I have a ’97 Merc 25hp that starts great and runs fine except that it seems to have lost some of the top end speed / rpm. I would guess I’m getting maybe 75% of the performance it had. I have new plugs in it and the fuel strainer/basket seemed clean. Ran some SeaFoam through it with the gas – no improvement. Would a leak in the fuel hose be a possibility – messing up the mixture? Any ideas would be greatly appreciated. Thanks!
How is the prop, is the bottom of the boat clean…these can rob top end.
The bottom of the boat is in good shape and the prop has a few small nicks but nothing major. I do have spare prop I could try.
Thanks for the reply.
You may want to have a compression test done. That alone can tell you a lot about the condition of the motor. Quick and easily done at a dealer or you can get the guage at Fleet Farm or Northern.
-J.
I’ll give that a try – thanks for the input Jon.
A 25% loss is significant. A compression check is easy and cheap. If you have a bad cylendar/heads/rings the compression check should show it. If you have good compression, then it;s on to the other 3. Gas, Spark, Air.
-J.
If the compression checks out I’d look to your timing being way out of wack or your high speed jet in your carb being partially plugged.
Thanks for the suggestions guys. I’ll start with a comp.check and go from there. It runs very smooth with good acceleration – no missing or hesitation, just has lost some of its muscle on the top end.
Thanks again for the input!
Steve
You must be logged in to reply to this topic.
