60 hp Johnson - Loss of power at high RPM

[2Win]

Hi Everyone,

New to the site here, but hoping someone can help solve my headache!

I took out my '87 Johnson VRO 60hp for the first time this spring and seems to run well at 2k-3.5k RPM, but dies once I get going at higher RPMs for a few minutes. It's happened a few times now, and the last time it happened the oil siren went off and when I started it back up it seemed to sneeze, which has not been a problem until now. The engine smoke is pretty cloudy and looks to be getting oil. The cylinders all have good compression and the spark plugs seem to be fine.

Does this sound like a lean oil problem even though it smokes cloudy? Could it be an air leak in my fuel line causing it to die? Should I try premixing my gas and see if that does the trick? Anyone have any solutions or ideas? Thanks!

 

[kenmyfam]

Re: 60 hp Johnson - Loss of power at high RPM

When was the last time you rebuilt the carbs ???

 

[kenmyfam]

Re: 60 hp Johnson - Loss of power at high RPM

Once again I forgot.....welcome to iboats

 

[2Win]

Re: 60 hp Johnson - Loss of power at high RPM

The middle piston was scored 2 years ago and we bored out that cylinder wall and rebuilt the carb. It's worked fine up till now. The other two carbs have never been rebuilt.

 

[HybridMX6]

Re: 60 hp Johnson - Loss of power at high RPM

If it runs ok for a few at higher rpm then dies, sounds like a fuel delivery problem. Is the tank vent open, how's the primer ball when this happens? If all of that is fine, then I'd suspect the fuel pump possibly? I wouldn't think just one carb being gunked would make the engine die, but it would make it run lean and cause another problem for that one cylinder. When it happens, try squeezing the primer bulb and see if it comes back or not. For some reason it sounds like the engine is sucking the bowls dry at high rpm's, which to me sounds like the problem is before the carbs. A good carb cleaning wouldn't hurt though.

 

[tashasdaddy]

Re: 60 hp Johnson - Loss of power at high RPM

i think you need to get terminology correct, you do not bore out carbs. you bore out cylinders. carbs are on the front of the motor, and mix the fuel and air, and feeds it to the cylinders, for combustion. i agree 99% carbs need cleaning, rebuilt, and adjusting.

also compression, and spark check.

 

[2Win]

Re: 60 hp Johnson - Loss of power at high RPM

Thanks for the replies.

Compression looks normal and also checked the spark and it seems fine.

Just wondering if I should try running it with someone adding pressure on the gas bulb to see if that cures it or just taking it in to clean the carbs and have the fuel pumped looked at first? Just don't want to push my luck too much.

 

[2Win]

Re: 60 hp Johnson - Loss of power at high RPM

Sorry, but I forgot to add that the tank vent is open, so that should not be the problem.

 

[tashasdaddy]

Re: 60 hp Johnson - Loss of power at high RPM

i would check compression and spark first, before you take it in. Read the TOP SECRET FILE.