Force 90 Idles Great but No Power at WOT and only 2100 RPM

[snowbrd84]

I decided to give my Force 90 one more chance before getting a new engine. Last year after buying the boat, it would only do 4000RPM at wide open throttle and it absolutely DRINKS gas... I replaced the fuel pump diaphragm, cleaned out the carbs and did the carb sync and took it out on saturday. Started right up and idled great. Took it out on the water and gave it full throttle, and it maxed at 2100 RPM.

I verified the tach reading with a light tach i have. Compression on cylinders is 127-132psi. Butterflys open perfectly level on all three carbs at WOT.

Prop is 13-1/4 diameter 17 pitch. Same prop I used at the end of last year when i got 4000 RPM... I did adjust the screws on the carbs per the sync procedure as well.

I am about to give up on this motor, but it idles great and has good compression... Spark plugs only have a few hours on them from last year. I pulled them yesterday and noticed that there was a lot of RTV from when i replaced the head gasket last year, so maybe they werent grounding very well... So i got the dremel out and a wire wheel and cleaned the surfaces real good. Anyone have any ideas why this thing would only get 2100 RPM at WOT? Maybe one cylinder wasnt firing? Also, it wouldnt restart after i shut it off, it was flooded, I had to drain the carbs to get it to restart. The carbs do not leak at all, not a drop, if i pump up the bulb, it build pressure and does not release....

 

[snowbrd84]

Re: Force 90 Idles Great but No Power at WOT and only 2100 RPM

Also, fuel lines are brand new and its running off of gas cans. So there is no restriction in fuel flow.

 

[DAN M VAGOS]

Re: Force 90 Idles Great but No Power at WOT and only 2100 RPM

Go get yourself some cheap spark plug testers and run it in water and you will see if one or more cyls are cutting out. I would think if you have fuel and psi the only thing left is spark.