I have a '150 with the dual tanks. If I switch to my saddle tank, after about 5 miles of driving it will get sluggish and "feel" like it is running out of gas. I filled my aft tank full and switched to my saddle tank to run it empty so I could drop the tank and replace the fuel pump.( I am assuming it is in the tank). Anyways, after driving a significant amount of time on the "almost empty" saddle tank, I noticed it would never go to the E. I switched over tanks and realized that I was a half tank down on my rear tank. .......Is the saddle tank siphoning fuel somehow??? Is my saddle tank fuel pump bad?? is this all related to the valve that switches between tanks. Why cant I fiind the part number for this gas tank valve anywhere??

 

sounds like the fuel pump to me. one thing that i have noticed with duel tanks, If both start off full and I run the front tank all the way down (I know it has to be all the wasy down because of mileage) Then I switch to the rear run it down. If I go back to the front is has between 1/4 and 1/2 a tank of gas!!!!!! I think the lines are combined somewhere and just a little bit of fuel slips back into the tank that is not being used.