1996 F-250 Dual Tank Wierdness
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1996 F-250 Dual Tank Wierdness
I have a 1996 F-250 with a 7.5 / 460 fuel injected V8. It has Knapheide Boxes on the back, so it has duel fuel tanks.
It sat for 3+ years and was re-awoken this past spring, but when I tried to start it on the front tank, the fuel pump didn't make a hum, and the truck didn't start.
I've been running fine on the rear tank since May.
Today I went to town and after coming out of the store, I saw fuel dripping from the vent hole next to the cap on the front tank.
The tank supposedly only had maybe 3 gallons of gas in it (approx 15 gal tank).
I can only envision 3 scenarios.
1. Front tank has a leak somewhere that has allowed water inside. With the tool box covering it I don't see how this is possible.
2. Someone poured water into the tank. Not very likely.
3. Gas from the rear tank is somehow being pumped into the front tank - while the truck is running perfectly.
Thanks in advance for thoughts ideas etc...
It sat for 3+ years and was re-awoken this past spring, but when I tried to start it on the front tank, the fuel pump didn't make a hum, and the truck didn't start.
I've been running fine on the rear tank since May.
Today I went to town and after coming out of the store, I saw fuel dripping from the vent hole next to the cap on the front tank.
The tank supposedly only had maybe 3 gallons of gas in it (approx 15 gal tank).
I can only envision 3 scenarios.
1. Front tank has a leak somewhere that has allowed water inside. With the tool box covering it I don't see how this is possible.
2. Someone poured water into the tank. Not very likely.
3. Gas from the rear tank is somehow being pumped into the front tank - while the truck is running perfectly.
Thanks in advance for thoughts ideas etc...
Fleet Mechanic
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From: Candy Mountain
#3 is the winner! Common problem. Lots of threads on the subject. You have a failed check valve in the Fuel Delivery Module of the front tank.
https://www.ford-trucks.com/forums/1...p-front-2.html
https://www.ford-trucks.com/forums/1...p-front-2.html
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#3 is the winner! Common problem. Lots of threads on the subject. You have a failed check valve in the Fuel Delivery Module of the front tank.
https://www.ford-trucks.com/forums/1...p-front-2.html
https://www.ford-trucks.com/forums/1...p-front-2.html
Looking through that thread it appears that I have 3 options at this point.
1. Cut the lines to the front tank and plug them. I'm not willing to do this.
2. Replace that tank selector switch on the dash to see if that will remedy the issue. This MAY also remedy the issue of the front tank pump not working.
3. Replace the entire (front tank) fuel pump / sending unit assembly, as the FDM is part of it.
Thoughts?
Fleet Mechanic
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From: Candy Mountain
Check the switch function with a multi-meter. Subford or a few of the others can post up a wiring diagram if you need it. It is also possible a PO hacked or disconnected the wiring to the front tank. This may be hard to determine without dropping the tank. If the switch is not the problem, option 3 is again a winner. If none of it has been in service for years I would replace it all wholesale.
If you have to go down this road, some folks like to pull the bed for ease of access. It would be a good time to look at the fuel vapor hoses, and most likely replace them on both tanks. If they are in bad shape, it is fuel vapor you are leaking and not burning, which is the same as throwing money away.
If you have to go down this road, some folks like to pull the bed for ease of access. It would be a good time to look at the fuel vapor hoses, and most likely replace them on both tanks. If they are in bad shape, it is fuel vapor you are leaking and not burning, which is the same as throwing money away.
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Check the switch function with a multi-meter. Subford or a few of the others can post up a wiring diagram if you need it. It is also possible a PO hacked or disconnected the wiring to the front tank. This may be hard to determine without dropping the tank. If the switch is not the problem, option 3 is again a winner. If none of it has been in service for years I would replace it all wholesale.
If you have to go down this road, some folks like to pull the bed for ease of access. It would be a good time to look at the fuel vapor hoses, and most likely replace them on both tanks. If they are in bad shape, it is fuel vapor you are leaking and not burning, which is the same as throwing money away.
If you have to go down this road, some folks like to pull the bed for ease of access. It would be a good time to look at the fuel vapor hoses, and most likely replace them on both tanks. If they are in bad shape, it is fuel vapor you are leaking and not burning, which is the same as throwing money away.
Switch & wiring first it is then. Thank you again kind sir.
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There was actually a recall, ford sent us check valves to click right on fuel pumps. I was at the dealer then...
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Do you remember what year did you get the checkvalves?
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More wierdness.
I parked the truck Nov 1st the same day I posted - and didn't drive again until yesterday the 7th.
I removed the cap from the tank - and the gas level had gone "down" in the sense that I can't see gas in the neck.
What could cause it to drop so far?
I picked up the tank selector switch yesterday and will install it tomorrow when it warms up to 40* outside.
I parked the truck Nov 1st the same day I posted - and didn't drive again until yesterday the 7th.
I removed the cap from the tank - and the gas level had gone "down" in the sense that I can't see gas in the neck.
What could cause it to drop so far?
I picked up the tank selector switch yesterday and will install it tomorrow when it warms up to 40* outside.
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From: Northern VA
Fleet Mechanic
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From: Candy Mountain
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