Logo

120 Force Lost Top Speed But Not RPM

R

Ron Schuller

Guest
" I was in rough water over th

" I was in rough water over the weekend and was heading back to the landing when I noticed my top end speed had dropped about 10 mph. RPM was still the same. I tried adjusting the trim because of the rough water, but that didn't help. I was thinking spark plugs and I talked myself out of that thinking my RPM would have gone down. Same thought pattern for fuel pump. The engine didn't seem starved for gas. Please help! "
 
" Rough water is going to do a

" Rough water is going to do all sorts of things; your prop may be coming out of the water, the boat might be fighting wind and/or current and must plow through chop. If you are using a non-gps speedometer, one that actually uses the water, it's not going to work right either, as it will not have constant water contact (they never work accurately anyhow).

If you take it out in calm water, and something still seems to be wrong - your prop's hub may be slipping or damaged. To check for slippage, you can either mark the prop nut/prop and see if it changes or use a 2X4 between the prop, trim tab, and lower unit to lock the prop, put the engine in forward (NOT running) and attempt to turn the flywheel nut (clockwise). If the flywheel turns without the prop, your prop hub is damaged.

Jon "
 
" Rough water will slow your e

" Rough water will slow your engine down. I was worried about mine this spring. Mine's a 15HP Johnson, and we were out in the gulf when it got rough, and even at WOT, we weren't going much over 10MPH. Tried it in calm water a few days later and no problems. I don't think you ahve to worry unless this problem persists. "
 
Thanks for all your help. I&

Thanks for all your help. I'm going out this weekend and will be crossing my fingers.
 
" Went out Sunday and she ran

" Went out Sunday and she ran fine. Much better conditions; although, the fishing was tough. "
 
Back
Top