'86 Johnson 40 motor cutting out

[ste.fowler]

I recently bought a new boat with an '86 Johnson 40 engine. It ran fine for about a week. Since then it has started failing. It will run to begin with and then at high revs, revs gradually slow until it cuts out. It will restart fine on the choke, but then when you try to engage gear it just cuts out again and I have to get towed back to dock. Replaced the fuel filter this am but that did not fix the problem. Any suggestions. On the controls there is a friction throttle (dont know what this does) which I have not touched but could it be to do with that? also how do I know if the fuel tank is vented or not?

 

[fireman57]

Re: '86 Johnson 40 motor cutting out

sounds like you are running out of gas. Make sure that your gas tank is vented. When it does this is the primer ball sucked flat? If not you need to check spark when this happens with a buddy and a timing light. could be a coil breaking down when it gets hot. If you have spark, the tank is vented, then it sounds like carb rebuild/clean time.

 

[ste.fowler]

Re: '86 Johnson 40 motor cutting out

Hey, thanks for advice, when this happens the primer ball feels normal like its full of gas but not sure if the tank is vented or not. I'll investigate it to see if I can find out although I don't see any evidence of a vent at first glance.

 

[ste.fowler]

Re: '86 Johnson 40 motor cutting out

Hey, thanks for advice, when this happens the primer ball feels normal like its full of gas but not sure if the tank is vented or not. I'll investigate it to see if I can find out although I don't see any evidence of a vent at first glance.

OK, loosening the gas filler cap is the equivalent of venting right? Will test it tomorrow like this.