Losing power on 2000 2 stroke Johnson 70hp

[Collinsonbailey]

The motor runs fine on muffs under no load. When put in water it will run until full throttle then it will loose power and drop revs. I have just cleaned all carbys. Replaced spark plugs. Have checked ignition coils and lead. Wondering what else it could be or if anyone has any ideas on what to check.

 

[Chris1956]

Pump primer bulb at high speed and see if she will keep running. If so, it is likely a fuel pump or fuel line issue. My SeaRay I/O did that and it turned out to be a partially clogged filter on the fuel pickup.

 

[Collinsonbailey]

Pump primer bulb at high speed and see if she will keep running. If so, it is likely a fuel pump or fuel line issue. My SeaRay I/O did that and it turned out to be a partially clogged filter on the fuel pickup.

Yes have tried that and it doesn’t seem to make a difference.

 

[racerone]

They all run great on muffs.---Even in gear it is still neutral , as the prop does no work.-----Post the actual results of a compression test.-----Have you checked water pump impeller / thermostat??----Could be overheating going into S.L.O.W mode.

 

[Chris1956]

Is there a filter between the primer bulb and the carbs? Is it clean?

 

[saltchuckmatt]

Does it have the vro installed still?