MS250

PTmowerMech

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What am I missing?

New fuel. Cleaned out the fuel filter. Plug is wet & getting fire. Flywheel key is good. It's got plenty of compression (over 125lbs). I see no signs of a scored cylinder. Put in two new RCJ6Y's, and still nothing. So I put the original back in, and still nothing.

Yesterday, it ran fine. It idled pretty smooth. And WOT produced good RPM's and plenty of power.

Today, I got one little "almost start" and that was it. I've poured a little mix into the plug hole, after blowing it out, and got nothing.

Update: Removed plug sprayed a tiny squirt of carb cleaner in it, and still nothing. Rechecked the spark. and it's still good.
 
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Hammermechanicman

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Remove the spark plug. Disconnect fuel line from carb.Turn saw upside down with plug hole facing down. Pull rope vigorously about 30 times holding throttle wide open. Put clean dry plug in and connect fuel line. Try to start saw with choke on. AS SOON AS IT FIRES ANY AT ALL TAKE CHOKE OFF. Pulling the rope even one more time with the choke on will usually flood it.
 
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PTmowerMech

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Remove the spark plug. Disconnect fuel line from carb.Turn saw upside down with plug hole facing down. Pull rope vigorously about 30 times holding throttle wide open. Put clean dry plug in and connect fuel line. Try to start saw with choke on. AS SOON AS IT FIRES ANY AT ALL TAKE CHOKE OFF. Pulling the rope even one more time with the choke on will usually flood it.


Thanks man. That worked like a charm. The fuel that was spraying out of the plug hole, and then the muffler was shocking. What causes all that flooding? And how does one prevent it from happening. Since every time someone finishes using the saw, they turn them off, and store them until they need it again. Is there something special about this one?
Or did I do something wrong to start with? I always choke it til it tries to start. Then 1/2 choke and run it that way for a few seconds. The open the choke all the way by pulling the trigger.
 

StarTech

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Clean and rebuild carburetor is a starting point. Flooding usually caused by overly stiff metering diaphragm though I have had a couple carburetors where the needle seat was leaking and then it is a new carburetor. This is where a pressure tester is handy so you test before installing a kit.
 

Hammermechanicman

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Couple things can cause it but the most common is the saw stored somewhere hot the fuel tank pressurizes and fuel slowly leaks past the needle and it doesn't take much to flood the saw when the choke is used to try to start saw.
 

Fish

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That model seems to flood easily, moreso if the fuel starts getting old.
 
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