Ok, I know there are many posts on duel tank issues but Im stuck. 1985 f250, 7.5L. Ive owned this truck for 15+ years so theres not much I have not dealt with. Recently when running low, ok out of gas on the rear tank I switched to the front tankt that is full, and the truck continued to die. Gage did not respond when I flipped to the front. I put gas in the rear (switch set to rear now) and got on my way. Thinking it was the fuel pump relay (had same exact issue in 2000 and it was the relay) I changed the relay and nothing changed.

When I switch from rear to front, the gage drops down showing empty, even though the tank is full. I checked fuses, there is a 10amp fuse in slot 6 (i think) that my manual says operates 'relays', does not say which one. When I switch from front to rear and visa versa, I hear the selector under the truck click, so it sounds like it is working and also makes me think the switch is working.

Does anyone have an idea why it seems the truck selector is clicking like its doing its job, but I have no gas pumping from the front tank AND the fuel gage is not registering full for the front tank.

I thought maybe the pump was bad, but if that was the case why would the gage not be responding also?

Not the relay since this is new. Does not seem to be the switch since I hear the selector click (hard to hear the pump, I will need to check this when I can be under the truck why someone else switches back and forth). and since I hear the selector switch I dont think its that.

Any suggestions? Stuck with $40 in gas in the front tank sucks. Also, tried using a pump to siphon out the gas, but it seems that the hose was not getting in the tank, is there a screen or something preventing me from putting a hose in the tank?

Thanks.

 

Just because you hear the selector clicking doesn't necessarily mean its working. Quick check would be to disconnect the fuel line to the carb from the selector and see.

 

Dean, I would say that the selector valve is getting stuck. I would switch it to the front and try to siphon gas through the valve. Also, I believe that when you switch tanks it also changes the active wires going to your fuel level sending unit. That is why it shows empty. I think if you replace the valve you should be up and working again.

 

Interesting, I'm having the exact same problem with my '81, I6.

Selector switch rear: Feeds off rear tank, gauge works.
Selector switch front: Feeds off rear tank, gauge reads empty.

For the benefit of everyone:

Where is the valve located? And is it different for different engines/fuels/years?

 

The valve is located on the frame rail just ahead of the front tank. It should be secured with 2 bolts. Just follow the fuel lines from the tanks and it will to into a 2-to-1 valve. It looks like this:

 

There are the 3-hose and 6-hose variants, I forget the specifics but it's in the archives somewhere. If he's in the right mood, NumberDummy will foam at the mouth about a certain year range of those things......

 

here are the Aftermarket part numbers from Rock Auto:

3-port - AIRTEX / WELLS Part # 8F1311

6-port - AIRTEX / WELLS Part # 8F1312

I would think that the 6 port is for the fuel return lines on those that have them.

 

I think replacing the selector valve may be my next step, just a bummer for a truck I rarely drive anymore. From what I have seen I think Ive been lucky Ive never had to replace this. Owned the truck since the mid 90's, only the second owner and I think this has never been changed.

Thanks, If anyone has any suggestions for rebuilding or quick fixes other than putting on a new part please let me know.

 

Stuff happens and things go bad. As you said you're lucky... Rock auto has both styles. I think you should have the 3 port valve and it's $80. Just feel lucky that you're fuel gauge works. Mine do not but the selector valve does. :S

 

Thanks, I have the 6 port on this model, I can pick up the part locally. Appreciate the input.