1980 Johnson 140 stopped cold at WOT

[cwaldeck]

I recently brought this motor back to life after not having run in over 10 years. Anyways, I've run the boat four times now with the performance getting better on each run. The motor is on a 19'6" aquasport and had been pushing the boat at right about 42. This is with a four blade 13.25 x 19 prop with th motor trimmed all the way up. With the motor trimmed up so high I was worried about losing water pressure and overheating, but I had a steady stream coming out of the pee hole and over 15 psi on the gauge. Well after about 30 minutes on the water cruising, while at full throttle the motor just completely shut down. No overheat horn, no missing, no pistons etc blown, it just stopped dead. I tried starting it immediately after, but nothing. It is not seized. The strange thing is after I was towed in and brought the boat home I figured I would try and crank it for the heck of it. First try it cranked up perfectly. Now after my long and drawn out story what could have caused this? I figured power packs, but why would the motor start back up after cooling off. I was thinking potentially the heat triggers the packs to go out. Is this possible? Any help would be great because this has me stumped. And also I figured overheat would be ruled out since the horn did not blow and I don't believe the temperature switches kill the motor on overheat, just blow the horn. Is this correct or do they yell at you and shut the motor down?

Thanks.

 

[cwaldeck]

Re: 1980 Johnson 140 stopped cold at WOT

I also had a full tank of gas.

 

[shade788]

Re: 1980 Johnson 140 stopped cold at WOT

When you got the engine home what position was the engine in? All the way down or trimmed to the position you had it in the water at WOT?

 

[tashasdaddy]

Re: 1980 Johnson 140 stopped cold at WOT

had one do me the same way, start and run great, then just act like the key was turned off. power pack...heated up. here's the testing you can do. begins page 33 i believe. http://www.boatpartstore.com/page33.asp

 

[Kevin W]

Re: 1980 Johnson 140 stopped cold at WOT

did you check the kill switch? (if it has one)

I can recall spending countless hours troubleshooting an ignition problem that was an age weathered kill switch.
or possibly the ignition key switch.

 

[Chinewalker]

Re: 1980 Johnson 140 stopped cold at WOT

Highly unlikely, make that impossible, that both packs would go at the exact same time. More likely something in the key or kill switch as was suggested above.

- Scott

 

[cwaldeck]

Re: 1980 Johnson 140 stopped cold at WOT

Thanks for the replies. There is no kill switch on my motor but I will check the key switch, if I can't find anything there I'll start testing the power packs. I think I should relace the packs anyways since they are about 20 years old. And in response to shade, it was trimmed all the way down at home. But I also tried staring it trimmed down right after it cut out on the water.

Thanks again.

 

[Joe Reeves]

Re: 1980 Johnson 140 stopped cold at WOT

Your explanation indicates two possible causes. One being an intermittent ignition switch (shorting problem), or a failing stator.

To test the ignition switch.... remove the Black/Yellow wire from the back of the switch. Note that with this wire disconnected, it will be impossible to shut the engine down via the switch. If this cures the problem, replace the ignition switch.

The stator..... Look under the flywheel and inspect it visually. If there's a sticky substance dripping down from in upon the timer base and powerhead, replace the stator.

 

[cwaldeck]

Re: 1980 Johnson 140 stopped cold at WOT

Now that you metion a sticky substance it reminds me that the coils had a yellow colored sticky substance dipping off of them. I'll check the stator and the ignition switch and get back to you.

Thanks.