Mercruiser I6 165 Engine Problems

[hondaracer8]

I have a 1979 Renken Ski Boat with a 165 I/O just this year after bringing it out of storage i began getting a back firing pop while at full throttle. now i am slowly losing rpm more and more i thought it was from old gas but it has now went through two tanks the only thing i can think of i did was run lead additive in the tank before i put it up for the winter. It is just slowly losing power now it takes longer to come up on plane.

 

[IVAZ]

Re: Mercruiser I6 165 Engine Problems

I agree with Bubba, it sounds like its lean. Check the timing also.
Lead additive should not effect its performance.