Loss of RPM's at full throttle

[Kokomo36]

I have a 2003 Merc 15HP - 2 stroke. It generally runs good but, it started losing rpm's when at full throttle. It will drop rpm's for a moment and then regain full rpm. It will do this every few minutes.

I cleaned the fuel tank, replaced the fuel/water filter, and added all fresh fuel with stabilizer. No improvement... Any suggestions? Thanks !!!

 

[Mike722]

Re: Loss of RPM's at full throttle

Check fuel tank vent , fuel pump, and for any air leaks in fuel system.

 

[canadian_fisher]

Re: Loss of RPM's at full throttle

Sounds like a fuel problem..... I too would start to check for a fuel leak.
Also, it wouldn't hurt to check your plug wires for a dry connection or something loosing contact when bouncing around the lake.
When's the last time you did a tune-up and change the plugs?

Good Luck... CF

 

[Kokomo36]

Re: Loss of RPM's at full throttle

I just had the carb rebuilt and changed the plugs. I agree that it sounds like a fuel problem. Not to be too stupid on the subject (but I am), I see no sign of a conventional fuel pump between the fuel line and the carb??? Where exactly is the fuelpump???

 

[Mike722]

Re: Loss of RPM's at full throttle

Would need to know the serial number of your engine, but it looks like the fuel pump maybe part of the carb.

Go to dougrussell.com or mercurypartsexpress.com and you can look up parts with your serial number. If you have the serial number try mercury first, if not with dougrussel you can search by model.

If you had someone rebuild the carb, I assume they looked at and rebuilt the fuel pump if it is part of the carb.

Was the engine having this problem before the carb was rebuilt? If not something might have been put back wrong in the carb.

 

[Kokomo36]

Re: Loss of RPM's at full throttle

The Serial # is OT599586. Yes, I had a similar problem but it got much worse to the point it wouldn't run. A dealer in maine rebuilt the carb but the problen re-surfaced in a few weeks.