Can anyone tell me the exact way to set up the fuel tank connections on a pumped O.S. Surpass engine? I know one line goes to the pump from the tank, one line goes from pump to the carb, and the other line from the pump goes back to the tank. My question mainly is do I need to have a third line open for the vent at the top of the tank; and how should it be set up so I can pull the left over fuel back out of the tank. Will I need to install a re-fueling valve between the tank and the input to the pump. I have never used a pumped engine and I bought it used, with no instructions.

Red Max:

Here is a link to OS manuals. It may help


http://www.osengines.com/manuals/index.html

Are you asking about an after market pump like a Perry pump or are you asking about an OS with a built in pump. I have both but i am confused with your question. On my OS 91 with a built in pump, one fuel line comes from the 1st clunk in the fuel tank to the pump. Another line comes from the 2nd fuel tank clunk to my fuel/unfuel line that I leave plugged and a third line comes from the fuel tank vent and vents to the atmosphere, unpluged.

The pump on this engine is mounted on the back plate. It came with the engine. It is an O.S. 1.20 Surpass. The pump is round in shape and is bolted to the back plate. It has an "in" nipple, and "out" nipple, and a third one that I believe goes back to the tank.

IT's like my 91. facing the back of the engine and looking at the round plate, there are two nipples pointing up at 10 o'clock, the left one goes up about 1 inch and plugs into the regulator (triangular shaped). the right one goes to the fuel tank. there is a third nipple on the round piece facing towards the engine, it plugs straight ahead into the back of the engine. There is also a nipple on the intake tube on the back of the engine, a line goes from this around the right and towards the front of the engine and plugs into the crank case.

Your engine has a different type of pump. There is no triangular shaped regulator. The carb is a C12. One nipple on the pump labeled "out" does point up and goes to the carb. The other two nipples are regular fuel line type nipples, screwed straight into the pump, one is labeled "in" and the other is labeled "R" , which I assume is a return line to the tank. There is a brass screw right in the middle of the pump with a screwdriver slot and a small round hole in the middle of the slot.

I went to the OS site and there is a drawing showing the fuel pump as I had described it, only one line goes to the tank. I suggest you also go to their site and check it out. Click on the text below and it will take you to the OS site, scroll down to the FS-120-S III and select it.

http://www.osengines.com/manuals/index.html