1984 Johnson 40HP Power Problems

[jhoffman6]

Having problems with my 1984 Johnson 40HP outboard. Does not idle well, but as I increase throttle, it starts to run fine. Mid range it's good, but as I'm at WOT, it runs for awhile then dies out. One day it ran fine, next day it started acting up. This happened about 3 years ago and it was the coils. This go around, I mentioned this to the mechanic so he checked all electrical, including powerpack, coils, etc., and it all checks out ok. All cylinders have compression, and spark. If it didn't run good at mid-range, I would think it was a fuel problem, or am I wrong to assume this?

 

[OBJ]

Re: 1984 Johnson 40HP Power Problems

Hi jhoff.....<br /><br />When was the last time the carbs were overhauled? Could have some "junk" floating around in the bowls keeping the fuel from being picked up through the idle tube. As you open the throttle, you start coming over to the high speed jet. Maybe why it's OK tween' low end and high end.<br /><br />Also check around for air leaks and such. Lose fuel hose will give ya' headaches. If you have a primer solenoid, make sure the little red handle is running along the long axis of the solenoid. If the handle is turned up, it's dumping a little extra fuel in to the carb. Makes idle lousy.<br /><br />Same if yours is manual primed. Make sure the manual primer is closed after start up.<br /><br />If you have a service manual, go through the sync and link and ensure the throttle linkages are tight at the carbs.<br /><br />Keep us posted...thanks.

 

[jhoffman6]

Re: 1984 Johnson 40HP Power Problems

The guy working on my motor is going to check it out. He's skeptical that it's a carb/float bowl/jet issue because it happens at the same RPM. He replaced the powerpack and coils, motor runs fine in the shop. Takes it out on the water, and it runs fine until WOT. About 3 minutes into WOT it dies, like someone hit the kill switch. As soon as he hits the start button, it fires right up and runs smooth. He thinks it might be an airleak in the primer bulb in the fuel hose. He's checking this out also. Make sense?<br /><br />He seems to think that because it's at the same rpm spot, it's got to be an elctrical problem. Plus the motor did the same thing 3 years ago, and after replacing the coils, it ran fine, no problems at all.<br /><br />Obviously he AND I are scratching our heads on this one, hence the reason I'm going onto this website searching for help. Thanks for the reply.