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120 surpass pump problems

Old 04-06-2005, 03:54 PM
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Default 120 surpass pump problems

Bill,

My 120 Surpass pump is not working up to par. It pumps fine when the engine is level, but when I point the nose up it ceases to draw fuel. I suspect a hole in the diaphram. As it is the old original 120 surpass with the brass screw in the center of the pump, are parts available for the pump and can it be repaired? My understanding is that the pump or parts for the pump are no longer available. If this is true, can the pump be replaced with a newer version?

Regards,
Dave Farren
Old 04-07-2005, 09:46 AM
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Default RE: 120 surpass pump problems

The O.S. FS-120 Surpass I, with the brass screw in the center of the pump does not have a diaphragm pump. It's a geared pump driven directly by the crankshaft. If the attitude of the aircraft affects the running, then we'd look to the fuel system--tank and plumbing--first. It's possible that the pump's not working correctly. You can increase fuel pressure a bit if you turn the screw a hair clockwise. More than 1/4 turn tells you the pump is bad.

Unfortunately, that pump is no longer available nor able to be serviced. Even the pump for the FS-120 Surpass II is no longer available, since it's been out of production for nearly a decade.
Old 04-07-2005, 10:15 AM
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Default RE: 120 surpass pump problems

I have checked the plumbing from the tank and all seems well. I'll try turning up the pressue a bit. If, in fact, the pump is bad, is there anyway I can by-pass it and use the engine as an un-pumped 4 stroke engine? It is a really strong engine and I hate to lose it.

Thanks,
Dave Farren
Old 04-07-2005, 02:40 PM
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Default RE: 120 surpass pump problems

The carburetor of the FS-120 Surpass has a too-large bore to be used without the pump. You'd have to use a pressure system that also regulates the fuel flow to the carb as it demands fuel. The O.S. pump system had the regulator in the pump (in the FS-120 S-II).
Old 11-16-2005, 12:13 PM
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Default RE: 120 surpass pump problems

I have always been a devoted 2 stroke flyer. I recently purchased a used FS 120 Surpass I engine at[] an auction. Having never used a 4 stroke engine or for that matter a pumped engine, I am totally confused. Where do all these line from the pump go to? The pump has markings for; in, out and r. What the heck is r? Is there an old manual for this engine I can download? Thanks to anyone for the help.

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