Dual Tanks?
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Dual Tanks?
Am new member this is my first post appreciate any help. have had other Ford trucks with duals tanks but never any problems now have a problem switching tanks. Can anyone tell me how the switch under the dash works when switching from one tank to the other? Also there is a black cannister with 4 lines comming out of if just behind the pump and filter what is its function. Truck is 1989 F150 300 6 auto. Thanks
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Lead Driver
Joined: Nov 2002
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From: Concord, NC
The dash switch selects which in-tank fuel pump gets power. The black canister with the 6 lines going in and out of it is the selector valve, which is operated on pressure from the in-tank pumps. If one of the tank pumps fails, it won't switch tanks. Have a listen to see if each of the in-tank pumps are working.
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From: Easton,Ks
Originally Posted by dirtyneck
Am new member this is my first post appreciate any help. have had other Ford trucks with duals tanks but never any problems now have a problem switching tanks. Can anyone tell me how the switch under the dash works when switching from one tank to the other? Also there is a black cannister with 4 lines comming out of if just behind the pump and filter what is its function. Truck is 1989 F150 300 6 auto. Thanks
Note that the Fuel Pump Relay is grounded inside the EEC Computer.
Last edited by subford; Dec 4, 2005 at 08:17 AM.
Fleet Owner
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From: Easton,Ks
Originally Posted by dirtyneck
Am getting no power to either tank. Can someone tell me where 20 amp/guage fusible link is located? Thanks.
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Thanks for the help subford will check it out. meanwhile have hotwired dual tank switch to get power to rear tank with key on and am back on the road. Not correct but functional until I track down real problem, thanks again, Jim
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From: Concord, NC
Can you hear if the frame mounted high pressure pump is working? I don't think the truck would run off of just the in-tank pumps though, so maybe it is working. If the high pressure pump isn't working, then check the inertia cut-off switch. It could also be the fuel pump relay. Listen for that to click when the key is turned to "run" and then click off after a couple seconds.
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Thanks EPNCSU yes the frame mounted pump works and the rear in tank pump works when hot wired thru the dual tank under dask swith. I think I got a bad front in tank pump and a bad relay. Can you tell me where pump relay is located? Thanks, Jim
Post Fiend
Joined: Mar 2002
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From: Bonita Springs FL
The intank pump on a 1989 is not really needed. If it fails, the truck will still run. It's basically there to prime the high pressure pump if you run the tank dry. But I guess it could "help" the other pump out if it's weak/dying. Have you checked fuel pressure at the rail?
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From: Concord, NC
The in-tank pumps are needed to operate the tank switching valve, and to supply the high pressure pump with fuel. The electric fuel pumps push fuel fine, but are not as good at sucking fuel. That's why there is a lift pump in each tank to get fuel to the high pressure pump.
