobe on cam shft