where do the 6 wires go on the auxilarry fuel tank switch?

[powerwagonmaniac1]

Hey guys,

The guy I purchased the truck from has installed an electric switch for main and auxiliary tank. There is a plug on the back side of the switch that has 6 wires running from it. 2 of the wires are green and I think they run to the fuel gauge and 1 is orange this must be power (+). I also have 3 black ones these have been cut, where do they go? Are they a ground? Also the original tank valve on the floor has been replaced buy an electric pump which ahs been disconnected should the pump be wired into the swich for it to work or is it on on it's own circuit?.

Did ford put an electric fuel pump on the auxiliary tank and main tank or where they one pump for both tanks. Mine seems to be separate. The main tank works but I have no auxiliary tank at the moment. It has been disconnected due to a direct short someplace in the wiring. Does anyone have a wiring diagram for a 1970 F-250 showing this tank electrical switch? The mechanical switch on the floor does not work it uses an electrical valve to switch between the two.

I need to get the axillary tank back on line so I can use it on a long trip up to Cle Elum Wa. this summer.

Thanks for the advice,

Chris becker

[img]http://img.photobucket.com/albums/v238/ ... uck001.jpg

[68F250]

Hi! From what you describe, it sounds like you have the original fuel tank switch. The three black wires are cut like that from the factory, they are not used. The orange wire is the output that goes to the fuel gauge and the two green wires are the inputs from the main and aux tank senders. The switch configuration is a double pole double throw but only one side is used. The side not used has the black wires going to it. The only purpose this switch has is to switch between the main and aux tank senders.

No electric fuel pumps were installed at the factory. You'll have to trace out the wiring and see how the PO hooked them up. Shouldn't have anything to do with the tank switch unless they were clever.

[dcbullet]

Damn. I'm not trying to be a kiss ass but the knowledge here is incredible.

[jor]

Here's the schematic.
jor

[bluef250]

Does anyone know if the extra 3 wires were used in later models (1973 till ?) or in other models (Bronco) for the electric tank switch?

[FORDification]

'73-up trucks used a different switch, built into the heater control panel:

[powerwagonmaniac1]

Well guys,

I talked to the previous owner and he was telling me he was not sure what was burning up in the wiring. I can't find anything that got smoked.
The previous owner seems to have not been a very good mechanic as both Clayton ( the young man I purchased the truck from) and myself have been reparing the repairs he made! Go figure!!

The original switch on the floor is changed from the stock mechanical to an electrical switch that switches between the two tanks. This electrical switch has been disconnected. All the lines that would normally go to the mechanical switch on the floor are now plumbed into this non working electrical switch. It is open to the main tank, so it runs. Now we are going to try hitching it back up and see what happens. I'll have to install a toggle switch on dash board to work the fuel tanks. Would there be any way to tie it into the original fuel tank switch for the gauges?

There looks to be a small red light mounted to the far left of the ignition switch on the dash board thats been painted over. It looks factory. Would this be an indicator light for the auxiliary tanks to let the driver know it is being used?

I checked my wiring under there and it is still hitched up like it came from the factory the two green wires going to the input on the sender units and the orange going to the gauge. So everything looks fine under the dash what else would I need to do to make the switch work to use both tanks? By the way are there fuel filters on the tanks that need replacing? Thanks for the schematic it will help tomorrow when I can look at it again.

Thanks,

Chris Becker

[FORDification]

If you're talking about the little light down by the e-brake, that's a brake warning light. It's hooked up to your brake distribution block to warn you of brake problems, like losing pressure in either the front or rear brake circuits.

[68F250]

Would there be any way to tie it into the original fuel tank switch for the gauges?

I'm not sure how your electric fuel valve and fuel pumps are all wired together but there is a way to utilize the nonused part of the selector switch to send power out to the main or auxiliary tank. I tried to edit the wiring diagram where the switch is shown. Arrows point to the unused contacts where the black wires go to. If you feed +12 volts to the center contact (Tank Power In), the switch can direct it to one side or the other unused contact. The new switchable main and aux. power outputs can go to the electric fuel valve and appropriate fuel pumps. The power you feed the center contact should only be live when the key is in the "on" or "start" positions.