How to wire a fuel pump? [Archive] - Chevelle Tech

: How to wire a fuel pump?

Sep 15th, 03, 4:07 PM
How should i wire an elctric feul pump?
Should i use a relay or any type of fuse between it and the toggle switch

Sep 16th, 03, 1:59 AM
Make sure you use a 10 gauge wire or bigger, because the longer the current has to travel the bigger chance of a fire. Mount the pump in the rear, ground it, bring the positive wire up into the car, put the end into a carefully hidden switch (electric fuelpumps are great anti-theft devices). Run another 10 gauge or bigger wire from the other end of the switch under the "Body by Fisher" panels or under the carpet, and bring it behind the driverside kick panel, and out the other side and plug it directally into the fuse block in a "Acc" port and any of the ports that light when the is ignition on. Try to pick a port with the biggest fuse (i.e. 25-30 Amp). For more help, e-mail or keep posting.

Troy Harrison
Sep 16th, 03, 2:47 AM
I noticed you said to "mount in rear." In the car I bought it (fuel pump) is mounted under hood on fender well by the battery. Should I change this? It also does not look like10 guage wire at all, but it does look like it came with this smaller wire. Also, I recently took out the flipswitch for the fuel pump and wired it directly so when I turn key it comes on. (BUT ignition is push button, not key-start). Am I going to explode?

Sep 16th, 03, 8:42 PM

That is NOT how you wire something like a fuel pump! A relay is mandatory, and you don't just use "anything that's hot when the ignition is on". This is a good way for a "meltdown" and/or electrical fire.

I'm not sure what kind of pump you have, but indeed, most I've heard of mount in the rear, closest to the gas tank. You need to run at least a 10 ga. wire from the fuel pump (+) to an under-hood relay. This wire will connect to the #87 terminal position. The #30 position on the relay will go to a fusible link/in-line fuse/or circuit breaker. The other side of your fuse device goes directly to the battery (+) terminal. The #86 position goes to a 16 ga. wire which leads inside the vechicle to the IGN spade lug connector on the fuse box. This is ONLY hot when the car is cranking or running. The number 85 terminal on the relay goes to a another 16 ga. wire that runs inside the vehicle. This connects to a toggle switch. This is your ANTI-THEFT switch. The other side of your switch connects to a good ground. When the switch is ON, the relay will energize when the ignition is on. When the switch is off, no relay activation, thus no fuel pump running = no stolen vehicle.

Connect the fuel pump's ground connection to a GOOD metal ground, preferably on the body. If it gets it's ground thru the pump body unit itself, make sure if you mount it to the frame, it has a good clean metal contact! If connecting any ground to the frame, make sure your run at least a 12 ga. wire from the battery (-) to the actual frame itself to ensure the frame "sees" a good ground source back to the battery (-). Most don't do to rotted or missing ground straps that link the body to the frame.

Troy Harrison
Sep 16th, 03, 9:58 PM
Shazaam! Great info, Wil put relay back in. I am confused however, Is ther eno way to rewire a treet rod so that (with new electronic fuel pump) you simply turn the key and POW it's on? Just like old times. (my ignition is push start, so the ignition key simply turns on my fuel pump and guages). Also, my fuel pump is no-name of fbrand - rinky dink-ish if you ask me, but I am learnign as I go. Thanks a jillion for your commets. I look forward NOT to meltind down. graemlins/beers.gif

Sep 16th, 03, 11:03 PM
One more good idea ? wire the relay ground to a oil pressure switch,the switch will ground the relay turning on the pump when the pressure is over 5 psi.If its not wired this way-in the event of a crash,the engine stalls and the pump keeps pumping :eek: I think you know what happens next.

Peter F.
Sep 16th, 03, 11:16 PM
My idea of an installation would put the relay coil power wire coming from the battery through an oil pressure switch that closes when there is pressure. Then, run another wire from the start terminal on the ignition switch (use the purple wire that goes to the solenoid) to also power the relay coil. That way, when you are cranking the fuel will get to the carb right away but once it's running it needs oil pressure to keep running.