RV Repair: Onan 5500 fuel supply, fleetwood bounder, main tank

Question
Bill,
I have a 1998 33' Fleetwood Bounder on a Chevy platform.  The fuel pump will not draw fuel from the main tank.  (the tank is full)  It will however draw fuel from a small container if I place it directly below the Onan. I need to determine if I have a fuel pump with low vacuum draw, or a leak in the long metal supply line from the tank.  I can not see or reach the top of the tank where the fuel line enters.  What is the spec for the pump draw?  How do I isolate the real problem?

Answer
Hi David:
The fuel pump will draw about 10 feet high from a tank. If it draws it up from the floor it should draw from the tank. Once the fuel gets to the pump it will gravity flow to the pump level because that is lower than the tank. Sounds to me like you have a small hole in the supply line and do not generate sufficient vacuum to start the flow going. It is a lot of work but you may have to change the fuel line to the generator by dropping the tank. You could try splicing into the main engine fuel line. The danger with that is that you could run the tank out with the generator and be stuck!
Bill