1977 Johnson 115 hp Idle Problem

[spiker_man]

Hi All. I have a 1977 Johnson 115 hp outboard. I'm having problems going from idle speed to flooring it (i.e., like trying to pull a wakeboarder out of the water). The engine stalls out if I quickly advance the throttle. Doesn't happen all the time . . . but it happens enough lately that I'm going to need to have it looked at. At times I can slowly start moving forward and then throw the throttle forward to start moving faster. Any clues on what I should be looking for? I'd like to appear somewhat knowledgeable when I go to the mechanic and he asks what's wrong . . . I'm thinking that the carb may need a good cleaning or rebuild. Am I on the right track or am I far off base? Any advice would be greatly appreciated. Thanks. Paul

 

[iwombat]

Re: 1977 Johnson 115 hp Idle Problem

I think you're probably right on target. It could also be dropping spark in one cylinder. Are you getting up to full throttle eventually?

 

[spiker_man]

Re: 1977 Johnson 115 hp Idle Problem

Thanks for the reply. Yes,I do get up to full throttle. I have noticed that the spark plugs do seem to get fouled up (oily) fairly quickly. I bought this boat used and have only had it for a couple of years so I don't know if this is normal for this engine. I put new plugs in at the start of the season . . . only used the boat 5-6 times this summer and last month when I looked at the plugs they were pretty dirty. I'm going to be taking it out again this weekend and am planning on putting in new plugs to see what happens.

 

[iwombat]

Re: 1977 Johnson 115 hp Idle Problem

When's the last time it was decarbed?

 

[spiker_man]

Re: 1977 Johnson 115 hp Idle Problem

Not sure. I've had the boat for only 2 years. I did pour a can of carb cleaner in the gas tank back in August when I last filled up the tank. I don't know if anyone ever decarbed the engine prior to my purchasing the boat. Thanks.

 

[iwombat]

Re: 1977 Johnson 115 hp Idle Problem

I'd start out with a proper decarb. You're way over due. Check out the FAQ for the procedures. Anything else you do, won't matter much if you've got a carbon problem trumping it all.

 

[spiker_man]

Re: 1977 Johnson 115 hp Idle Problem

Thanks iwombat. I'll be doing the decarb this weekend.