RV Repair: auxiliary fuel pump on 1999 Bounder, fleetwood bounder, pressure relief valve

Question
1999 Fleetwood Bounder with Ford Triton V-10, 6.8

Is my fuel pump in the tank? If so, may I install an auxiliary electric pump in the gas line near the tank? Will
the OEM pump pass through the auxiliary pump even when the auxiliary pump is not turned on. If the OEM pump fails, will the auxiliary pump draw fuel from the tank through the OEM pump?  Do I need to be careful of fuel pressure from auxiliary pump and how do I find out what pressure is acceptable?

Answer
It is in the tank.  Not a bad job if the tank is empty.  

Is your pump dead?  Or is this a back up?  I would not route throught both pumps at same time.  I would have a parallel valving set up with one side valved in and the other out.  I am not sure if you can pull fuel through the dead pump.  The auxilary pump may come as a kit with a new suction tube.  That separate tube may not be a bad idea anyway.  You may be able to tap the tank at the purge canister valve.  Put in a tee here.  The fumes will go one way to the closed valve, and be forced to go the other way to the canister.  In the event you have to use the alternate pump, you open the valve and draw from the tee.

Auxilary pumps are tricky because the fuel pressure is so critical.  You need high pressure, like around 50psi to feed injectors.  You need to let the computer control the pump.  You may find a kit on line from a place like, Summit Racing.  Make sure the new pump can be wired to the key, like the orginal pump.  You dont want the pump over running the pressure relief valve.