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dual fuel tank problem

This is a discussion on dual fuel tank problem within the Classics forums, part of the General Discussion category; I have an 87 swb tbi 350 with dual tanks. my left one works the right one doesn't. I can ...

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    livinhigh
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    dual fuel tank problem


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    I have an 87 swb tbi 350 with dual tanks. my left one works the right one doesn't. I can hear the left fuel pump come on. but when i switch it to the right one i hear nuthing. Is it the switch or the fuel pump. or is anything else i can check. any help would be appreciated.
    2004 Dodge Ram 1500 quad cab. yea its got the HEMI.
    1987 chevy R10. 305 TBI with TH400. Dakota digital gauges. (And yea it smokes the HEMI)


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    <('.'<) (^'.'^) (>'.')>
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    Re: dual fuel tank problem

    does the truck stay running when switched? i beleive the 2 tanks use 1 fuel pump. check too see if you have clogged lines

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    livinhigh
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    Re: dual fuel tank problem

    Quote Originally Posted by trickedout420
    does the truck stay running when switched? i beleive the 2 tanks use 1 fuel pump. check too see if you have clogged lines

    nope it dies instantly
    2004 Dodge Ram 1500 quad cab. yea its got the HEMI.
    1987 chevy R10. 305 TBI with TH400. Dakota digital gauges. (And yea it smokes the HEMI)


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    Re: dual fuel tank problem

    check to see if te valve is actually moving. have someone flip the switch while your under holding it to see if its getting power. then check for plugged lines and i guess check to see if it has a pump

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    Huh? jaredself's Avatar
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    Re: dual fuel tank problem

    My '82 has the same problem but has mechanical fuel pump. I finally got fed up and siphoned out the gas from the right and put it in the left. For sure check the wiring, then the switch, etc.
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    Re: dual fuel tank problem

    an 87 tbi will have a fuel pump in each tank, if you hear nothing when you switch, its probably the fuel pump. I have an 87 LWB 350 tbi and i can hear both pumps running
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    Re: dual fuel tank problem

    It has two fuel pumps on tbi. When mine did that, I took the switch apart and cleaned the contacts (They were corroded and filthy as hell) and put new die-electric grease in it and it worked fine ever since.
    Kenny

    1978 C-20, 350/400, 3.73, Graystone Metallic, Raceline Renegade 8 Wheels - 18x8.5, 275/70R18 BFG KO's

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    Rockin' it old-school! NovaMan's Avatar
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    Re: dual fuel tank problem

    Quote Originally Posted by Porno Joe
    if you hear nothing when you switch, its probably the fuel pump.
    I would have thought the opposite.
    Pete
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    livinhigh
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    Re: dual fuel tank problem

    thanks guys i appreciate it. i guess im gonna check the switch before i drop the tank and change the pump.
    2004 Dodge Ram 1500 quad cab. yea its got the HEMI.
    1987 chevy R10. 305 TBI with TH400. Dakota digital gauges. (And yea it smokes the HEMI)


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    Re: dual fuel tank problem

    well thats good i didnt know it used 2 pumps good info to know for next time. i have a fuel cell mounted in my tool box (20 gallon) and have a holley red pumping it up front. works good and the original fuel tank still works thougt about making some sort of duel tank setup for it.

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    Re: dual fuel tank problem

    i dont have my truck with me to look, but on the tbi trucks, doesn't the power to the pump go thru the valve(so that when you switch tanks the power goes to the other pump)? You might want to try cleaning the connections at the valve to if this is the case
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    Re: dual fuel tank problem

    Quote Originally Posted by NovaMan
    I would have thought the opposite.
    Its just like when you turn on the ignition but dont start the truck, you can hear a fuel pump running in the tank, same thing here, if you switch to the tank and the truck dies, turn the truck completely off and then turn the key to "run" and listen for a fuel pump.
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    livinhigh
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    Re: dual fuel tank problem

    Quote Originally Posted by Porno Joe
    Its just like when you turn on the ignition but dont start the truck, you can hear a fuel pump running in the tank, same thing here, if you switch to the tank and the truck dies, turn the truck completely off and then turn the key to "run" and listen for a fuel pump.

    yep did this and heard nuthing. say i need to check the connection at the valve as well? where might the valve be?
    2004 Dodge Ram 1500 quad cab. yea its got the HEMI.
    1987 chevy R10. 305 TBI with TH400. Dakota digital gauges. (And yea it smokes the HEMI)


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    Re: dual fuel tank problem

    the valve is on the frame under the pass side door
    06 Intimidator SS
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    hucking fates this server FordeatinZ71's Avatar
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    Re: dual fuel tank problem

    before determining that "just because the switch is pushed and the pump isn't running its the FP" you have to first get around the switch (like jumper wire the switch...take the switch out, figure out which wires in the plug do what and jump the one that would make the truck think it's using the right fuel tank...a Haynes manual should tell you this) to make sure it's not just the switch not doing its job. if you jump it and it STILL doesn't come on, then you've narrowed it down to either the pump or the wiring...because if i'm not mistaken the valve just changes the fuel flow...the SWITCH is what activates/deactivates the FPs...i think...lol

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    Re: dual fuel tank problem

    Quote Originally Posted by FordeatinZ71
    ...because if i'm not mistaken the valve just changes the fuel flow...the SWITCH is what activates/deactivates the FPs...i think...lol
    I believe on the tbi trucks, the power for the in tank fuel pump is routed through the switch and the valve, again i'm not 100% on this.
    06 Intimidator SS
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    livinhigh
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    Re: dual fuel tank problem

    yea that was my next move. i was thinkin last night just to try to hook the right fuel pump up direct. thanks again guys. i gonna try that tonight if it dont rain.
    2004 Dodge Ram 1500 quad cab. yea its got the HEMI.
    1987 chevy R10. 305 TBI with TH400. Dakota digital gauges. (And yea it smokes the HEMI)


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    hucking fates this server FordeatinZ71's Avatar
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    Re: dual fuel tank problem

    Quote Originally Posted by Porno Joe
    I believe on the tbi trucks, the power for the in tank fuel pump is routed through the switch and the valve, again i'm not 100% on this.
    yea, i dunno...the only trucks i've personally owned with dual tanks were carb'd. but i have worked on an '89 V3500 crew with dual tanks that messed up...i just can't remember how it goes...a manual with a wiring diagram should clear things up...

    *edit-i looked in my Haynes manual (man those aren't good for crap nowadays are they? i remember back in the day...yea, i'm only 24 but i love old stuff so i collect old manuals/car stuff...when a Chilton's manual was almost the same as a factory service manual...nowadays the manuals SUCK) and it only shows a single tank wiring diagram so i guess you're gonna have to find another source...i'll keep looking

    *edit2-nothing found so far...i'll look again later when i have time or hopefully someone else will come up with something! good luck man!
    Last edited by FordeatinZ71; 10-24-2007 at 09:11 AM.

    2004 GMC Sierra SLE Z71 rcsb, 5.3/4L60E/3.73/G80 time bomb...3" lift, tinted 03+ Silverado tails, plasti-dipped 16" wheels (unknown brand), 285/75/16 Thunderer M/T Extremes, Thrush Welded muffler...

  19. #19
    livinhigh
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    Re: dual fuel tank problem

    thanks. yea i brought my haynes manual with me to work and it does suck. i can't find anything about the switch on the dash nor the valve.
    2004 Dodge Ram 1500 quad cab. yea its got the HEMI.
    1987 chevy R10. 305 TBI with TH400. Dakota digital gauges. (And yea it smokes the HEMI)


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    Re: dual fuel tank problem

    I have the original wiring diagram that came from GM back in 87, unfortunately its at home and im away at school
    06 Intimidator SS
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    87 Chevy 4x4- show truck with NOS
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