F750 with a C7/3126 engine probs ..

[cbigham]

Hello all -
I have a F750 with a fuel tank problem. It draws from the passenger side to the engine, and the left side is supposed to transfer to the passenger side. Often it draws almost all the way down on the passenger side and I don't want to run it out of fuel. Any idea what causes this? My guess is something to do with a float sensor in the passenger tank. Seems to happen (tho not sure) when I really fill that passenger tank. Is there a bypass?

thanks

[tmodz]

The fuel tanks have 1 fuel sender for each tank, but only one controls the fuel gauge. The other controls the fuel transfer pump. Usually the left tank stays full and the right tank empties. The fuel transfer pump is located above the right side fuel tank. The most likely cause is the fuel pump is burnt out, the other likely casue is the left side fuel tank sender is inop.. The way to test it is to create a 10 gallon difference in the left tank, and with the engine running check to see if the transfer pump is running. And there is no bypass.