1989 Johnson 120hp - bogging down

[stets]

I just bought a 1989 120hp Johnson.
When I picked it up I checked the compression and all 4 cylinders were 145psi
It ran great for the first 2 hours, and then it started bogging down and not going over 2000rpm. I know it has been sitting for awhile, is it bad gas or plugs or carbs?

Any ideas?

Thanks

Mike

 

[ezeke]

Re: 1989 Johnson 120hp - bogging down

It may be overheating. The engine has a system in the powerpack called S.L.O.W. that cuts out half the cylinders when the engine gets too hot.

If the motor is new to you, you may want to treat it as one that has been in storage: http://forums.iboats.com/showthread.php?t=158086

 

[stets]

Re: 1989 Johnson 120hp - bogging down

Thanks, thats what I plan on doing.

As for the overheating issue, it does it when I fire it up cold.
When it is idling, it also sputers every now and again.
When I try to give it full throttle, it bogs and then stalls.

 

[crb478]

Re: 1989 Johnson 120hp - bogging down

If you have a protable gas tank hook it up with fresh fuel. That way you will know if this is a fuel issue or some other issue. Do you have a water separating filter?

 

[Dhadley]

Re: 1989 Johnson 120hp - bogging down

Sounds like the carbs need a bath. Remember, on that motor if a carb is plugged that cylinder is not only not getting fuel, it's not getting oil. Pistons need oil to survive.

 

[stets]

Re: 1989 Johnson 120hp - bogging down

I just had it out and while going full throttle and it bogging down, I pushed in the key choke several times and the rpms went up to normal, and stayed there as long as I kept pushing in the choke. Carbs??

 

[tashasdaddy]

Re: 1989 Johnson 120hp - bogging down

as said above, fuel starvation, it is not a choke, it is a primer, that squirts fuel directly into the intake, the motor is not getting enough fuel thru the carbs. time to clean and use rebuild kits. this is a good way to ruin your motor, fix it now.

 

[stets]

Re: 1989 Johnson 120hp - bogging down

Will do. Thanks for the advice.