I was reading up on the fuel selector valve setup this evening while trying to troubleshoot why the instrument cluster fuel gauge selector switch does not work on my 75 F350 CC. I pulled a fuel selector valve off a 78 F250 in the junkyard a few weeks ago and swapped it out for the one that was on my truck. Still no luck after swapping the under cab mounted fuel selector valve and simply re-seating the dash electrical connection.

PO had installed a manual style valve that I just wasn't crazy about. It was installed crooked, stops in 4 spots, but only has labels in 3 corners.



Tonight while looking at my truck after doing some reading I turned the key and heard the magical noise of a solenoid clicking! Sure enough the solenoid is clicking on/off as I turn the key on/off and when I flip the instrument cluster fuel gauge selector switch between main and Aux. The fuel gauge is not picking up the fuel level for the main tank, but that's not a big worry. The wiring on the main tank sending unit is corroded and loose so it'll probably start working when I clean that all up. I'm happy that I am able to use the dash switch and no longer need the manual valve. Sort of... now I just need to clean out the clogged main line/tank. When I put a new inline fuel filter on a few weeks back, the inline filter from PO had a fine collection of red desert dust in it. I bypassed the main line and directly hooked up the Aux. line.

Once I clean out the main line I can hook up both lines to the fuel selector valve. Main and Aux lines each have their own clear inline filter so I can see if any more problems are to be expected.

Just had to share my little triumph

 

1973/74 F100/350's with dual tanks came with D2TZ-9189-A .. Manually Operated Fuel Tank Selector Valve. Located on the floor adjacent to the drivers side of the seat.

The switch (D3TZ-9A050-A) only changes the dash fuel gauge from one tank to the other.
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1975/79 F100/350's with dual tanks came with: D5TZ-9189-B .. Fuel Tank Selector Valve & Solenoid Assy. Located on frame rail.

The switch (D5TZ-9A050-A) changes the tanks and the fuel gauge.

1973/79 F100/350 with factory installed dual fuel tanks: The switch is located in the heater control panel.

D1AZ-9A011-A .. Plastic Mesh Filter Screen-3/8" I.D. / Slips onto fuel sending units pickup tube / Available from Ford/autoparts stores.

All 1964/79 FoMoCo vehicles except Maverick/Comet/Pinto/Bobcat (use D1FZ-9A011-A 5/16" I.D.).

 

where did you hear the solenoid sound coming from, dash or underneath?

 

From underneath the cab.

I can turn the key with one hand while reaching under the cab with the other hand and feel the solenoid working. It's a very distinct clunking sound.