fuel sending unit wiring
#1
04-13-2019, 01:36 PM
Join Date: Apr 2011
Location: Eatonia, SK
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fuel sending unit wiring
First off ill just explain what i have going on.
I put a 1952 Dodge short bed on my 1989 Dakota frame. the Dakota was originally a 3.9l V6 but i ditched that and put a 360 in. I have the mechanical fuel pump on the motor sucking from the return on the original sending unit, witch worked really well.
I want to put a aftermarket fuel gauge in and have the wiring harness separated and am wondering if any of you guys know the wiring diagram or can tell me what each wire goes to.
there is 5 wires and the Grey and Grey/black wire went in the harness to the tail lights then there is Blue/yellow and Blue/red and Green/black wires witch ran to the front.
The plug is round with the Grey/black wire in the center and the other 4 are surrounding it in the plug if that helps
Grey......... Green/black
Grey/black
Blue/yellow....... Blue/red
Thanks in advance!
I put a 1952 Dodge short bed on my 1989 Dakota frame. the Dakota was originally a 3.9l V6 but i ditched that and put a 360 in. I have the mechanical fuel pump on the motor sucking from the return on the original sending unit, witch worked really well.
I want to put a aftermarket fuel gauge in and have the wiring harness separated and am wondering if any of you guys know the wiring diagram or can tell me what each wire goes to.
there is 5 wires and the Grey and Grey/black wire went in the harness to the tail lights then there is Blue/yellow and Blue/red and Green/black wires witch ran to the front.
The plug is round with the Grey/black wire in the center and the other 4 are surrounding it in the plug if that helps
Grey......... Green/black
Grey/black
Blue/yellow....... Blue/red
Thanks in advance!
#2
04-13-2019, 02:08 PM
Champion
Grey 18ga is the gauge ground returns; the gauge sending unit is dark blue/yellow and the low fuel light is dark blue/red. For completeness, the 16ga grey wire is for the pump; the other side is the 16ga dark green/black wire. Those you can actually ignore.
See the attached diagram from my 1988 book.
Addendum: Wire switch 12V to the hot side of a LED, wire the negative side to the dark blue/yellow wire, and presto, a low fuel light! I'd do that; you actually will be using the dark blue/yellow wire to your gauge and be sure to ground well the grey/black wire.
RwP
See the attached diagram from my 1988 book.
Addendum: Wire switch 12V to the hot side of a LED, wire the negative side to the dark blue/yellow wire, and presto, a low fuel light! I'd do that; you actually will be using the dark blue/yellow wire to your gauge and be sure to ground well the grey/black wire.
RwP
Last edited by RalphP; 04-13-2019 at 02:12 PM.
#3
04-13-2019, 06:55 PM
Join Date: Apr 2011
Location: Eatonia, SK
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Grey 18ga is the gauge ground returns; the gauge sending unit is dark blue/yellow and the low fuel light is dark blue/red. For completeness, the 16ga grey wire is for the pump; the other side is the 16ga dark green/black wire. Those you can actually ignore.
See the attached diagram from my 1988 book.
Addendum: Wire switch 12V to the hot side of a LED, wire the negative side to the dark blue/yellow wire, and presto, a low fuel light! I'd do that; you actually will be using the dark blue/yellow wire to your gauge and be sure to ground well the grey/black wire.
RwP
See the attached diagram from my 1988 book.
Addendum: Wire switch 12V to the hot side of a LED, wire the negative side to the dark blue/yellow wire, and presto, a low fuel light! I'd do that; you actually will be using the dark blue/yellow wire to your gauge and be sure to ground well the grey/black wire.
RwP
Thank you sir, I went out and played musical wire and got it figured out, and after reading this i confirmed i got it right.
#4
04-21-2019, 12:07 PM
Join Date: Apr 2011
Location: Eatonia, SK
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So a update, the fuel gauge is stuck on full and i know i have less then half tank as i pulled the fuel neck and dipped the tank. im assuming the potentiometer on the sending unit in the tank is bad.
I hope it isn't as i am not using the actual sending unit but was hoping to get this aftermarket gauge to work off it.
Any tips to check out before i pull the sending unit from the tank and check the potentiometer on the bench?
I hope it isn't as i am not using the actual sending unit but was hoping to get this aftermarket gauge to work off it.
Any tips to check out before i pull the sending unit from the tank and check the potentiometer on the bench?
#5
04-21-2019, 03:55 PM
Champion
What does your after market fuel gauge want for range?
According to the FSM for a 1993 (and the other years are the same!), full is 90 ohms +- 3 ohms; mid range is 45.3 +- 3 ohms; and empty is 12 +- 3 ohms.
The AutoGauge short sweep fuel gauges want either 0-90 (and will read backwards), or 73-10 (and will read FULL to below 3/4 tank at best.)
I'd see what the resistance is on the fuel sending unit now; multi meters accurate enough for this kind of test can be had a Harbor Freight for under $10 (and if you're lucky, free with the coupon!).
RwP
According to the FSM for a 1993 (and the other years are the same!), full is 90 ohms +- 3 ohms; mid range is 45.3 +- 3 ohms; and empty is 12 +- 3 ohms.
The AutoGauge short sweep fuel gauges want either 0-90 (and will read backwards), or 73-10 (and will read FULL to below 3/4 tank at best.)
I'd see what the resistance is on the fuel sending unit now; multi meters accurate enough for this kind of test can be had a Harbor Freight for under $10 (and if you're lucky, free with the coupon!).
RwP