Very weird problem please help!
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Very weird problem please help!
Hi, I have a 86 F150 with the 302 EFI, Auto Trans, 2 fuel tanks.
Last weekend I had to change the filler neck on the rear tank because it was cracked. I pulled the tank, drained and cleaned it. When putting everything back I noticed the breather tube on the top of the tank was never hooked up so I hooked it up.
now the weird issue. The front gas tank (which has never worked since i bought it 2 months ago) builds pressure and gas comes out the filler neck after driving around for a little while. WTF? The only difference is a new filler neck on the rear tank and i hooked up the breather tube. That breather tube does connect with the breather tube on the front tank so i disconnected it again but it still builds pressure in the front tank until gas comes out the filler neck. I don't have a clue what could cause this. Please help!
Thanks,
Shane
Last weekend I had to change the filler neck on the rear tank because it was cracked. I pulled the tank, drained and cleaned it. When putting everything back I noticed the breather tube on the top of the tank was never hooked up so I hooked it up.
now the weird issue. The front gas tank (which has never worked since i bought it 2 months ago) builds pressure and gas comes out the filler neck after driving around for a little while. WTF? The only difference is a new filler neck on the rear tank and i hooked up the breather tube. That breather tube does connect with the breather tube on the front tank so i disconnected it again but it still builds pressure in the front tank until gas comes out the filler neck. I don't have a clue what could cause this. Please help!
Thanks,
Shane
FTE Legend
Joined: Jul 2010
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From: Northeast, OK
I agree. The tank selector valves on the later trucks also switched the return IIRC. And the valves can do strange things - like pump from one tank and return to the other. I've seen it. You can get a repair kit at the parts store for the line sizes you have and splice around the selector valve to prove that's the problem.
Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
NumberDummy is the expert on those things, could probably search this forum for all posts authored by him with keywords of "selector valve" and get a wealth of posts in return, some of which contain some very good information about those things.
Yes, Ford changed those things through the years but I don't remember the specifics.
Yes, Ford changed those things through the years but I don't remember the specifics.
Ford Parts Specialist
Joined: Nov 2006
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From: Simi Valley, CA
1985/86 F100/350: The selector valve could be one of two, as it depends on the number of ports (3 or 6).
Both types have been troublesome turds since day one!
E5TZ-9189-A .. Fuel Tank Selector Valve ~ 3 ports / Marked: E57B-9F271-AA
E5TZ-9189-B .. Fuel Tank Selector Valve ~ 6 ports / Marked: E57B-9F271-BA or E67B-9F271-AA
The selector valves used prior to 1985 and after 1986 will not work!
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Old School Hot Rodder
Joined: Feb 2006
Posts: 6,472
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From: Exmore, VA
First item, the tank vent system does tie to both tanks, then runs along the right side frame rail to the evaporative canister (your truck does still have one?). If the PO removed it and capped the vent line that could explain it.
Second item, 1985-1989 EFI trucks have two or three fuel pumps depending on the number of tanks. The tank selector is a large plastic "can" with 4 ports for 1 tank and 6 ports for 2 tanks. It also serves as a reservoir for the high pressure Bosch pump on the frame rail. NOTE: on 1985-86 models there is a filter inside this reservoir, 1987-89 do not use the filter. If it goes bad, the tanks can do what you describe, it switches tanks based on which low pressure in-tank pump is active.
Second item, 1985-1989 EFI trucks have two or three fuel pumps depending on the number of tanks. The tank selector is a large plastic "can" with 4 ports for 1 tank and 6 ports for 2 tanks. It also serves as a reservoir for the high pressure Bosch pump on the frame rail. NOTE: on 1985-86 models there is a filter inside this reservoir, 1987-89 do not use the filter. If it goes bad, the tanks can do what you describe, it switches tanks based on which low pressure in-tank pump is active.
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FTE Legend
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From: Northeast, OK
I've typed this same info at least two dozen times, here it is again.
1985/86 F100/350: The selector valve could be one of two, as it depends on the number of ports (3 or 6).
Both types have been troublesome turds since day one!
E5TZ-9189-A .. Fuel Tank Selector Valve ~ 3 ports / Marked: E57B-9F271-AA
E5TZ-9189-B .. Fuel Tank Selector Valve ~ 6 ports / Marked: E57B-9F271-BA or E67B-9F271-AA
The selector valves used prior to 1985 and after 1986 will not work!
1985/86 F100/350: The selector valve could be one of two, as it depends on the number of ports (3 or 6).
Both types have been troublesome turds since day one!
E5TZ-9189-A .. Fuel Tank Selector Valve ~ 3 ports / Marked: E57B-9F271-AA
E5TZ-9189-B .. Fuel Tank Selector Valve ~ 6 ports / Marked: E57B-9F271-BA or E67B-9F271-AA
The selector valves used prior to 1985 and after 1986 will not work!
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ok, so I replaced the fuel tank selector valve and that seems to have resolved the issue. We'll see, haven't driven it much yet.
The idiot I bought it from cut the fuel tank switch wires in the dash and spliced two sets together (no idea why), and the fuel pump wires to the front tank at the frame rail and at the tank so I had to rewire everything. Took out both tanks and cleaned them spotless. Tested both in tank fuel pumps and they were both good. Tested the high pressure fuel pump mounted on the frame rail. Got it all back together this weekend and she fired right up like a champ. Ran it for 20 minutes, switching tanks and all seems well.
Thanks everyone for the help! Very much appreciated.
Shane
The idiot I bought it from cut the fuel tank switch wires in the dash and spliced two sets together (no idea why), and the fuel pump wires to the front tank at the frame rail and at the tank so I had to rewire everything. Took out both tanks and cleaned them spotless. Tested both in tank fuel pumps and they were both good. Tested the high pressure fuel pump mounted on the frame rail. Got it all back together this weekend and she fired right up like a champ. Ran it for 20 minutes, switching tanks and all seems well.
Thanks everyone for the help! Very much appreciated.
Shane
Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
Bill - This isn't really just to you. But, do we have a sticky that contains all the tank selector valve info? This seems both a no-brainer and a very useful thing. If we don't have one, what does it need to contain to be most useful? Just saying "Have you done a search" isn't nearly as helpful as pointing to a sticky.
But, both me and you have the parts catalog and can go look it up, I've never felt like taking the time to type out what is already typed (althoug is non-cuttable-and-pastable).
Point me to posts/threads that you guys think contain useful information and I'll add it/them to the Sticky. A PM is probably best, I breeze through stuff in the forums pretty quickly sometimes and don't read everything close enough to comprehend what is being said.
FTE Legend
Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
Or, even easier, why can't we put a page or three of the catalog in a stickie? That's 'cause I fully agree w/you - I don't want to retype what's already been typed and sure don't want to spend my days finding gas tanks, or sending units, or valves in that catalog.