OS 120 lll Pump

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05-24-2011, 03:57 PM

MX240

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OS 120 lll Pump

I have a OS 120 with a pump. Has been running good. Now RPM varies in the air...not the kind of too rich or lean rumming.
I changed plugs with no help.
What starts to happen when the pump wears out?
Jim

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05-25-2011, 06:00 AM

Bax

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RE: OS 120 lll Pump

Usually, the pump doesn't wear out. It can become contaminated and have passages blocked by trash in the fuel. Also, the regulator can have its ports blocked by trash, too. Erratic running can usually be traced to the fuel system or by tuning. If it's too rich, the engine can surge.