Ls wiring

Discussion in 'High Tech Retrofits' started by Goat, Mar 15, 2017.

  1. Goat

    Goat Veteran Member Lifetime Gold Member

    1,813
    28
    Jun 7, 2001
    moncure, NC
    You're not being a pain. I just got through wiring up my 70 with the same kit you have. Your kit must be a little newer though. The "fuel" wire in my Painless kit is pink and 14 gauge. Just to clear the air, in the manual it says to hook that wire up directly to the fuel pump. There is no mention of a relay. That wire comes directly from the fuse box and uses a 15amp fuse. Obviously, if your pump (or any other one) pulls more than 15 amps, it would not be wise to use that wire.

    Having said all that, if you are currently running your pump with the painless 12 ga wire, it must be ok. However, I do agree that using the ecm to control the pump is a better option. I am still a little confused on the "14-16 gauge wire" in the GTO harness. It appears to me, from the way it is presented in the diagram, that it is the intended hookup wire for the pump. Maybe the pump in the GTO did not pull a lot of current...

    BTW, that kit is awesome. The manual is well written and the pictures are very helpful. Read it several times as you go through your project. Also, there are several 'wires' that you will not need. I used many of the "switched" wires that I didn't need to power other things I have added. It makes it very convenient because you already have the wires running through a fuse box. I also have the Vintage Air kit, Dakota digital dash and a few other systems that require power hook-ups.

    If you have any questions I can answer, feel free to pm me...
     
    Last edited: Oct 18, 2018
  2. GDSmith

    GDSmith Member

    37
    5
    Aug 4, 2012
    Glen Ellyn, IL
    As soon as I figure out how to pm.

    This is a Tanks EFI system with the GPA2 pump, when installing pretty sure the instructions call for using a 12 gauge power feed with a 30amp fuse / relay.
    While re-reading the power requirements of the pump at 60psi is 7.6 amps. I also reviewed the Painless circuit identification and on page 158 is noted the pink fuel 15amp fused pink wire which is also 14 gauge. With all that said is the wire connection from the ECM (14 gauge) an option? This is where I am losing it, conflicting information, hence the reach out.
    Thanks for your patience!
     
  3. badazz81z28

    badazz81z28 Veteran Member

    14,945
    189
    May 4, 2001
    Las Vegas, NV
    Yeah the wire size does depend on the pump. The painless harness is set up for a electric fuel pump on a carb engine. With the LS the ECM controls the pump. It will only allow the pump to operate when the engine is running. It’s a safety feature really and honestly you theoretically could wire it straight to it. But I wouldn’t.
     
  4. linenoise

    linenoise Veteran Member Lifetime Gold Member

    159
    3
    Apr 17, 2000
    CO
    Great info, does the feed for the fuel pump that comes from ecu and controls relay work on duty cycle or on/off only? So that if your at a light at idle it runs the pump with less cycles than if your stomping on it. I am told it does but Detroit Speed and just use a feed from the ecu and relay and it will scale duty cycle with need. They say the only reason to get a controller is if you do not have a ECU with fuel power output lead (like when we run a Carb). Anyone know if this for sure is the case? I plan on running with this method and see. if not I will add a aeromotive Billet Fuel Pump Speed Controller later to keep the pump working longer and keep less noise from pump when sitting idle.
     
  5. 71RS/SS396

    71RS/SS396 Veteran Member

    2,607
    22
    Aug 26, 2008
    Wake Forest NC
    You need a pulse width modulated controller and an inline pressure sensor for the pump to run based on demand. Vaporworx sells controllers with the pressure sensor to do this. I've been using one of their controllers with a CTSV pump for 6 years and it's been flawless.
     
  6. badazz81z28

    badazz81z28 Veteran Member

    14,945
    189
    May 4, 2001
    Las Vegas, NV
    ^ yup, my ECM controls the relay to operate the pump. My PWM from Vaporworks along with its pressure sensor controls the pump rate. The new cars do have these built in but I’m not familiar with the wiring or the controls.
     
  7. GDSmith

    GDSmith Member

    37
    5
    Aug 4, 2012
    Glen Ellyn, IL
    FOUND IT!!!
    Found the elusive relay, when the body guy put the motor controls back there was an relay with a piece of tape on the back side of one of the relays marked “F”. Turned the key on w/o starting the engine and it was active for about 3 seconds.
    Thanks everyone for your patience.
    Onto the next wiring headache.
     

    Attached Files:

  8. linenoise

    linenoise Veteran Member Lifetime Gold Member

    159
    3
    Apr 17, 2000
    CO
    I got the CTSV pump too. ok sounds like I do need the PWM vaporworks than. Thanks guys.
     

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