posted 09-02-2012 11:03 PM ET (US)        

Both times I was unable to restart the motor for several minutes. When I tried, it would turn over totally normally, but not fire at all. I removed the cowl and had my son crank it while I pulled a spark plug wire and there was no spark. Primer bulb was firm and I was able to pump it harder and I could feel the fuel moving, so I'm reasonably certain it was a spark issue, not a fuel issue.

I thought it could be a problem with the ignition switch assembly, but even when the engine would crank over and not start, the engine would beep and the normal test lights would blink, so it seems to me that the correct electrical connections were making it back to the engine. I.e. that it's not a faulty switch or bad wiring from the switch to the motor. Note that on this motor, the kill switch is a physical device such that if the lanyard is pulled, the key is physically switched off. And once that happens you can usually restart the motor without replacing the lanyard. In my case, I tried removing and replacing the lanyard, but could not restart the motor.

A few minutes later, I cranked it again and it just started up as if nothing was wrong. The second time it happened was an exact repeat of the first, but by that time I was almost back to my mooring. After again waiting a few minutes, I was able to restart and get back.

After that, I spent about 30 minutes trying to reproduce the problem, but was unable to do so. The motor seemed to work just fine.

I'm going to have it serviced, but am very curious if anyone has any insights as to what may be wrong. Because the problem is difficult to reproduce, I am concerned that the shop won't be able to pin it down without some guidance!

Could a faulty distributor or coil cause this? Do they ever fail intermittently like this?

Thanks!

JTC

posted 09-03-2012 12:23 AM ET (US)            

For the engine to stop so suddenly would seem to imply sudden loss of spark ignition on all cylinders. This could be caused by;

--safety lanyard circuit

--failure of the main spark control unit, sometimes called a Power Pack on OMC engines;

posted 09-03-2012 07:47 AM ET (US)            

Do not overlook other items that can cause a sudden shutdown. One is the "kill wire" circuit that is designated by the black-yellow wires from the powerpack to the keyswitch. Especially in salt water environments, any short circuit to ground or even a slight resistance to a ground with stop the engine. This also includes the keyswitch and separate "kill switch" if equipped.

If yours is a 1996 or newer, a common problem was arcing between the black-yellow and a ground inside the 6 pin Deutsch connector for the engine harness and the boat harness. Many riggers did not pack both sides of the connector socket with dialectric grease as specified in a service bulletin and the high voltage in the "kill circuit" - above 400 at times - could arc to ground and stop the motor.

Remove both black-yellow and the black wires from both sides of the connector and inspect for any arc marks on the pins and sockets along with any carbon tracks inside the connector shells. Pack the socket with dialectric grease and then install the orange wedge allowing the grease to squeeze out. Use some on the rubber seal also for good water resistance.

posted 09-03-2012 11:05 AM ET (US)            

I'm pretty sure it is not the safety lanyard because the lanyard actually attaches to the keyswitch itself and when pulled it physically switches the key to off. I.e. there is no separate electrical circuit that is triggered by the lanyard.

seahorse: Just to clarify -- are you talking about inspecting the connectors on the key switch end. I did unplug and inspect all the wires where they plug directly into the back of the key switch and also the sealed connectors (there seemed to be two separate ones -- one with 2 wires and one with 4). Everything there appeared to be in excellent condition with no corrosion, tight connections and proper grease. I didn't inspect anything on the motor side of the wiring.