I have a hand crank fueler i was fueling my plane and everything was fine at the end of the day i was going to de fuel the excess fuel and i could not get the fuel to out of the tank. I cranked in the opposite direction to fuel the plane and the fuel flows fine into the tank i start cranking backwards and all i get is air no fuel going out of the plane. I thought it might be my fuel tank set up so i changed all the lines and still the same problem. Today i tried a different plane and the same thing happens i can put fuel in but i cant take fuel out. If anyone has any suggestions please let me know. One of the engines is an O.S. 46 AX the other is a Saito .72.


Thanks

Sounds like you have either teed into the carb feed line and when trying to empty the tank you are pulling air thru the carb. If this is the case sometimes closing the carb by hand or with the throttle stick and full close trim then shutting off the receiver will close the carb enough to allow you to empty the tank. If any air leaks past the needle valve it will suck air instead of emptying the tank. You can buy a fueling valve that blocks this port when the fueling nipple is inserted for fueling or defueling the plane.

If your using a third line you have to use a clunk to make sure when defueling you are removing the fuel from the lowest part of the tank if you only have the third line inside the cap with no clunk it will only remove fuel to the level of the end of the fuel line

I have a 3 line tank on both planes and i have a clink on both . I had a few nitro planes before this and never had this problem.

Try pumping with your finger over the airplane
end of the fuel line. If you get fuel coming out
somewhere it shouldn't, that will also be where
you are getting the air that it pumps going the
other direction.

Jenny

Sounds like you may have an air leak/pinhole. Is it in the fueling system (it sounds like it might be because both models suffer the same conditions). Check the pump and lines by attaching a short length of fuel tubing to the end of your fill line and pump a small container with fuel. Keep the end of the added fuel line submerged and try emptying it. If you see air bubbles try and find out where they are forming. It could be a split fuel line on your pump or could be the pump itself. If you can fill and empty no problem then you have a split or leak somewhere on the airplanes fuel system. If the engine runs through a full tank no problem I would suspect the split is in the fill empty hose inside the tank.

Dennis

If your fuel line is old the inner walls could be softening and collapsing.