posted 05-05-2010 11:22 PM ET (US)        

Anyway, he and my neighbor were out fishing the other day and the motor started acting up such that when they matted the throttle to get up on plane and cruising, it died on them... and then flooded, so it wouldn't restart. (They didn't know at the time that it was flooded).

So they bring it over to me today so I can have a look at it. It starts and idles, though I found that I had to hold the link bar connecting the butterflies, (twin carbs), slightly cracked for a few minutes until it warmed up, then it idled ok, with only a slight stumble or miss.

As out on the lake, when I tried to rev it, using the fast idle lever, it stumbled and hesitated before it would clear, and then rev. If I left it spooled up, it would do a quick stumble, then die. Sometimes, if I brought the fast idle paddle down quickly enough, it wouldn't die.

If not for the wonky, wet plug issues, it almost acted as if there is some kind of "failsafe" intentionally cutting the motor, but I've never had one of my own motors be sick enough to activate a failsafe.

Stuff that may or may not be related:

This is one of those models that has one of those weird solenoid "chokes" that doesn't actuate a linkage, but has fuel lines hooked up to it and a red lever knob with a Schrader valve. There is a small fuel leak from the red plastic knob, where the Schrader valve goes into it. Also, the tip of the solenoid shaft is supposed to be a something that rides in a semi-circular groove on the shaft of the red knob... but that "something" is now gone. I can't tell if that is enough to cause erratic fueling issues.

No matter how long we idled her, the telltale water never got warm, though the stream was strong.

My prescription to him would change that solenoid thing and test/replace the thermostat. But he is down on his luck, with the economy like it is, and doesn't want to "throw parts at it"

I didn't do any testing of the spark, since it started and idled fine as long as the plugs weren't wet. I've never had to chase down a problem of "no spark at high rpm", so if that's a possibility, what would you do to test it?

-Peter

posted 05-05-2010 11:41 PM ET (US)            

Can anyone run me through the diagnostic "tree" for troubleshooting this hombre?

I'm thinking at the very least, maybe I could pinch off it's fuel supply with some Vise Grips and take it out of the loop, once the motor is running. If it runs right then, maybe the solenoid is the culprit?

posted 05-06-2010 01:05 AM ET (US)            

The valve can be operated electrically or manually. An electrical solenoid is wired to the remote start controls. Typically if you push in the ignition key switch, the solenoid is activated.

posted 05-06-2010 01:09 AM ET (US)            

If the manual fuel enrichment valve is inadvertently left open, the engine running characteristics will be affected. The fuel-air ratio will be too rich. The engine will not idle well, and it may stall out.

It is easy to inadvertently open the manual valve. I speak from experience.

posted 05-06-2010 01:17 AM ET (US)            

Thanks. I had read about that QuickStart system and those primer solenoids, but none of my motors have that system, so I never faced troubleshooting it and the knowledge atrophied. We had that primer solenoid fully counter-clockwise--er, that's the way I found it when it was brought to me. I'll get the boater with the stricken motor back over to my house tomorrow and try that and report back.

posted 05-06-2010 01:58 PM ET (US)            

BTW, the diaphragm and rotary valve and such are available separately for a few dollars in the event that those parts go bad, but the solenoid still works.