loss of rpm at high end

[ray21]

hey guys....on my 1990 force 150, i can only run about 2500 rpm wot. i have checked compression, 150 on all 5 cylinders, which is great. all cylinders are firing. with the boat on water, and the engine running, i can lift the throttle linkage by hand and rev the engine up to 5000 rpms, but when in gear, and using the remote, it only runs about 2500. won't even plane the boat out. i think it could be a problem with the linkage. if the engine will run great in neutral, and even rev to 5000 manually, what could be the problem??? any ideas, comments? if it was a timing problem, it wouldn't rev to 5000 in neutral, right?

 

[ray21]

Re: loss of rpm at high end

^

 

[JB]

Re: loss of rpm at high end

Hello, Ray.<br /><br />What a multicylinder engine will do with no load tells you nothing about its ability to make power.<br /><br />Yours isn't making power. The most common cause is the loss of one or more cylinders.<br /><br />Do a search for loss of power at WOT or full throttle. You will probably get over a hundred hits, with detailed troubleshooting advice.<br /><br />Let us know what you find.<br /><br />Good luck.

 

[sandy]

Re: loss of rpm at high end

I had a similar problem with a Johnson 150. Ran great at low rpm's, but would'nt go past 2500 rmp.<br />A motor guru helped me while at the lake and problem solved. Story: I was cruising at 4500 and the horn went off, the boat dropped to 2500 so I stopped and cut the motor, completely confused. Started up again, ran perpect, but could'nt get past that 2500. Back at the ramp this guru of motors looked it over and startd picking hydrilla (grass) out of the water intake holes and from around my prop. When cleaned up it ran perfect. I never heard of anything like this, but it happened. You might check inside your water pump and whatever feeds it water. I only drive'm not fix them, but it's worth looking at. I'd like to know if this has happened to anyone else. Good luck.