I have a problem with my rear Fuel tank not pumping fuel on 87 F150.
Rear tank is fully filled up and when I switch to Rear on selector switch it just suck gas out of Front tank. Sounds kind of like Fuel pump in rear tank is not working. any other ideas? have a full tank of gas on rear tank and it would be hard to drop the tank to check anything right now.

 

It maybe your fuel selector valve. You can open the bottom and see if you find any loose black 1/4" o rings. Its mounted on the frame rail under driver seat, its black with six fuel lines to it. 1987 to 1989 have a lot of problems with this. I replaced mine on 87 f150 4.9 EFI For more info. do a Advance Search above for selector valve see if someone has the same problem. Mine was always pumping fuel from the rear to the front tank, but i could not use my front tank. Some trucks do the opposite pump to the rear. Do you hear the rear in tank pump come on, you may have to have someone turn the key to on not run while you get next to the tank and listen. Check voltage at tank. Are the fuel lines kinked?

 

Thanks for a reply, Can I switch fuel lines around to see if selector valve is not working? I heard of recall on the valve but my vin# has no open recall when I checked on Ford website, but sometimes parts guy at dealer tells me the parts I was purchasing was recalled long time ago. I have to pay for them every time. do they close recalls after a few years? I doubt my truck had all the recall work mentioned in alldata done.

 

My truck done the same thing. I think it is your rear fuel pump. You can switch tanks but it does not matter it will still pull gas out of the front tank. The high pressure pump is still able to suck gas out of the front tank. The fuel pump has to be working properly so the selector can switch over. The selector works off of pressure from the pump in the tank. Your rear pump is probably not working. The selector is not switching to the rear tank causing the high pressure pump to work harder pulling gas out of the front tank.

 

thanks for inputs guys, I guess it's either one of fuel selecter valve or rear pump. I hear both of those parts are known to go bad, any improved part # for those components? it will be hard to get to rear pump, any easier way of getting the fuel pump removed for testing?

 

I do not know of any way to get to the pump besides dropping the fuel tank. You can usually hear the pump priming up when you turn the switch on. If you are wondering what it sounds like switch to the front tank and listen close, it should make the same noise when you switch to the rear tank. If you do not hear the pur then the fuel pump is either bad or the wiring is bad going to the pump. The pump is available at autozone but the selector valve is a dealer part only. The pump usually comes with a sending unit also and costs about $80 if I remember correctly

 

I believe there are two fuel pumps for the rear tank, one in the tank and the other mounted on the rail (for 5.0/302). There was also a Ford recall on the selector valve for certain years. The recall was based on the same symtoms your are describing. Go to the below link and enter your Vehicle ID Number to see if yours was affected by this recall:
http://www.ford.com/en/vehicles/owners/recalls/default.htm#ford

Also, the rear tank fuel pump will run you in the area of $109-$115 depending on where you go.

 

Recall was for 1989 fuel selector valve, it over now( 12 years). Ford said only one company that was making this part for them had problems. You have three pumps one high pressure pump frame mounted by the selector valve and one low pressure pump in each tank. Makes sense what Twm1974 is saying. TWM1974 if you switch the fuel selector valve to the rear tank how can it suck from the front tank? Did this happen on your truck? I heard its best to change both in tank fuel pumps if one is bad. Switching the fuel lines on my truck did not help when i had a bad fuel selector valve.

 

Yes it did happen to my truck. It kind of confused me when it happened. I do not think he has a valve problem. Like I said earlier in my other post the valve cannot switch without pressure from the pump. If the pump is not working then the valve stays in the same position which in his case it stays selected on the front tank. When you Change the position of the switch you switch the voltage to the pumps. What happens is the pump is not working on the front tank because you have switched it to the rear. The high pressure is always pumping and it keeps sucking out of the front. The rear tank pump is not working so your valve doesn't switch. The high pressure pump is for both tanks. The truck is fuel injected so it has to have a high pressure pump.My truck did exactly the same thing and to be honest, I was not so sure changing the pump would work. I checked and made sure the pump had voltage. It did and I listened for the pump which I did not hear. There was no doubt that the pump wasn't running because I could not hear it. I changed the pump and it fixed it. I only changed the one that was bad. If one of them still works why change it? I hope I have explained it okay. It does sound confusing to read it. It was confusing for me to type it.

 

I think I'm experiencing the same problem as twm1974, here is a little more info. when I switch to rear tank fuel guage reads full but fuel is just getting sucked out of front tank and I just run out of gas. when I switch to front tank gauge would read current fuel level in front tank and doesn't have a problem. Sounds like only thing wrong is rear pump not working.
I touched front tank and had someone turn on the key and quiet but felt something, switched to rear and did same thing to rear tank and didn't feel anything. It would be fun to lower that gas tank with a full tank of fuel, can I somehow transfer the fuel from rear tank to front? just a thought.

 

Check the voltage to the rear tank first, reach up and unplug the connector. You may have a break in the wire, it happens. You can remove the truck bed since the rear tank is full.

 

thanks for an advice, I will check the wire first. I think I'd pump gas out of the tank before taking the bed off as I don't have any mussle around the house. you all have been a big help!

 

I heard some people remove the filler kneck (Rubber hose) from the tank and then used a plastic hand pump and pump it into a plastic fuel container. Make sure you use a brass tool or wood block to remove the locking ring. I think you need a special tool to remove the two fuel lines retaining clips. Pressure wash under truck first. Use blocking under tank. Do a Advance Search above for more hints " removing fuel tank ". Good luck

 

that sounds like an idea there, getting a bit cold to work on cars outside here in Indianapolis.

 

I have one bit of advice for you guys to remember also. I wouldn't recommend running on the tank that doesn't work for too long. I didn't know that the fuel pump wouldn't cause the valve to switch over, but one day I flipped the switch to the back tank (which doesn't work) and it I guess the extra strain on the fuel pump caused it to die.

I do have a question for you fuel line experts out there. Does anyone know how the fuel return works with the 2 tank setup? I NEVER put gas in the back tank since the pump doesn't work, but when I switch over to it it reads a full tank. I haven't analyzed the return line, but I do know that there is only 1 line from the engine back.