RPM jumping from 8-1400

[stonebuster]

Last week running four knots through the harbor, my rpms were jumping around varying 2-300rpms. I've changed the plugs since which looked pretty normal. I changed the 10 micron raycor and it did have about half shotglass of water and some small debris in it. After changing plugs and raycor, at the dock in nuetral the RPM's were steady except when I tried holding it at 1300-1400 when it would jump from 800- 1400. It seemed the longer I let it run at that range the worse it got. The fuel filter on the motor itself looks normal with the red ring at the bottom where it should be. I guess the next step would be to pull the motors fuel filter off and clean it? Any other ideas on what could be the problem? It's an '04 225F Yammy.

 

[Megabyte]

Certainly sounds fuel related to me.
Maybe run some fuel injector cleaner through it off of a portable tank?

Sorry, but any other ideas I'd have would be pure speculation.

 

[BradV]

Run some startron in it. If you had water in there or if the boat sat for a while it needs to get cleaned out and the alcohol nature of startron sucks it up pretty quick. I would also change any fuel filter on the motors that you see if you found any water in the big filter.

 

[TopShot25]

I had something like this happen to me once, but it was at cruising speed. RPM's would at random just go up or down 3 or 400. It turned out to be a loose ground wire. I ended up finding it when I would hit my trim switch and it would kill the engine temporarily. Anyway check your ground wires, it may be the problem.