loss of power at high rpms

[Raymorgan]

I have a 2001 johnson 115 ocean pro that I just cannot get to run right. When i first took it out this season, it ran ok until i ran it at almost full throttle. Soon after i did, it began to sputter real bad to the point that it wouldnt plane out. I took it to a mechanic who advised me to remove the oil injection, replace the fuel pump (due to fuel prime and oil issues). When I got it back, I ran it for 15 minutes or so at no higher than 4500 rpms (est). On the way back to the dock, I decided to open it up a little, and I got to 4900-5000 rpms and it began to sputter the same way as before. Does anyone have an idea of what may be causing this?

 

[tassie ben]

Re: loss of power at high rpms

could be like the mechanic said...fuel prime and oil issues..high rpms could be gettingtoo much oil in the mix for it to fire properly or something up with fuel delivery at high rpms (jets?? not enough fuel rather than too much oil)..good luck

 

[tashasdaddy]

Re: loss of power at high rpms

i assume you did go to a straight fuel pump, and premixed fuel. sounds like you have a fuel delivery problem, dirty high speed jets.

 

[CharlieB]

Re: loss of power at high rpms

How old are your spark plugs?
What plugs are you using?

Increasing engine load places more demand on the ignition system, faililng spark plugs begin to show up are high speed misses, progressively getting worse and worse until the motor barely idles even.

Hopefully there is nothing wrong but time to change plugs.

 

[Raymorgan]

Re: loss of power at high rpms

yes, i did go to premixed fuel. There are jets for high speed operation? The spark plugs were replaced last year.

 

[Raymorgan]

Re: loss of power at high rpms

Anyone else have any ideas?

 

[Kettler]

Re: loss of power at high rpms

Have you tried replacing the plugs yet?

I would be curious to see if it worked.

I have a similar problem and am going to start with new (cheapest place to start) plugs.

Let me know...Good luck

 

[Raymorgan]

Re: loss of power at high rpms

ill probably try to replace them. But if it were the spark plugs, why would it run ok at 4000 rpms but not at 5000 rpms? Oh, and by the way, once it starts it continues at any rpm level.

 

[Raymorgan]

Re: loss of power at high rpms

Thanks for the input. Is there a possibilty it could be the power pack?