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Thread: Fuel Pump Wires getting hot

  1. #1
    Senior Member lewma's Avatar
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    Fuel Pump Wires getting hot

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    Question on fuel pump wiring. I'm using a Holley 12-132 in tank pump pic below:

    pump.jpg

    I run 12awg wires from the relays to the pump then they eventually meet the smaller gauge wires at the pump.

    Confirmed when the engine is running that 15 amps is being drawn by the pump.

    The smaller wires are very hot after a couple of minutes. So hot that I can't touch them.

    To me, the wires are too small at the pump, but why would Holley produce a pump with that smaller gauge wire ?

    I am using a hydramat inside the tank to suck up the fuel. Could the hydramat be causing the pump to work harder ? But if that was the case, wouldn't the amperage be higher too ?

    Any help from the experts as to why the wires are very hot would be much appreciated!

    mark
    Build 1: Mk4 Complete Kit #9312 Ordered 1/27/18, Delivered 3/24/18, CA SB100 Registered 9/11/19 - Gen 2 Coyote TKO600, IRS, Power Steering, Wilwood Brakes, 17" Halibrand.
    Build 2: Gen3 Coupe Complete Kit #309 Ordered 1/25/21, Delivered 6/9/21, CA SB100 Registered 8/27/24 - BluePrint GM 427 LS T56, IRS, AC, Power Steering. Album Here

  2. #2
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    My Holley came with a little 3x3 hydromat. https://www.holley.com/products/fuel...s/parts/12-345
    I have not run it yet, but I did upgrade the wire gauge for the higher amp draw. Mine also has the small gauge wire coming out of the unit. Although I think that should be sufficient for that short of a run. Seems like something else is going on. This is what Google came up with.

    "A Holley fuel pump wire getting too hot to touch is usually caused by a poor electrical connection, a wire gauge that is too small for the current draw of the pump, a faulty relay, or a failing pump itself, leading to excessive resistance in the circuit which generates heat."

  3. #3
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    I have the same fuel pump, but i have yet to run it. Did you buy a separate Hydramat or did you use the one you get with the fuel pump? I was planning on using the RF harness wires for the fuel pump, but i am glad i ditched that idea and ran a separate thicker wire to the fuel pump..

    Out of curiosity, how did you figure out that the wires are getting very hot? Did you experience fuel pump related issues causing you to investigate?

  4. #4
    Senior Member Kbl7td's Avatar
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    Could be a faulty pump. 12g and 14g should handle 15amps all day.

  5. #5
    Senior Member lewma's Avatar
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    @nick729. I did buy the larger hydramat shaped like a cross the better sits on the bottom of the tank. It connects to the bottom of the pump using a hose. I found the issue when the pump stopped working one day. I pulled the pump from the tank then found that the connectors had melted. I replaced the connector then ran the engine up to test. Within a minute or so the wires at the pump were too hot to touch. I'm thinking there is too much voltage drop from the power source all the way back to the pump via the 12awg wire which is causing too much resistance and heating up the wires. When I get a chance I'm going to run a second power wire to do a quick test. These 450lph pumps pull a lot of amps. I measured mine at 15amps while the pump was running and engine idling.

    I'll report back in a couple of weeks when I've changed up the wiring
    mark
    Build 1: Mk4 Complete Kit #9312 Ordered 1/27/18, Delivered 3/24/18, CA SB100 Registered 9/11/19 - Gen 2 Coyote TKO600, IRS, Power Steering, Wilwood Brakes, 17" Halibrand.
    Build 2: Gen3 Coupe Complete Kit #309 Ordered 1/25/21, Delivered 6/9/21, CA SB100 Registered 8/27/24 - BluePrint GM 427 LS T56, IRS, AC, Power Steering. Album Here

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