Loss of power at full speed

[Doug Foster]

I have a 70hp johnson mod# j70plssd. On occasion I will be running and the motor powers down. It still runs but at lower rpm. Have had the stator, plugs, fuel filter, fule line, squeeze bulb and the anti syphon valve replaced. When it powers down it is very sudden. Have not hit anything.

 

[OBJ]

Re: Loss of power at full speed

Hi Doug.

Can you give us some idea of the rpms at WOT and the rpms when it "powers down"? When it does fall on it's face....is it around 2500rpms or maybe around 35 to 4500rpms?

If it's around 2.5K, it would appear the SLOW system is kicking in. This limits the engines rpm in case of over heat.

If on the other hand, it's like....3.5 to 4.5k rpm, then I would suspect your dropping a cylinder.....losing fire to one.

Some info would help.

Thanks.......Jim