My fuel tanks will not switch from front to rear. The truck is running off of the front tank, I had noticed that when I flipped the tanks over the last couple of times that the fuel gauge took a while to go to full, finally it quit switching all together. I verifed it by starting the truck when cool, then feeling of the lines at the transfer valve on the frame rail to determine which tank was feeding the engine. I checked the fuse, ok. Is it safe to say the transfer valve is bad? Any ideas on what to check, part numbers and prices for the transfer valve, and is this a Ford only part? Thnaks for any help, have not been to the site in a while, have not had any problems until now!
fuel tank transfer switch/valve
1 - 18 of 18 Posts
Joined
·
1,672 Posts
I think if you check it is the electric pump in the tank. that will explain why your guage dont do right.Ford went to a prepump in the tank and it starts the flow.
Inside the fuel selector valve is an electric motor, and the motor is run forward or reverse to do the switching. There are a pair of diodes and a set of contacts in there that remove power to the motor when it completes its motion. The valve will not function if:
The motor goes bad.
The contacts go bad.
A diode burns out.
The voltage polarity doesn't change (could be bad switch on console)
You can find out something about the problem by looking at pins 1 and 2 on the 5 pin connector on the valve. Put your ohm meter on pins 1 and 2 and set it for diode check. You should get continuity in one of the two directions. If you apply 12 volts to these pins, and then reverse the polarity the valve will switch. If it doesn't then the problem is internal. It appears on some of them you can take them apart, and it may be repairable but I've not tried.
The motor goes bad.
The contacts go bad.
A diode burns out.
The voltage polarity doesn't change (could be bad switch on console)
You can find out something about the problem by looking at pins 1 and 2 on the 5 pin connector on the valve. Put your ohm meter on pins 1 and 2 and set it for diode check. You should get continuity in one of the two directions. If you apply 12 volts to these pins, and then reverse the polarity the valve will switch. If it doesn't then the problem is internal. It appears on some of them you can take them apart, and it may be repairable but I've not tried.
Joined
·
1,672 Posts
[ QUOTE ]
Not in a diesel they didn't!...
[/ QUOTE ]
So what did they use?
Not in a diesel they didn't!...
[/ QUOTE ]
So what did they use?
Joined
·
1,672 Posts
[ QUOTE ]
There is a mechanical pump on the engine. That's it.
[/ QUOTE ]
So what switches the fuel from one tank to the other?
There is a mechanical pump on the engine. That's it.
[/ QUOTE ]
So what switches the fuel from one tank to the other?
Joined
·
1,672 Posts
If you are talking about the fuel tanks on your 89 ford truck there is a pre pump in the tank just like GM uses to start the flow of fuel and then it is picked up by the manual pump 0n the moter.When you turn the selector switch on the dash to mid it then starts the pre pump in the mid tank.
You may wanna try your dash switch first. It's easier than unbolting the tank to get to that tank switch unit. There's a way to test if that's it. I forget what wire you have to put to what. Ask someone ere. I changed my unit thinking it was the problem come to find out it was just the dash switch.
Check the switch and any fuses first. If the valve is bad, you can get a universal fit one for about $75 but you will need to change the hose ends and the wiring plug. Pollack makes the OEM Ford version -some good parts stores can get them direct, it is a bolt in and costs about 2x that instead of 3x at the ford dealer. Also get the plastic clips - Help! has the clips for 2 for $1.29 - the dealer banged me $5 each originally until I returned them. Next to ice; dirt and rust jamming the valve are the leading reasons for failure. Let me dig around, I may have an extra one (used) for a 1993 (will see if they are compatible).
FYI, there was a recall on some ford trucks late 80s model years, check to see if you are covered - Ford recall # 91S39
Dan
FYI, there was a recall on some ford trucks late 80s model years, check to see if you are covered - Ford recall # 91S39
Dan
Joined
·
12,232 Posts
[ QUOTE ]
What switches the tanks is a selector valve. There is no electrical fuel pump in any diesel fuel tank. Not from the factory anyway.
[/ QUOTE ]
Not on the IDI engines, later models do have tank fuel pumps........
If you want the later model 89-94 FSV tests send me a pm with your email addy.........mention FSV test.
What switches the tanks is a selector valve. There is no electrical fuel pump in any diesel fuel tank. Not from the factory anyway.
[/ QUOTE ]
Not on the IDI engines, later models do have tank fuel pumps........
If you want the later model 89-94 FSV tests send me a pm with your email addy.........mention FSV test.
My last trip this happened about 40 miles from home. The fuel gauge didn't register and there was gradual loss of power. I flipped it back but it seemed to continue to lose power. After a few flips back and forth the gauge registered, power returned, as did my smile.
A little pat to the dorf that takes me home...
I think I'll check that switch.
Bruce
A little pat to the dorf that takes me home...
I think I'll check that switch.
Bruce
I don't like the universal tank selectors either. a few $ saved won't be a bargain when it acts up 1,000 miles from home. Wish I had one of those yards around here. $20 minimum charge for anything. They get pissed when you tell them that their prices are higher than the dealer (which they are sometimes).
1 - 18 of 18 Posts
