1995 Merc 60 won't exceed 3100 RPM under load

[Gene Neill]

This problem happened all at once. One minute it ran great, the next minute not. Engine starts perfect, idles perfect, runs perfect up to 3100RPM, and will redline in neutral. But it will go no higher than 3100 in gear. Carbs are clean, fuel is new, plugs are new and clean, spark is strong. No cylinder performs differently than any other. Compression checks out. Very low hours on the motor. Local shop with fabulous reviews went through it, adjusted the timing a little, said it ran great. LOL

Any suggestions before I look for another shop?

 

[racerone]

Checked flywheel key ?---Reed valves checked ?------All carburetors opening up ?---Cylinder sleeves rotated ?-----Carbon blockage in exhaust housing ?-----Run with a timing light one cylinder at a time ( on the lake ) and see if you lose spark on a cylinder.-----Water pump maintained ?-----New impeller installed every 5 years ?----Post compression values taken today.

 

[QBhoy]

Did it run better previously and with the same prop as it has now ?

 

[Willyclay]

...and will redline in neutral.

You probably should not do this again. Good luck!

 

[Scott Danforth]

This problem happened all at once. One minute it ran great, the next minute not. Engine starts perfect, idles perfect, runs perfect up to 3100RPM, and will redline in neutral.

you only need 2 drops of fuel and one cylinder to get a motor to rev in neutral. that doesnt mean anything other than you may wreck your motor running it over 1500 RPM in neutal

This problem happened all at once. One minute it ran great, the next minute not....Carbs are clean, fuel is new, plugs are new and clean, spark is strong. No cylinder performs differently than any other. Compression checks out.

How do you know the carbs are clean?
does the spark jump 1/2" on a spark tester?
post the compression numbers here. saying compression checks out doesnt mean anything. real numbers on a known good gauge and you compare them to the factory specs.

did you check fuel pressure?
did you rule out the boat side of the fuel system by running on a different tank?

Local shop with fabulous reviews went through it, adjusted the timing a little, said it ran great. LOL

take it back to the shop. have them do a seatrial

 

[Gene Neill]

So I took the boat back to the mechanic. This time he replaced the stator, which made the motor actually run WORSE somehow.

Took it back AGAIN (third time's the charm?) and he said oops, it needs a new power pack along with that stator.

Financially, I kinda feel like a sorority girl who woke up on the frat house lawn with her panties missing. BUT ... the motor runs great again.

Thanks for all the replies, much appreciated!