After fighting the fuel system for a few weeks, I realized that the problem was the aftermarket solenoid-style fuel pumps. Because they didn't allow fuel to bleed back into the tanks (like the original impeller-style pumps), the DFR was unable to switch, and it would jam midway, blocking all fuel flow.

Since aftermarket low-pressure impeller pumps cost ~2x as much as solenoids, and we already had new solenoids, I replaced the DFR with these valves from NAPA, and a SFR. There have been no fuel problems since.

The solenoids are carefully plumbed so that, when UNpowered, they default to the same tank. Wiring then is simple: they're parallel to the OTHER tank's pump, meaning, when the pump for the other tank runs, the valves are energized & direct fuel to & from the other tank.

Even though this section is strictly for low-pressure fuel, I still chose to use EFI-rated fuel hose.

For more info, see this album:


...but these have now been replaced with a 6-port valve designed for EFIs:

Owner caption May 2009 · Photo 315 of 689