1991 60hp Johnson Bog down under load

[renvette2]

I have a 91 60hp Johnson 3 cylinder that bogs down on the water. It will get up to about 20 mph and shakes violently if I try to push it further. It runs great when out of the water with portable water tank. It appears to have trouble pushing the boat. Compression on all 3 cylinders was between 89-92. Any help or ideas are greatly appreciated.

 

[racerone]

It only sounds good to you running in a tank..----------Your motor is not in good shape and is not able to do the proper amount of work.---Check spark on all 3 leads.----To me it sounds like it is running on 2 cylinders.----Does the primer bulb go hard when you operate it...----Is oil injection system in service and working properly ?--Waterpump working properly ?

 

[renvette2]

Yes, the primer bulb goes hard. The oil injection was disconnected years ago and I mix oil and gas now. Water pump works also. I have a basic spark tester, will that do? Do I remove other plugs when testing one cylinder?

 

[WernerF]

Does the motor idle well in the water in gear?

 

[renvette2]

Yes, it idles well in the water in gear, but when I go forward it accelerates fines until I hit around 20mph and it shakes violently and will not accelerate. Then it dies out.

 

[racerone]

Test compression and test spark.----Post your results.---Check gear oil too.

 

[James R]

Don't rule out a bad lower unit.

 

[renvette2]

Compression on all 3 cylinders were 87 - 90 range
spark was good on all 3 cylinders

I'll check the lower unit oil in the morning. Do you mean lower unit oil when you say 'gear oil'? Thanks to both of you for your suggestions.

 

[renvette2]

Lower unit oil was quite dirty. Could this cause the lack of acceleration and shaking?

 

[racerone]

The term " good spark " means little.----Does spark jump a gap of 7/16" in open air, yes or no ?--If your compression gauge is accurate then your motor needs work !-I would pull the cylinder head to have a look in there.

 

[renvette2]

Yes, spark does jump 7/16" in open air. Do you think compression is my problem?