Backfires on acceleration

[JASinIL2006]

My boat has a problem when we accelerate hard, like when trying to pull a skier. When I hit the throttle, about 50% of the time the boat chugs and backfires, and then catches and accelerates as you would expect. The other half of the time, it accelerates pretty strong (although I suspect I could re-prop to get a better holeshot). Other than during this sort of acceleration, the motor runs smooth and strong. I'm reasonably sure I don't have contaminated fuel problems; the water-separating fuel filter didn't have any water in it, and I've run many tankfuls of gas and it's always done this backfiring thing.

In researching this on the forum, it sounds like some sort of carb issue is likely the problem. Is this something I can troubleshoot and fix myself? If it is, where do I start?

Thanks for the help!

Jim

 

[oxfordgt]

Re: Backfires on acceleration

Sounds like an accelerator pump problem. The backfiring is a lean condition meaning it's not getting enough fuel. Since it catches itself that points to accel pump. What carb do you have?

 

[JASinIL2006]

Re: Backfires on acceleration

I have the Weber 4 barrel carb.

 

[JASinIL2006]

Re: Backfires on acceleration

I'm going to have the boat up at the lake for a couple of weeks. I have the Merc service manual, but does anyone know of any resources I can download and take with me? The manual assumes more familiarity with carbs and engine adjustment than I possess. I'd like to learn, but I think I need to start with something more basic. Any suggestions?

Thanks,
Jim