can't find the tank selector valve. it switches by itself and when fuel line runs out i change tank on switch on dash.

 

What year?
There is no selector valve. The switch switches only the in-tank pump and sending unit. The rest is "magic", when it works.

Winford

 

Actually there is a switching unit. Since the truck in fuel injected with positive pressure and more fuel than will be burned (unlike a carburated engine) the unused fuel is returned to whichever tank is currently selected. If the switching unit between the tanks in not working properly you can feed out of one tank and have the return go to another. This will not be good when the return tank is filled to overflowing and fuel begins to be pumped overboard through the fill neck. All the recalls on this have expired. It is about $450 at Ford to repair the unit, if they can get the parts.

I think the fail position is to the front tank. So, if you have a bad unit and do not have the cash, feed from the front tank first until it is about 1/2 empty then switch to the rear. This will allow the return a place to go. It will look like you are burning gas faster but in fact it is back in front. Fuel management in a truck, imagine that! Reminds me of my old '68 V-tail Beech Bonanza.

 

Actually there are two different types. I have had both. I had a 92 F150 with dual tanks, all the "smarts" are in the tanks.

I now have an 88 F150 with the switching reservour external, between the tanks and the external pump. That unit costs $61.50 from Lou Fusz Ford - I just bought one which I am waiting to install until I empty the tanks a little.

There is no switching valve arrangement. I have had the tanks down, and traced the plumbing. The reservour and the external pump are all the "lumps" in the system. I actually took the old reservour off and cleaned it, hoping that would help, but it didn't. It is listed and non-serviceable. Although it is called a reservour, it has some springs and diaphrams and check valves which, when working properly, keep the return fuel in the correct tank. It has six connections. Also a problem is not only the return fuel, but when parked downhill with a full rear tank, it will siphon into the front tank, and even overflow.

The 92 (I don't know exactly what year they changed) didn't have this apparatus, and neither did it have an external pump. That is why the internal pump assembly costs more (I guess), because it has to control the return flow.

Bottom line, like I stated earlier, is that the only electrical connection/switching is the fuel pump power and sending unit - unless the newer type has in-take soleniod valves (I doubt). If so I would like to see a picture. None of my manuals mention them.



Winford