1987 Johnson 40 hp Vro

[Hydmaster75]

Ok boat has been sitting up for about three years cleaned carbs changed plugs and motor was running fine in the yard. Took it out to the lake and while running down the lake heard a grinding sound and engine quit. Pulled cover off and it looked like the starter was engaging the flywheel but I was not turning the key. Tried to start engine and it fired right up but a few mins later same noise and engine quit. Brought it back home and cleaned gear on starter but still having same problem. When the boat is in the yard doesn't sound like the grinding sound is coming from the starter making contact with the fly wheel. Verified that it is not but can't figure out what is grinding and stoping the engine. Please help! Sorry so long

 

[Joe Reeves]

Re: 1987 Johnson 40 hp Vro

A shorted starter solenoid will cause the electric starter bendix gear to stay engaged in the flywheel ring gear.

Remove the spark plugs to inspect for foreign material.

Drain a small amount of gearlube to inspect for metal.

(Starter Solenoid Sticking)
(J. Reeves)

Sooner or later a boater will encounter a situation wherethe key is released from the START to the RUN position, or to the OFF position and the boater suddenly realizes that the electric starter is still running. This is due to having the starter solenoid sticking in the closed (contact) position. Sometimes a whack to the solenoid will unstick it temporarily but usually it's necessary to remove the cable from the battery.

The cause? A weak battery or even a top notch battery that is running low in power causes a arcing within the solenoid that eventually welds the two opposing large terminals together.... the two opposing terminals being the large incoming positive battery solenoid terminal connection and the large terminal leading from the solenoid to the starter. The return spring with ther solenoid simply isn't strong enough to break that weld resulting in the continued flow of voltage to the starter.

The cure? If the battery is flawed, get rid of it and purchase a top notch battery. And also...... Replace the solenoid. Don't play with it, trusting that it won't happen again because it absolutely will, and that happening is usually in the worse possible scenario.