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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: ract1108 on August 21, 2015, 05:58:34 PM

Title: Wiring fuel pump
Post by: ract1108 on August 21, 2015, 05:58:34 PM
I would like to ask a question of all you knowledgeable people out there if I could.  I have an 86 Chevy C 10 with an 87 through 95 350 motor in it.  I have a 5 to 9 psi electric fuel pump that I want to put on my truck because I don't have a provision for a mechanical pump.  I would like to know what gauge wire I should use to wire it.  A friend of mine gave me some 12 gauge audio primary wire with the silicone insulation on it and I wanted to know if that wire would be OK to use, or are the strands in it too thin?  Thanks for any and all input you can provide.


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Title: Re: Wiring fuel pump
Post by: Chuck Step-a-side on August 22, 2015, 07:30:04 AM
What you need is to find out how many amps that fuel pump draws and then google it (For example: what size wire for 8 amps 12 volts?) or find the amperes for the fuel pump and go to this website:  http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html.
Title: Re: Wiring fuel pump
Post by: bd on August 22, 2015, 11:02:25 AM
...I would like to know what gauge wire I should use to wire it.  A friend of mine gave me some 12 gauge audio primary wire with the silicone insulation on it and I wanted to know if that wire would be OK to use, or are the strands in it too thin?...

The AWG Wire Gauge Calculator (http://www.powerstream.com/Wire_Size.htm) is a useful and user friendly voltage drop (wire size) calculator recently linked by timthescarred.  Scroll down below the table.  Set the "Select Voltage" dropdown box to "12 VDC or 1-phase AC" and enter one-half of the anticipated length of the wire run between the power source and the pump (this compensates the calculator for a single power wire, since the chassis/frame will serve as the return ground path).  Enter the posted current draw of the fuel pump.  Now, experiment with different wire gauge sizes so that the "Percent Voltage Drop" window does not exceed 4% (~0.5 v).

Used as a power feed, the strand count of the wire is immaterial and only increases flexibility.  Your concern should be whether the insulation of the wire will withstand abrasion, heat and corrosive road salts.  Automotive applications typically use GXL, SXL or GPT insulated wire for their superior abrasion, heat and chemical tolerance characteristics.
Title: Re: Wiring fuel pump
Post by: ract1108 on August 23, 2015, 03:57:23 AM
That's awesome!  Thanks for all the info


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