Electric Fuel Pump Wiring

[twmattox]

Just a couple quick questions:

1) all the people on here talk about running it through a relay. The fuel pump only pulls 1.5 amps... Why run it through a relay?

2) My GW is an '88. These came with that late model ignition solenoid (more like a relay box without the relays). When I wired up my MSD, I just found a space on one of the studs that was energized when in the on position. Was planning on tying my fuel pump to the exact same place (obviously through a 10amp fuse). I am using 16 gauge wire (what I have on hand) which is rated to much higher than 10amps (given my length of run, 16 gauge is rated at closer to 20 amps).

3) What am I missing???

[Heimeken]

The relay is a matter of choice and ease of troubleshooting.

I run mine on a relay, triggered from the oil pressure switch. That way the pump only works when the engine is turning.

[Tinkerjeep]

The only problem with that idea is that now you cannot pre-prime the carb with fuel without also cranking the engine over. That's the main reason I run an electric fuel pump on all my Jeeps -to preprime the carb without having to crank-crank-crank the engine when cold. And the bonus is, when the key is in the Start position and the starter is cranking the engine, the fuel pump kicks out because its wired through the "run" position. Once it catches, it all runs together in harmony.

My answer - wire the fuel pump feed wire to a "run" position feed somewhere and use the best wiring you can to the battery for the ground. Do not run ground to the chassis as the connection will corrode and you'll get stuck with no fuel pump due to bad ground. I run 14 or 12 gauge for this stuff. You don't need a relay, its one more $8 part and twice the wiring for no gain. Make sure all your connections are well made - No crimp-butt-splices. No spade-connectors. Solder that line and insulate it good.

[Tripwire]

Agree with Tinker... direct connections no breaks to the run and to the battery ground, put a quality toggle switch inline somewhere so you can make it anti theft...... use rubber insulators on the frame to minimize vibration noise, be sure to put the pump as close to the tank as possible but out of the way of road debris and put the filter on the pump inlet - not the outlet

[serehill]

Pretty simple

Like everything else the relay carries the load instead of the ignition system. It allows you the ability of running less load on the ignition switch & circuit that was not built to run it. It also allows you to run an oil pressure controller is you wish. Motor load especially 100% duty cycle can strain the ignition circuit. I have all of my motors relayed. I don't run the oil pressure controller. You can also run a rollover controller that allows you to shut the fuel pump off in the event of a roll over. When I turn my key on with the relay the fuel pump fires right up & pumps fuel. Because it's wired correctly. I don't understand that you have to crank the motor deal. Then it starts without a bunch of cranking just like there was no relay. Cranking the engine. It's not magic LOL. Relay on when the key turns on pump comes on pumps fuel then hit the key boom. The pump does draw 1.5 with no load under pressure it draws more if you have any kind of decent pump. If you have one of those little toy ones then you probably don't need one. My ignition & fuel pump run off the same relay. it simply ensures low load on your 30 year old ignition system & full voltage to the pump. Mine also has the relay looped into the burglar alarm so it won't fire or pump fuel if someone decides to steal it. You can live without it. You can live without lots of other things but there's advantages.
Do you have to no. It is more trouble free yes. Chances are also I get better voltage which adds life to the motor. If the relay is wired properly.

[joe]

Do you have to no. It is more trouble free yes. Chances are also I get better voltage which adds life to the motor. If the relay is wired properly.

Agreed. With only A 1.5A draw, not mandatory but for 6 bucks and a bit of wire, why not.

[mark]

i used to run it on a relay.but had problems with the relay itself getting wet and running all the time.(my relay is underneeth my rig).
this time i just put it right to the wire i used to trigger the relay.
definately ground it back to the battery.i had nothing but problems before i did this.

[serehill]

Better mouse trap

Put the relay under the hood or under the dash. Far simpler a lot less wiring NO issues. It's always good practice to not terminate or have connections exposed under a vehicle. There's no real reason to do so. Run the ground to a clean spot. I don't frame ground anything.

Just to be clear with the manufactures recommended wiring even though it's stated this pump only draws 1.5 amps look at Holley's requirement for the pump electrically. This is real world & what you should protect you motor with. It's a known fact that motors at start up lock rotor can draw 225% of it's rated load. It's only for a few seconds but longer under pressure. a 1.5 amp circuit or fuse would be too small. That is fact. It's hard on a weak circuit. The facts show to protect the pump with a 7 1/2 amp fuse. Fuse it for 1.5 amps or wire it that way expect issues. Electrical issues with a fuel pump can't be good.

•Tumble polished billet look
•Lower housing casting designed for enhanced fuel flow and quiet operation
•Maximum pressure is 7 psi
•Motor draws 2 amps current
•7 1/2 amp fuse recommended
•Constant fuel flow with no pulsation