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During the 70's and 80's GM made several changes to the dual fuel tank setup. Early versions had the 3 port fuel tank selector valve and mechanical engine pump only. These were subject to vapor lock problems.
Early 80's they added a frame mounted rear electric boost pump. By mid 80's they had evolved to a 6 port valve with intank electric pumps and fuel return lines.
Here is one from an old thread on Jim and Tere's coach.
I have replaced 2 of these valves, GM 467513. They were one wire solenoid type valves. With no power applied, the spring pushes the plunger to one end and opens the ports to tank 1. With power to the terminal, the solenoid magnet pulls the plunger to the other end to open ports to tank 2.
2 problems: the valve fails quickly and they are no longer available. I suspect that ethanol may have swelled the orings and made the valve stick. These valves originally date back to pre alcohol fuels. Both of mine eventually failed to transfer and ended up stuck, with fuel flowing to/from either tank.
There is a similar valve widely used in modern applications. Standard FV5 has the same mounting flange and fuel hose layout as the old GM version. This valve is motor driven to force the plunger in either direction reliably.
GM 467513 left------------------Standard FV5 right.
Unfortunately, the motor requires 2 wires to operate and the polarity of the wires is reversed to transfer the valve. (It also has 3 other wires used to switch power to the appropriate intank electric fuel pump, if needed)
Physical installation is easy. New valve bolts into same holes as old one. Fuel lines attach to the same valve ports, no trimming/fitting needed. Electrical requires some more work…
The original valve defaults to tank one and only gets power when tank 2 is selected. New valve needs two wires with constant power, but they must be reversed to transfer the valve. 2 options: install a double pole single throw switch in the dash panel and run a second control wire all the way back to the valve.
Or, mount a double pole relay near the valve. Feed power and ground from the nearby fuel pump (energized whenever the fuel pump is running) to the relay. Trigger the relay with the existing selector wire. When the relay is not energized, the power wires go to the valve and select tank one. When the relay is energized the wires to the valve are reversed and tank 2 is selected.
If you are replacing the old valve with a new one, you will need the harness to fit the plug. Order FV5K (the kit contains the harness plug and DPST switch.)
Before: (so that's where that hose clamp went…)
I epoxied the relay to the side of the valve.
86 Regal SE 33 Tag axle--"98" Monarch 37
Chev P3(7) 454TBI--------Cummins 8.3 300 hp
400 hp fuel injected-------6 spd Allison, Spartan MM
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