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2000 Mercury 50HP Idle Issues When Warm/After Running

A

adambird

New member
Hi Everyone,
New to the forum here, your suggestions/feedback will beappreciated.
I have a 2000 Mercury 50HP carb version. When I first boughtit the motor ran rough around 2k rpm and would bog itself to quitting once in awhile. When I could get it through to the power band it ran smooth. Seafoamseemed to clear that problem up but included it in case it is pertinent to thecurrent issue.
The motor starts and idles perfectly when cold. I can runthe boat to the fishing grounds but quite often once I go to start it back upit won’t idle well or for very long. Sometimes it won’t even start. I’ll crankit over, sounds like it will run, but immediately falls on its face. In order to get itgoing I have to be ready on the throttle to rev it up otherwise it won’t go. Neverhappens when it is cold and is at its worst when it is hot outside and has beenoff for more than 15-20 mins. It does seem like the bulb isn’t holding pressureduring this scenario, should this be my first move?

Thanks in advance,

Adam
 
The bulb does not hold pressure after the motor has been cranking / running !-------There is nothing wrong with that.
 
It is possible that you have a break in the low speed stator windings.

When it's cold and the copper windings are contracted you have continuity and they produce power.

When they get warm/hot they expand and the (break) opens up causing the issue.

A break in the low speed side would not effect (significantly) the high speed side and those winding sound like they are providing enough power to keep things going above 3500 rpms (so doing their job) - the low speed side continues to provide power all the way up the rpm band to augment the high speed windings, but below 3500'ish rpms (it varies by model), the low speed are all on their own.

If the motor absolutely starts cold then you can test my theory with a hair dryer (or heat gun). On a cold motor take the (blower) and really heat up the flywheel - if she won't start once you have it warmed up that's a pretty good indicator that you need a new stator (and a "free test" is as good as it gets).
 
This motor should have CDM modules and stator don't work that way as it dont have a low or high speed...

When motor acts up check to see it carbs are flooding or sheen in water round engine, also check spark as a failing CDM module can cause the others to act goofy.
 
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Thanks for the replies guys. The boat is up for the winter but I'll be getting it back in action soon.

I'll try your ideas and let you know what I find. I have noticed sheen in the water around the engine sometimes...
 
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