I am having problems with my 1990 f-150 pumping the fuel back and forth between the 2 tanks.
The people at autozone were very helpful and said it is my fuel selector valve, and showed it to me. I didn't go ahead and buy it cause I wanted to get the old one off and match it up.

Now the problem.... I can't find it on the truck.
I have traced the fuel lines from rear tank to intermediate tank to filter to engine and haven't found it. The only possibilities I can think of are that either I don't have one or it is on top of the rear tank and I have to drop the tank.
Can anyone help?

 

[font size="1" color="#FF0000"]LAST EDITED ON 26-Aug-00 AT 11:44 PM (EST)[/font][p]The valve should be located on the drivers side frame rail below the rear of the cab behind the fuel filter. There should be 6 fuel/ return lines into/ out of it. Held on by 2 bolts thru the frame. Probably has a 6 /- wire connector harness; its black plastic; and as I recall, is not cheap. The fuel lines use quick-connects that aren't always easy to quickly disconnect without breaking something...

 

Greetings,

I'm a newbie here, and I may have my data mixed, but for what it's worth...

I was just reading in the Recall/TSBs section on this site about a recall on the models with 2 tanks...something about the check valve leaking back and possibly over-pressurizing a full tank.

I "drilled-down" thru menus checking for my (newly acquired) '91 F150, and found this:


NHTSA CAMPAIGN ID Number: 93V125000

Summary:

A MALFUNCTIONING CHECK VALVE WITHIN THE FUEL PUMP ASSEMBLY CAUSES A PORTION OF THE
UNUSED FUEL FROM ONE TANK TO BE RETURNED TO THE SECOND TANK. WHEN THIS OCCURS, THE
CAPACITY OF THE SECOND TANK CAN BE EXCEEDED, CAUSING FUEL SPILLAGE.

SPILLED FUEL CAN RESULT IN A FIRE WHEN EXPOSED TO ASOURCE OF IGNITION.


Good luck, Denny

 

Bob,
Does your fuel selector valve switch between tanks correctly...that is, does the fuel gauge show what's in each tank when you select tanks with the switch? If so, it's probably not your selector valve. If your truck is pumping fuel (cross filling) between tanks, you have a bad check valve on one of your fuel pumps. The check valves are built into the fuel pumps. The tank that overfills, accepts gas from the other tank, generally has a bad fuel pump check valve. Mine did this recently. When I selected the back tank, the gas would go into the front tank and sometimes overfill/overflow that tank. Solution? Change the fuel pump in the tank that overfills (accepts fuel from the other tank...in my case the front tank) because its check valve is bad and is letting gas into its tank. Fuel pumps cost almost $200 each, so shop around for best price. But, they are not hard to change. The easiest way to get at them is to lift the bed off or scoot it back so you can get to the tanks/pumps. Dropping the tank is a major pain in the butt.
I went to a local shop and had them loosen the six nuts on the six bed retaining bolts. Then I went home, pulled the nuts off myself, undid the tailight wires at the connector, took the tailgate off and spare tire off its bed-mounted carrier, and removed both license plate lights and then duct taped the lights up to the bottom of the bed. Then I pulled the bed bolts out of their holes, loosened the clamps on the tank filler hoses and lifted and pulled the bed straight back and up/over the rear tires until I could get to the front tank and pump. If you've got a buddy handy, you can each grab the bed at the wheel wells and just lift it off and back. The bed doesn't weight that much, really. Now you can get to the fuel pumps with ease! Just remember that the tank that overfills, or accepts gas from the other tank is the one with the bad fuel pump & check valve. It only takes about an hour to replace the pump after you get the bed out of the way. If both your tanks are cross filling, you may have to do both pumps. I wouldn't suspect your selector valve unless it's obvious that it isn't switching tanks.

 

bob:

If gas is going into both tanks, sounds like you will need both fuel pumps. There are actually 2 check valves in each fuel pump; one for the supply side and one for the return side, called a shuttle valve. See if you can return the fuel selector valve to those nice guys at Autozone and get the recall (Ford recall number is 93S68), work done at a Ford dealer. If they say that your truck was not in the recall or the recall has already been done to it, report it to the National Highway Traffic Safety Administration at: www.nhtsa.dot.gov

The NHTSA has an investigation on this problem, because the recall fix isn't working well,and there is only a 12 month/12,000 mile warranty on the recall fix.

We've seen a lot of these at our shop, and they can be pretty expensive to fix, especially if both pumps need to be replaced. I don't understand why Ford's 12/12 recall warranty doesn't enrage more people. For example, if Ford had a recall on wheel studs, and yours broke and a wheel fell off 13 months after they did the recall, you would have to pay for the repair. It's bizarre. Good luck with your truck.

 

Thanks for the info guys. In the mean time I had come accross the recall info and am persuing that route.

To the guy that explained where the selector valve etc should be, evidently that isn't true on mine. There is no valve at all on the lines between the tanks and the filter. just a couple of "Y"s The other line runs undisturbed to the engine. The valves must be part of the fuel pump like some of the others are saying.

Any way thanks for the info and help

Think I will give this 1990 a new home and start driving my 2000 GMC Sierra.

 

 

I have an 89 F-350 with the 7.5L I replaced the front tank and guts, in line pump, filter, pressure regulator and injectors. The rear tank was gone when I bought it. I bypassed the tank selector valve by running the sending line from the tank directly to the in-line pump and I ran the return line directly from the fuel rail to the tank. So, all rear lines are disconnected, and the tank selector switch is not in play, however the tank selector switch is still hooked up, but I haven't checked to see if it's getting power. The fuel gauge shows full no matter what position the tank selector switch is in and I know it is not full because I installed the tank new and only put in 5 gallons. I wanted to test if it would pick up fuel and also look for leaks, so I ran power directly to the in-line fuel pump. It pumps fuel to the rails, but the engine isn't starting. The in-line pump to me just seems like it is for priming the system and then the pump in the tank would do the rest...right? Also do I need to put in some kind of jumper to get the selector switch to read my fuel gauge correctly? What about the fuel sending unit relay? I haven't replaced it yet. I'm sure this is a wiring issue of some kind, but I'm lost as to what to do next. Any ideas?

 

You might want to start a new thread to get better response results. Did the truck run before you did all this work? I would check the voltage leaving the in dash fuel tank selector switch, going to the in tank fuel pump first. Then check for voltage at the connector on top of the fuel tank, going to the in tank pump. Since one tank was removed, the wiring at the selector switch may have been changed.

 

After verifying voltage to the in tank fuel pump, check your timing. Being set up for propane previously, your timing could be off. How are your vacuum lines to your fuel pressure regulator and MAP sensor?

 

Good point on the selector switch. I'll look at that next! Thanks!

 

Timing was redone for gas when we rebuilt the engine. It had a smog delete done before I bought it. I put a new fuel pressure regulator on it. The line coming from it the MAP sensor looks terrible. I should probably replace it and see if it helps. May just do a new MAP sensor too while I'm at it.

 

I would recommend just replacing the vacuum line to the MAP sensor and see if the no start situation improves. Replacing multiple components can make troubleshooting more difficult. The MAP sensor can be electrically tested if need be.

 

https://www.ford-trucks.com/forums/8...-question.html

 

On my 1990 f150 302 ..I had the box off and redid the whole fuel tank deal as my rear pump was shot.
there is no selector valve ..let’s say you switch to the front tank..the front pump works and pressurize the fuel lines.
the fuel pump module in the rear tank contains a o one way valve that stops fuel flowing into the rear tank.
so the fuel lines up to the engine and down the Y leading to the rear tank are all pressurized..but the fuel cannot enter th3 tank because of the
one way valve built in to the fuel modules in each tank.
all the switch does on the dash is switch power between 1 or the other fuel pump.
that’s how it works in my 1990 f 150 and I belive that why you could not find the selection valve ..cause there ain’t one