'97 Merc 50 HP Just Stops Running

[tablerockboater]

I'm just trying to get some ideas . . . maybe someone else has had this problem. That's stupid . . . of course someone, some time has had this problem.

Our '97 Merc 50 HP 2-stroke has always run just fine. But, now it just stops running without warning.

There does not seem to be any sort of pattern. We could run 10 minutes or we could run 60 minutes. It may stop running and it may not stop running. When it stops, it will get us to the least convenient place, far from our dock, and then just stop.

It seems to be getting gas, but no spark. It does not sputter, or run rough. When it stops, it stops all at once. It's got portable fuel tanks, a new fuel line and bulb, and the bulb pumps up firm.

If it sits awhile, sometimes it will re-start, and sometimes it will not. The last two days, for instance, it would not start, but today it started and ran just fine, so we put it on the trailer. Actually, today we used the tide current, and "poled" to the boat ramp, and were going to crank it onto the trailer, but then it started right up, so I was able to power it on.

Any thoughts?

 

[roscoe]

Wiring, loose connection or grounding out.

Could be in ignition switch, deadman's kill switch, stator, trigger, or a ground.

Gonna need to isolate each and troubleshoot.

Nothing beats a factory manual for such a task.

 

[tablerockboater]

Wiring, loose connection or grounding out.

Could be in ignition switch, deadman's kill switch, stator, trigger, or a ground.

Gonna need to isolate each and troubleshoot.

Nothing beats a factory manual for such a task.

Thanks for the reply.

A factory manual or our guy.

That's pretty much what he said, and what we looked at.

The stator has been replaced at some time. There were a couple of funky-looking "closed" pins on the pin connector. It's not the kill switch. It's got the original trigger box.

However, the trigger wiring harness looks suspect. So, we're going with replace that and clean up that pin connector.

Our guy says there's no way to test the box.

The main diagnosis problem is that it runs just fine until it doesn't, and that could be an hour.

Anyone want to talk about the towing lesson I learned?

 

[DavidMoore]

I have similar problems, but not with the engine.

Buying it flowers might help, works for me sometimes.

 

[tablerockboater]

My guy is going to replace the trigger and the box . . . that questionable wiring comes with it.

No flowers.

 

[tablerockboater]

I was just on the Mercury site and it said:

Mercury Marine recommends that the switchbox(s) be replaced in the event of a stator failure.
This is because a bad stator can weaken or ruin a good switchbox.

It is often the case that the old switchbox(s) fail shortly after a new stator has been installed.