Fuel Xfer Valve Wiring?

[DMAX_Phil]

I got a good deal on a F**d fuel transfer valve. It came off a 1996 F350. I'm hooking it up to my tank in the bed. The wiring on this thing has me baffled.

It has five wires. I hooked up the red and brn/wht and it switches as it should. I then keep the red powered and try all the other wires - nothing. I then start going through all the combinations and nothing. Two of the other three wires are shorted together inside the switch. So, I start switching polarity and going back through all combinations of the wires (including pairing wires up). It turns out that if I switch polarity on the red and brn/wht (the ones that originally switched) it switches back. I can get it to switch (front to rear and back) everytime but I have to switch the polarity each time on these two wires. This doesn't sound right and I don't know of any switch that would let me swith the legs from ground to hot and back on each leg. Maybe a double throw/double pole would but I'm not sure.

Anyone familiar with this valve or a wiring/switching scenario like I've described?


Phil B.

[DmaxMaverick]

Hey, Phil

Be very careful juicing all the wires. If you did hook up straight 12V to all of them, any circuit to ground would fry something inside the valve. I believe the valve is not ground operated, just ground insulated.

The wiring should go something like this, although I don't remember what the colors are. Two of the wires (likely the red/brn-wht you found) operate the valve, probably with the double throw/double pole method, not all are the same, and I'm not sure which you have.

The other 3 wires are the tank sender wires. 1 FROM each tank, and one TO the instrument panel. If you are not using a sender in the aux. tank, just blank off the sender wires.

You'll have to get your hands on a wiring diagram for the vehicle it came from to identify the correct hook-ups.

Good luck. Hope I didn't baffle you further.

[DMAX_Phil]

Thanks. I'll have to draw the schematic out for this since I'm having a hard time seeing how I can interchange the ground from one leg to another and then back. The switches I'm familiar with, switch the hot wire and not the ground. I'm starting to wonder if the valve is expecting some resistance on one of the lines or has an analog step function (e.g., 9V for front tank, 12V to switch to rear).


Phil B.

[ 05-18-2003: Message edited by: DMAX_Phil ]</p>

[DMAX_Phil]

Okay, I think I've got it. I had to look at the schematic for a double throw/double pole switch:

These are the six legs of a dt/dp switch

O - Brn/Wht = +
O - Red = -

O - Pos. Supply
O - Ground

O - Brn/Wht = -
O - Red = +

What I need to verify is that the ground is in-fact opened up on each leg when switched. I'll try a dp/dt switch with a momentary "on." I'll post some pics of this valve on my pic. site later. I'm running this valve in series with the aux. tank pump to avoid a siphon after the aux. pump is shut down.


Phil B.