Generator Fuel Filter

[dougm]

The Onan generator sits at a level above the fuel tank, the filter in the picture is 4 to 5 times the diameter of the fuel line. The little electric fuel pump
is not a high pressure high volume pump like the one that runs your truck engine. The pumps put out maybe 3 psi of pressure to feed the little carburator on the generator, any more than that and a simple needle and seat would not be able to stop the fuel from entering the float bowl. My thinking was that everytime i shut off the generator gravity would draw the fuel back out of the hose and the big filter. I began to wonder how much stress i was putting on the pump forcing it to overcome gravity as well as fill the extra volume inside the filter on the suction side of the pump versus it being on the pressure side of the pump. Not saying this is scientifically founded, just thoughts that made me decide to find a smaller inline filter. Also as a side note, the generator side of the fuel pump basket in your gas tank does not use a oneway check valve to prevent fuel from siphoning back into the tank. I have an old basket/pump stashed away, if i get some time maybe i will snap a picture.

[chin_k]

I see. My note on Onan's manual says the fuel pump is actually 3 feet lift, or 1.3 psi. The shut off is 3 psi. It may not be that bad to let the fuel drained down... make it less likely for it to gum up in the carburetor???? I never read anything on how far can you run the fuel line, so maybe the extra volume due to the filter is not as bad as you initial think.

Edit:
I see that the spec limit the fuel line to 15 feet, so I guess what I said above is wrong. If the large filter essentially make the fuel line equivalent to >15 feet of 1/2 ID hose, that it is not good.