Dual tank problem
Senior User
Joined: Aug 2004
Posts: 134
Likes: 0
From: Tennessee
sorry
When I bought the truck, I filled both tanks to the brim. I wanted to check fuel mileage. I ran the rear tank out till truck quit, then switched to front tank. It would not start even though the gauge moved to full.
So I put a gallon in the rear and switched back to the rear and it ran. I got it home and pulled it up on ramps and removed the hoses from the tanks to the mid pump and both tank pumps ran fine pumping gas very strong from both.
I have since still used the rear tank because it works and still have a full tank in the front. I would like to remove the front tank and just use the rear, I dont travel far when I drive it and can live with the rear tank and have access to a Bronco tank if needed for more capacity.
I drive a truck for a living and just have not had the time to do anything but start it or go get pizza a few times a month in it.
I want to shorten the exhaust so it sounds better then the full length duels it has now, I need to remove that front tank to have that done at the local exhaust shop.
So I put a gallon in the rear and switched back to the rear and it ran. I got it home and pulled it up on ramps and removed the hoses from the tanks to the mid pump and both tank pumps ran fine pumping gas very strong from both.
I have since still used the rear tank because it works and still have a full tank in the front. I would like to remove the front tank and just use the rear, I dont travel far when I drive it and can live with the rear tank and have access to a Bronco tank if needed for more capacity.
I drive a truck for a living and just have not had the time to do anything but start it or go get pizza a few times a month in it.
I want to shorten the exhaust so it sounds better then the full length duels it has now, I need to remove that front tank to have that done at the local exhaust shop.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
The front tanks fuel pump dose not have high enough pressure to switch the selector valve or the selector valve is bad.
But if you are going to remove them anyway that problem will go away.
So what do you want to know?
But if you are going to remove them anyway that problem will go away.
So what do you want to know?
New User
Joined: Oct 2005
Posts: 5
Likes: 0
From: El Paso, TX
New Issue, need help/advice
Thanks for the information thus far. Here is my issue. I have a 1996 F250, 460 engine, FI, and have the problem of the rear tank cross flow feeding the front tank. The rear tank seems to work fine, and the front pump works fine. However, the front guage goes to full whenever I put any amount of fuel into the front tank and stays there until I get to about 1/8 tank and then reads the remaining amount. I bought a 1992 model F150 for parts and removed the fuel pump and float assembly from the front tank in hopes that I could use it to fix my issue. Any advice as to whether this will work is appreciated.
Mountain Pass
Joined: Feb 2003
Posts: 158
Likes: 7
From: UP of Michigan
'88 F150, 4.9L, dual tanks
What should I check first if I hear no noise from either of my in-tank pumps? The truck runs until it warms up, then stalls.
Prior to this happening for the last few days, only the front tank would work, but the rear would work fine ONLY if it was below 20*. I'm trying to find the problem w/out throwing parts at it. I appreciate any help on where to start.
Prior to this happening for the last few days, only the front tank would work, but the rear would work fine ONLY if it was below 20*. I'm trying to find the problem w/out throwing parts at it. I appreciate any help on where to start.
New User
Joined: Dec 2005
Posts: 14
Likes: 0
boatbum
[I checked the fuel pres. at the rail and found no pressure so I took off the fuel line behind the(i could here the Hi speed pump run) hi speed pump and found no lo pressure from the 2 lo pres. pumps. (watch out for charged line it will squrt u)
I checked the wire at the dash rocker switch it has 6 wires 2 are power for the lo pres pumps and two are for gas gages, u should check the in coming power wire it was in the center on my switch and when u move it it shifts power from one tank to the others pumps. I found no power at that wire.when i jumped it from a power on when running wire the power returned to the lo pres pumps and it was fixed hope this helps.
I checked the wire at the dash rocker switch it has 6 wires 2 are power for the lo pres pumps and two are for gas gages, u should check the in coming power wire it was in the center on my switch and when u move it it shifts power from one tank to the others pumps. I found no power at that wire.when i jumped it from a power on when running wire the power returned to the lo pres pumps and it was fixed hope this helps.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Mountain Pass
Joined: Feb 2003
Posts: 158
Likes: 7
From: UP of Michigan
Ok, thanks. I'll test the wiring again tomorrow. That schrader valve couldn't be in a much worse location, of course. grrr.
Originally Posted by boatbum
[I checked the fuel pres. at the rail and found no pressure so I took off the fuel line behind the(i could here the Hi speed pump run) hi speed pump and found no lo pressure from the 2 lo pres. pumps. (watch out for charged line it will squrt u)
I checked the wire at the dash rocker switch it has 6 wires 2 are power for the lo pres pumps and two are for gas gages, u should check the in coming power wire it was in the center on my switch and when u move it it shifts power from one tank to the others pumps. I found no power at that wire.when i jumped it from a power on when running wire the power returned to the lo pres pumps and it was fixed hope this helps.
I checked the wire at the dash rocker switch it has 6 wires 2 are power for the lo pres pumps and two are for gas gages, u should check the in coming power wire it was in the center on my switch and when u move it it shifts power from one tank to the others pumps. I found no power at that wire.when i jumped it from a power on when running wire the power returned to the lo pres pumps and it was fixed hope this helps.
New User
Joined: Jan 2006
Posts: 2
Likes: 0
the selector switch is suppose to switch between sending units and fuel pumps. i'm pretty sure that year has a pump in each tank like my 90. so if the switch were actually working right then there's really no way for the front pump to be on when the rear pump should be on. sounds like the switch is either broken or mis-wired.
Mountain Pass
Joined: Feb 2003
Posts: 158
Likes: 7
From: UP of Michigan
I'm sorry for misunderstanding, but who is this addressed to? Which year?
Originally Posted by zenophryk
the selector switch is suppose to switch between sending units and fuel pumps. i'm pretty sure that year has a pump in each tank like my 90. so if the switch were actually working right then there's really no way for the front pump to be on when the rear pump should be on. sounds like the switch is either broken or mis-wired.
Mountain Pass
Joined: Feb 2003
Posts: 158
Likes: 7
From: UP of Michigan
2 bad pumps
Both of my in-tank pumps were bad. They have power going to them, so after fiddling with the connection, I tried a new one in the rear and it started humming. Apparently, the external pump supplys enough fuel if it's cold enough outside (~ under 30 degrees).
