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1979 EFI conversion-dual fuel pump wiring

Discussion in 'Electrical & Audio' started by Too much, Aug 14, 2019.

  1. Too much

    Too much Junior Member

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    I have a 1979 K25 and we are about to do an FiTech unit on it. I’ve purchased 87 gas tanks, 87 sending units, aeromotive in tank pumps, the 87 switching valve with its pigtail harness and the 87 switch for the dash. What relay do I use to wire the pumps so they turn on and off when each tank is selected?
     
  2. Frankenchevy

    Frankenchevy Full Access Member

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    Just a heads up to research... 87 switch valve was designed for 10-15 psi pumps. Efi needs approximately 60psi, so hopefully it’s up to the task. I’m not sure, just making sure you are.

    I used a different switch setup altogether. However, I’d assume that the switch has a single power supply 12vdc+ that gets directed to the selected side. If that’s the case, only one relay is necessary on the hot(line) side of the switch. Then it’ll only power up the selected pump.

    Otherwise, the two load sides of the switch can act as triggers for individual relays.

    Sorry I can’t provide pictures. My sniper has a built in relay for the fuel pump, so I didn’t have to do any of this.
     
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  3. Charlie

    Charlie Mopar by Birth. Chevy by Choice.

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    :welcome:
     
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  4. Too much

    Too much Junior Member

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    I bought AC Delco part number U7001. it's rated for 65psi.
     
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  5. C10MixMaster

    C10MixMaster Full Access Member

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    here the 87 diagram. the wiring is different than your 79. if you can get the switch and harness from the later version it will help you might have to make a custom harness. ignore the fuel module part of the diagram but the rest is accurate to your project..

    2011-05-11_023104_pic.gif
     
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  6. Too much

    Too much Junior Member

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    C10, that diagram helps lots! Thanks!
     
  7. 4WDKC

    4WDKC Full Access Member

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    I replaced mine with a newer valve and it said it was rated to 65 psi also.

    welcome, I would wire the relay in the same way the 87 did so it only uses 1 relay and switches the power to the desired tank.
     
    Last edited: Aug 15, 2019
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  8. gmachinz

    gmachinz Harnessworx Inc

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    Or I have factory style conversion kits for this type of swap-with or without an OEM supplied Pollak 65 psi valve.

    DEE55884-EC31-47EB-B567-83CC944542A2.jpeg
     
  9. gmachinz

    gmachinz Harnessworx Inc

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    I prefer to use 2 pump relays so if the event of a relay failure, you can still switch tanks and run on the other to get where you’re going.
     
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  10. Kasey 1977 K10

    Kasey 1977 K10 Full Access Member

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  11. 4WDKC

    4WDKC Full Access Member

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    Does your kit also use an oil pressure switch like the factory setup did?
     
  12. gmachinz

    gmachinz Harnessworx Inc

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    The non-TBI setups did not have the trigger circuit going through an oil pressure switch but I can easily add it to any kit on request.
    Older trucks say...1978-older wouldn’t have the correct pinout for a switched +12V wire for the circuit and/or use a hot air choke or none at all so that cavity is unused in the bulkhead.

    It’s an integration easy enough to add but wouldnt be exactly plug n play since you (the installer)would need to source either empty underhood firewall bulkhead cavities to use (2 wires) and run them from the inside section also to the relay bank which mounts near the fuse panel. I could label everything and you would just need to route them.
     
  13. Too much

    Too much Junior Member

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  14. Too much

    Too much Junior Member

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    Gmachinz, I think you would know the answer to my switch question as well.
     
  15. Kasey 1977 K10

    Kasey 1977 K10 Full Access Member

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    Take a look a the image toward the bottom of the below post. One note, I used power from my sniper efi to power the switch so that if my key is on the pumps aren't running constantly if the engine isn't running. Only during prime.

    http://www.barthmobile.com/eve/forums/a/tpc/f/3431087061/m/4303955787
     
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