When I was being educated in hydraulic systems the following was pounded into my head, "It is easier to control 1000 PSI (68 BAR) than a vacuum". With this in mind a low pressure ULSD/Biodiesel electric lift pump would be a sensible addition. This would also help keep out the air bubbles, and give us slow damp leaks we can repair. The DOT regulations will require the addition of a circuit to shut down the electric fuel pump in the event of the engine stops running. This would only become a factor in the event that one of us gets into a crash and burn accident and the Insurance Company would take the opportunity to wash their hands and not pay up. What GM did with the old VEGA was use a Normally Open (NC) oil pressure switch that turned off the electric fuel pump when the engine quit running. Other manufactures have come up with excessively complicated fuel pump relays that were designed by ad hock teams with each member having their own agenda.
We will need to factor in the following before installing any electric lift pumps:
1) Fuel pump control circuit to activate the pump before starting and shut off when the engine quits running for any reason. Opinion: Jeep who tends to be smarter than the rest of DC may have something in the fuse box already. My Liberty has the always live 12V power port, something lacking in most of the rest of the DC line up.
2) A low pressure external electric fuel pump (4-7 PSI) that is ULSD/Biodiesel compatible (not all are).
Comment: The gas Liberty fuel pump is designed to have high enough pressure to run the fuel injection system, this could screw up our injection systems.
3) A reliable low pressure external electric fuel pump that is better quality than the local discount auto parts store, perhaps marine grade.
I have had to many of the cheap ones fail on the old British Sports Cars of the 60s & 70s.
4) The closer we can get the low pressure electric fuel pump to the tank, the less likely we are to suck in air when the hoses get old and the clamps loose compression against the hose placed onto the barbed fittings.
Steve
Here's the Guy's to do it:
http://www.mwfi.com/fass/fass.html 