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Pickup tank switcher questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dremu, Aug 7, 2004.

  1. dremu

    dremu Officious Thread Derailer Premium Member

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    Working on a '74 /forums/images/graemlins/crewcab.gif. There are two tanks, connected to a central switching device, which is mechanical, unlike the newer ones which are apparently electric.

    This one seems to actually have two switching units, activated by a single pushpull cable much like a throttle cable. Presumably one is fuel feed and the other the return? There's a maze of hoses up there in the frame rail and I didn't take a lot of time to sort it out.

    I'm curious as to how much play the throttle cable-like gizmo that drives this switch is supposed to have; seems like less than, I donno, a half an inch and less than a quarter of a turn is required.

    Doesn't help that the PO disconnected all kinds of wires /forums/images/graemlins/angryfire.gif apparently not understanding electricity, so I gotta trace the auxiliary float wiring and see where it got broken /forums/images/graemlins/frown.gif ... until then I've no idea how much gas is in tank #2, to tell if it's getting used or not.

    Suppose I could just run tank #1 dry and hope /forums/images/graemlins/laugh.gif

    Anyway, anybody who has seen these early mechanical fuel switch things and can tell me anything about them, please speak up.

    Anyone who says "replace it with the electrical" is welcome to come out here and do it for me. /forums/images/graemlins/histerical.gif

    Edit: Neither the Chilton's nor the factory manual (Helm) mention this damn thing... or at least I'm wookin pa nub in all da wong pwaces. Anyone with the Helm manual feel free to correct me!

    -- A
     
  2. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    I do not think that is a stock valve. Those valves were famous for failing, what you describe is probably an aftermarket valve that was available in the 70's or something.
    I have a full GM Parts book for '73-78 as well as the '73 and '75 HELMs service manuals, and it lists the valve as electrical for all '73-78 trucks, I don't have the books for later years.
    I had dual's on an '75 pu I used to have, and it had an electrical one.
    I just added the second tank to my '86, I used an aftermarket elec. valve.

    I've never seen a mechanical version....does it not work or is there a problem with it?
     
  3. dremu

    dremu Officious Thread Derailer Premium Member

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    oh lordie. Didn't think about aftermarket. It's nice, then ... has a plate for the pull cable that goes in the factory location and LOOKS original.

    Umm, I can't tell if it's working or not ... PO had removed the fill hose for the aux tank, and apparently did something with the sender wiring... so I'm sorting out, one piece at a time, how Things Should Be.

    If this thing outsmarts me or is dead, do you have a recommend for an aftermarket valve?

    -- A
     
  4. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Ok, I was wrong. I'm a bad looker...
    Parts book lists: Group 3.164

    73-74 C-1,2,3 (Cab) w/auk tank (454) 338611 Valve ASM, auk fuel tank selector (Man)

    then

    73-77 C-1,2,3 (Cab) w/aux tank (exc 454)
    73-74 K-1,2 (Cab) w/aux tank
    75-77 K-1,2,3 (Cab) w/aux tank (exc T.H.) 334577 Valve ASM, aux fuel tank selector (elec)

    And a couple other elec ones throuh 78

    So the manual valve is only C trucks with 454 for years 73-74! As you say, GM is silly!

    The 73 helms does not mention the valve at all, the '75 one does, but only for fuel drain safty techniques, when replacing, and of course by 75 they were all elec, according to the parts books.

    Sorry about that..
     
  5. dremu

    dremu Officious Thread Derailer Premium Member

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    Ah, no worries. I didn't think to dig through the parts books yet ... donno if I have a 73-74, though, might just be '77 for the Chalet. /forums/images/graemlins/dunno.gif

    Thanks for the info; this gets me closer, anyway.

    -- A
     
  6. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    I used a Borg Warner FSV2A , it has six ports, 1 ea. for return and feed in from each tank, and 1 out return and feed, the vent line is just tee'd.
    On my old '75 I used a different brand that operated just like OEM. This BW one is way better, it actuates based base on polarity from the switch.
    The OEM operated the aux tank only under power. So if you ran the main tank dry, and were operating on aux, when you shut the truck off, the valve would revert back to main, until you throw the ignition again, works ok, but if you weren't paying attenetion, the truck wouldn't start until you left the ignition on for about 10 seconds. This BW valve takes only milliseconds to switch, and it's permenatly in a position until the switch is thrown again, so if you switch to aux, it stays in aux regardless of whether the valve has power or not. The OEM required power all the time to operate aux tank.

    Anyhow, that BW swtich was like $50, the oem type one was $45, in a 6 port configuration, if you don't have/need a return line, then you only need a 3 port one. I'd stay away from those generic 3 port ones, I run through 3 of them on my '75 before I bought a name brand that worked until I sold the truck. I think I saw my save BW switch in a 3 port config, and it was like $35 ..I hope your friends with your auto parts store guys, they couldn't find any, and I poured through thier books for about an hour to come up with the one I got. the key words are 'Fuel Tank Selector Valve' or 'Valve - Fuel Tank Selector'

    I'd help you do it if I lived anywhere near CA, but alas, I don't. I'm in Michigan. Like I said, I just did my '86 daily driver a couple of months back..I even fabbed in a long tube under the bed and a second filler neck in the wheel well, so both my filler necks are on the same side. (And I didn't have to cut a hole or by a new bed!)
     
  7. dremu

    dremu Officious Thread Derailer Premium Member

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    No worries -- thanks for all the info!

    If you have the illustrated parts manual to go with the parts catalog -- I just dug mine out /forums/images/graemlins/smile.gif -- you can see the gizmo in question.

    Seeing as mine has six ports, I assume I'd need to replace it with a six-port one as well. Considering that GM wanted $122 for the switch in 1984, god only knows what they'd et for it today, if it's still available.

    And I don't even know if it's bunged yet /forums/images/graemlins/smile.gif

    Thanks again!

    -- A
     
  8. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Your book should be the same or similiar as mine, it was published in April 1979 and covers 1973-1978 models.

    Here's a couple other numbers for you

    338615 73-74 C-1,2,3 (454) Bezel aux fuel tank selector switch. Bezel should read "Fuel Tank - Push RH Pull LH"

    338612 73-74 C-1,2,3 (2dr) (454) Cable ASM, fuel tank selector switch
    338613 73-74 C-1,2,3 (4dr) (454) Cable ASM, fuel tank selector switch

    326585 73-74 C-1,2,3 (454) Knob ASM fuel tank selector cable
     
  9. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    But WHY only 2wd trucks with 454!!!!????? Why!!!
    I see it, wow..

    If you need the 6 port model, go for the Borg Warner FSV2A
     
  10. dremu

    dremu Officious Thread Derailer Premium Member

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    "1973-78 Truck Parts Catalog / Light Duty Models Series 10 thru 35", February 1984, #51, and companion "Truck Illustration Catalog", same date, #51A.

    T3-2 has the picture of the clusterhork /forums/images/graemlins/laugh.gif

    -- A
     
  11. 84_Chevy_K10

    84_Chevy_K10 Banned

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    You can get your supposed $122 valve at Autozone for less than half that.

    Wells makes it. Have your favorite counterman/woman open up the catalog and look up a fuel selector valve.
     

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