My front tank registers empty all the time. I forgot who suggested that I fill both tanks and reset the trip meter. Then when I hit 190 miles or so on the front tank, switch to the rear and repeat process when empty. I did exactly that and thought it was a great idea to use both tanks to prevent problems.

Today in just checking, I noticed my fuel level is going down on my rear tank as I use the front tank. It appears the front tank is not being used. Now I don't know what is going on. I know these dual tanks can be a problem but I am confused now. What is going on please? Thanks Sandy

 

Ford had a problem with the relays/switches that controlled the tanks. Most notably the fuel would return to the opposite tank. It's entirely possible your switches are bad. Talk to a dealer and see if the TSB on your truck was ever done.

 

I have the print out of where the one owner PO had his entire service done. They replaced the Front fuel pump and replaced a (module?). The fuel regulator was replaced and a front fuel s ($199.00????) All of this was done 3,000 miles ago. The rear pump was replaced about 5K ago.

I assume my truck is pulling gas from the rear tank because that gauge is showing reduced gas when I switch to the rear. Switching to the front tank shows empty but it is full. Is the dash switch the only source used for switching tanks? If so it is likely my dash switch is bad perhaps? If not what switches are you referring to? Thank Sandy

 

It could also be possible that the front tank float either is or is going bad. My trucks front float works whenever it wants to. I just run the front tank down first.

 

I would think either that or the sending unit. As far as running the front tank, that is what I was trying to do but I am using gas from the rear tank. I don't think I explained it very good.

1. Fill both tanks
2. Rear tank shows full and front shows empty
3. Set Trip and put switch on front tank showing empty and go because I have fuel.
4. Few days later put switch on rear just to check and it is down 1/4. Switch back to front tank.
5 Few days later switch to rear tank to check and it is down to 1/2.
6. Come here for help

 

Any help will be greatly appreciated. Thanks Sandy

 

Is the front pump running when the front tank is selected or is the rear pump. Maybe it was rewired?

 

A switch rewire is pretty much the only way this could happen, there is no other mechanism to switch between tanks on this vintage truck.

 

Thanks guys. I hear the rear pump when the dash switch is on rear. I do not hear the front tank pump when I switch to front. I hope this sheds more light. What switch do you think is rewired and where is it and I will fix it if you still feel like that is my issue. Thanks so much as I really want to fix this. Sandy

 

There is only 1 switch.. the one on the dash.

 

OK Thanks. Sandy

 

I have pulled the tank selector switch which the forum said it seems someone may have rewired the switch incorrectly. I need help as I can not read a schematic.

Looking at the picture is as if sitting in truck with the connector in the dash ready for the switch, these are the wire colors as I found them. Are they correct or wrong?

Top Left Brown/white Top right Yellow/blue
Middle left Red/yellow Middle right Yellow/white
Bottom left Red Bottom right Blue/yellow

 

IF it is wired correctly could it be just the switch itself?

 

The wire colors and pin locations look correct according to my Ford service manual.

 

Yes it could be a bad switch.