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1988 f-350 fuel problems

i just bought a 1988 f-350 equipped with the 460 and dual fuel tanks. when i unloaded the truck from the trailer, it would not start. i put about 3 gallons in the rear tank, and now it starts, but it still continues to run when i switch to the front tank. the switch in the dash is new. also, none of the gauges in the cluster worked. i replaced with a junk yard unit, and now the voltage gauge works but none of the others including fuel. i know the high pressure fuel pump is coming on because it is quite noisy, but not sure if the in tank fuel pumps are working. i have heard that the high pressure pump is capable of pumping fuel through an inoperable in tank pump. could i have a ground problem somewhere based on the temp, oil pressure, and fuel gauges not working? could this all be related? please help with some direction.
 

larrylass

New Jersey Chapter member
i just bought a 1988 f-350 equipped with the 460 and dual fuel tanks. when i unloaded the truck from the trailer, it would not start. i put about 3 gallons in the rear tank, and now it starts, but it still continues to run when i switch to the front tank. the switch in the dash is new. also, none of the gauges in the cluster worked. i replaced with a junk yard unit, and now the voltage gauge works but none of the others including fuel. i know the high pressure fuel pump is coming on because it is quite noisy, but not sure if the in tank fuel pumps are working. i have heard that the high pressure pump is capable of pumping fuel through an inoperable in tank pump. could i have a ground problem somewhere based on the temp, oil pressure, and fuel gauges not working? could this all be related? please help with some direction.

I would look at this. On these year trucks is a black canister looking object attached to the frame rail on the drivers side. It looks like a filter of some sort but its the infamous "manual fuel tank selector valve" it allows gas from one tank or another to flow to the inline fuel pump. ill look for the link that explains this POS thing the brilliant FORD engineers designed. Anyway the way it works is it has a set of diaphrams in side the canister that will open or close depending on which fuel pump is selected. your in tank fuel pumps only produce 8-10 psi of fuel pressure so as designed to work with this selector valve and the Fuel PSI is boosted buy your inline fuel pump. If you remove this selector valve be very careful as they break easily and whatever you do DONOT remove the bottom bowl!! If this selector valve is defective it will allow all the fuel to go from the front tank to the rear tank and out the fill tube. Ford is the only place you can get this selector vave and its pricey. I would be going to the pick and pull and find a 88-91 f150-f350 truck.

Hope this helps
Biglar
 

larrylass

New Jersey Chapter member
I would look at this. On these year trucks is a black canister looking object attached to the frame rail on the drivers side. It looks like a filter of some sort but its the infamous "manual fuel tank selector valve" it allows gas from one tank or another to flow to the inline fuel pump. ill look for the link that explains this POS thing the brilliant FORD engineers designed. Anyway the way it works is it has a set of diaphrams in side the canister that will open or close depending on which fuel pump is selected. your in tank fuel pumps only produce 8-10 psi of fuel pressure so as designed to work with this selector valve and the Fuel PSI is boosted buy your inline fuel pump. If you remove this selector valve be very careful as they break easily and whatever you do DONOT remove the bottom bowl!! If this selector valve is defective it will allow all the fuel to go from the front tank to the rear tank and out the fill tube. Ford is the only place you can get this selector vave and its pricey. I would be going to the pick and pull and find a 88-91 f150-f350 truck.

Hope this helps
Biglar

Manual fuel selector valve assembly part #:
Selector valve assy, p/n F1UZ-9B263-B
heres the part #
 
thanks for the tip. ill look into that on monday when i get some time. any ideas on where i should look to get my fuel gauge working? right now it shows way past full regardless of which tank i select. it never moves.
 

larrylass

New Jersey Chapter member
thanks for the tip. ill look into that on monday when i get some time. any ideas on where i should look to get my fuel gauge working? right now it shows way past full regardless of which tank i select. it never moves.

The fuel pump- sending unit is located inside the tank. You can check the wire connections but i believe they are on the top of the tank so thats going to be a bear to check. maybe someone else has a suggestion

BigLar
 

Fellro

Moderator
Staff member
It isn't entirely uncommon for the fuel senders to fail, which will give a full reading all the time. I have the same issue on my 88 250, it will waver some when it gets in the middle, then it will read empty a little while, then back to full. I haven't had time to fully check the hookups, but figure the sender itself is failed. My truck is the opposite of yours though, the rear won't run and the front will. I haven't checked if the pump finally died or not though. It is definitely also possible the tank valve has crapped out, not unusual either.
 

dustybumpers

don't play well w others
if you have more than 1/4 tank, it will be picked up by the pressure pump, and act like pump is working. if tank is not switching, may be that both lift pumps are not working. since the guages are not working as well, I suspect you have a ground issue, and fixing that may also fix your pump/guage issues
 

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