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Thread: Big gauge wires to fuel pump?

  1. #1
    Registered User mad_cow's Avatar
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    Big gauge wires to fuel pump?

    New fuel pump means i needed upgrade wiring.

    Got some 25a wires running to it. Made a hole in the bulk head, just big enough for wires to fit.

    I used a product called dynasteel from supershit. Got told it will work. Sure enought it went all crumbly and didnt hold shit. Try again, or is there a better way?

  2. #2
    Unregistered User Permit Roadsailing's Avatar
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    make the hole bigger and fit a grommet

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    GTFO of my ED doctor ed's Avatar
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    ^^^^ that

    but that said, what wire and why so big for 25A?
    i used 1.5mm^2 wire for my 044 which is good for 15-20A and even at 4 Bar the 044 only pulls 12A or so
    Mit freundlichen Gre

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    Registered User mad_cow's Avatar
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    Might be 20a. The walbro 450 draws 16amps at 50psi @13.4v after almost the factory catching on fire. A bit of overhead is good.

    Grommit was my first thought, what is fuel safe, i couldn't find anything.
    Last edited by mad_cow; 26-11-17 at 03:35 PM.

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    Unregistered User Permit Roadsailing's Avatar
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    Hang on you made a hole in the tank?

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    Registered User mad_cow's Avatar
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    Quote Originally Posted by Roadsailing View Post
    Hang on you made a hole in the tank?

    Lol, in the bulkhead. Where the thing that the fuel pump hangs from inside the tank.

  7. #7
    Unregistered User Permit Roadsailing's Avatar
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    thought by bulkhead you mean firewall, grommet won't do the job you need to do. I would have just put bigger wires on the existing terminals, but as you have a hole you need to fill it with something like this

    https://www.efihardware.com/products...head-terminals

    unless you can get a new flange/plate instead.

  8. #8
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    the type of wire is important too. Not all insulation is suitable for fuel.

  9. #9
    agricultural aerobrick's Avatar
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    efihardware sell those isolated terminals as well as an E85 safe in tank install kit with Teflon coated wire and E85 safe heat shrink. Little pricey, but I found it cheaper than fucking around finding short Teflon coated wire to do the job.

  10. #10
    Ellis Juan mizone's Avatar
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    Quote Originally Posted by Roadsailing View Post
    make the hole bigger and fit a grommet
    Quote Originally Posted by doctor ed View Post
    ^^^^ that

    but that said, what wire and why so big for 25A?
    i used 1.5mm^2 wire for my 044 which is good for 15-20A and even at 4 Bar the 044 only pulls 12A or so
    Jayvcar or Altronics have these dirt cheap.


    Clean the drilled hole with a file to stop it from cutting, paint to stop rust.

    If the wire is really big, use a cable glan. Again any electrical shop will have these, MM, Jaycar, Altronics etc.


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    Fwiw I just did a 4m run with 25a cable not for a fuel pump but the load is 260w so @12v 21.5amp I get .9v drop with a battery terminal voltage of 13.8 (of course that is with the alt charging no load is 14.3v). The wire is https://www.jaycar.com.au/red-25-amp...metre/p/WH3080 I worked it out to be near equivalent to 13 AWG. On a big pump motor drawing 16amp with probably 5-6m run of 20amp rated wire I can see massive voltage drop under inductive load when the motor is starting up which is what gets wingdings hot.

    Edit it says 12 AWG in the specs but that is incorrect according to the charts I looked up it more like a 12.5.
    Last edited by S; 27-11-17 at 07:05 AM.

  12. #12
    Registered User mad_cow's Avatar
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    Quote Originally Posted by Roadsailing View Post
    thought by bulkhead you mean firewall, grommet won't do the job you need to do. I would have just put bigger wires on the existing terminals, but as you have a hole you need to fill it with something like this

    https://www.efihardware.com/products...head-terminals

    unless you can get a new flange/plate instead.
    Thanks! This is the type of thing i was orginally looking for. Couldnt find them when searching. Ill have to order a couple.

  13. #13
    \_(ツ)_/ burn is weird's Avatar
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    don't run fuel wires through a tank boundary. the fuel will wick up through the wire strands due to tank vapour pressure and capillary action and you'll get fuel smell outside the tank over time.

    you need to use a proper bulkhead fitting that provides a gas tight seal. either hermetically sealed pin fitting or those pass through bolts as above.

    I used 12GA Tefzel wire on mine so if I ever need to go to a bigger pump I don't have to touch the wiring and it wont swell/break down from fuel/E85. good for 25a but will take 35a for short bursts if you're using a pump controller.
    Last edited by burn is weird; 27-11-17 at 09:31 AM.

    Oo___oO


  14. #14
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    I used 8mm wire from the battery with a 80a circuit breaker to the back of the car to a Cole hearse continuos duty solenoid next to the fuel tank.
    Then used an Aeroflow(yuck) bulkhead electrical terminal drilled out for an 8mm stud.
    Runs two walbro 460s at about 75psi with no issues.
    Was running a efi hardware bulkhead terminal but it got melty and touched the pump hanger.

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