Where do I find the fuel tank selector valve on an 87' F150, 5L, V8, 2WD?

The problem I'm having is that I switch to the rear tank, the fuel gauge indicates correct level but the front tank level is the one that is going down!

 

Bad fuel pump in or selector switch to rear fuel tank.

 

The Duel Function Reservoir is located on the drivers side frame rail before the high pressure fuel pump and fuel filter.

If the tank readings are showing correctly on both tanks when you flip the switch, then the switch should be working correctly.

I had the same problem with my 87 F-150 and the in-tank fuel pump was the problem not the reservoir or switch.

Install a new fuel pump/sending unit in the rear tank.

 

The switch works fine, hoping the fuel pump is OK, thats why I'm looking for where the valve is located.

Do you know where it is located?

 

I've changed the Duel Function Reservoir, high pressure fuel pump and fuel filter in the past.

Your saying there's NO selector valve?

 

Location as said above is on the drivers side frame rail under the bed:

Fuel tank selector valve:



Fuel layout:


Not true, just because the gauge part of the switch is working does not mean the pump side is making contact with both contacts.

The pump side is more likely to go bad then the gauge side as in the photo below:


Make sure you have power to the pump before changing it out by grounding pin #6 of the EEC self-test plug and turning on the key:


The wiring:
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I took out the troublesome Ford dual function reservoir (non electric tank switch valve) and replaced it with an electric switching valve. See writeup link in my signature.

 

Right, there is no selector valve only the DFR. You have a selector switch in the cab which switches power to the fuel pump in the selected tank (either front or rear). The DFR is switched by the pressure created by the in-tank pump that is energized.

SubFord makes a good point about the contacts in the switch not making a connection. I have not run into this personally, but it makes sense.

The fastest way to make sure your in-tank pump is working or not is to ground the #6 pin on the EEC self-test plug like subford post above. When you ground this pin, which ever tank (front or rear) is selected inside the cab is which pump should come on.

 

Kinda confusing but the DFR -IS- a selector valve. As you said it works in conjunction with the in-tank pumps. Here is a photo of the inside of my old DFR ('86)
http://img39.imageshack.us/img39/9895/valveinside.jpg
Showing the 2 valves and diaphragm.

 

I see your point/view on the valves. Dealing with these trucks, when someone is talking about a fuel selector valve, I think of the newer electric fuel switching valves and not the older DFR's that are in this model truck.

I do agree that the DFR is the switching valve for the duel tanks, but that is not its proper name and I just do not want to confuse anyone with the wrong wording of part names.

 

Great guys, thanks, I do have the mechanical selector switch/DFR.
SUBFORD, this EEC self-test plug is it homemade or can you elaborate more on the self-test please, Cause there is continuity between contacts 2-4 & 2-6?

 

Pin #2 is the same as ground but the ground circuit passes through the Computer.
So if pin #6 is shorted to ground the fuel pumps should run if the key is on.
If you connect pin #4 through a test light to the POS side of the battery it will flash out the codes if the STI wire is grounded and the key is turned on.
If you short pin #4 to pin #2 with the key on you can and will burn up the circuit inside the computer and it will no longer give out codes.

No there is nothing homemade, the self-test plug was made to plug into the STAR tester but there are a lot of after market testers out there to give you the codes.

A diagram with the ground paths shown (pin #2) (J1-46):


A diagram with the MIL (pin #4) shown (J1-17):


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See the link in my signature below for info on how to run the self tests and retrieve codes. I also have a writeup on the dual tank switching system.

 

Thanks klricks but, unable to open this link I keep receiving a 'Internet Explorer cannot display the webpage', I'd like to view it.

 

What version of IE? My IE version 8 works but I mostly use Firefox so maybe try a different browser.