How to Direct Wire a Fuel Pump (2-Method Guide)

Fuel pumps are important components in motor vehicles. The supply of liquids or fuels to the carburetor (also known as the fuel injector) is found in the internal combustion engine.

It is crucial to locate the fuel pressure regulator while wiring a fuel pump. I have enough experience in mechanics and I will teach you how to direct wire your car’s fuel pump in less than an hour.

This wiring process is known as the “Fuel Pump Relay Bypass”. You may also want to use a heavy gauge wire in place of the existing one to boost fuel pump performance and the volume of fuel transferred to the engine.

Do you need to direct wire your fuel pump? Yes, you do. If a fuel pump is not wired or installed correctly, it may not transfer fuel to the carburetor. And if the engine doesn’t receive adequate fuel, it won’t work properly.

You should also note that the wiring techniques depend on the length of the wire, its thickness, and the amount of current the fuel pump draws.  In this guide, I will provide a detailed explanation and two methods to use to direct wire a fuel pump.

Quick Answer:

To direct wire your fuel pump, at first, make the connections properly – put your fuse close to the battery. Locate pin 30 on the relay system/circuit.

The pin 30 has a direct connection to the battery. Locate pin 87, it comes from the relay and ends on the positive terminal on the battery. Pin 85 is the ground wire. You can also connect it to the negative terminal on the fuel pump. Pin 86 is a white wire and it is the trigger wire.

The rigger wire will cause the relay to click and turn on the fuel pump. You can hook up a toggle switch and use it to trigger the fuel pump. When you

are upgrading your fuel pump system to a higher volume fuel pump, use a heavy-duty wire. Simply run it from the battery and via the fuse to pin 30 on your relay system. And then run another heavy-duty wire from the relay to the fuel pump.

fuel pump safety switch wiring diagram

Let’s now focus on how you can connect your fuel pump system to the relay and the trigger. And finally, how to direct wire your fuel pump.

Method 1: Wiring a Fuel Pump

fuel pump without wire
Video | ChrisFix

You can wire your fuel pump within the wiring harness and outside the fuel tank. There is no complex or major modification to use this technique. That means you will only take a few minutes to complete the wiring. This is the best method to use as the fuel pump or causation unit is not altered at all. You simply do all the operations on the fuel tank without removing the fuel pump. Let’s check the next fuel wiring technique.

Method 2: Fuel Pump Connection

With this fuel pump wiring technique, you will cut the hot signal wire of the manufactured fuel pump. It is usually black with white strips for 1G AWD. This wire plugs into the fuel pump unit. It is impossible to remove the fuel pump without cutting the hot signal wire. This hot signal wire goes to pin 86 on the relay unit.

The following procedure will help you set up your circuit (The relay and fuel pump are the key components):

  1. Pin 30: Connect pin 30 on the relay unit to the battery of 12V using a wire of a certain color.
  2. Pin 85: This pin goes straight to the ground. Run a wire from this pin to the ground. Note its color to avoid confusion – use different colors for different pins.
  3. Pin 86: This is the hot signal wire.
  4. Pin 87: You may be having wires on your fuel pump due to a lack of a connector. In that case, consider running a wire from the recent aspect of the fuel pump to pin 87.
  5. I also recommend that you run a fuse within the battery feed connections. After the connection, take out the fuel pump. Disconnect the pipe first to avoid kinks and snaps on the hard lines. You need a 19 MM and 14 MM wrench for the lines. Make sure you use the correct wrench. Do not use vice grips. You can face problems.
  6. Next, remove the balmy– 800 MM heads. You may need to lose these studs carefully as they are infamous for snapping.
  7. Now disconnect the fuel pump wiring harness and lift it out cautiously.
  8. You may want to replace the fuel pump with a newer or a larger one to enhance the volume of the fuel pump. If that is the case, you need to get rid of the current fuel pump.

How to Get Rid of the Present Fuel Pump for Upgrade

Take out the fuel pump hanger by unscrewing the screws. And then unplug the fuel pump that’s equipped with a harness. Go ahead and pull the fuel pump nozzle from the causing unit. Take out the pump.

To remove the previous factory fuel pump harness/wiring, proceed as follows:

  1. Locate the causing unit stovepipe. Open the positive/red wire on the stovepipe.
  2. Next, take out the screw which holds the bottom wire on the sending unit. The bottom wire (from the pump) connects to the causing unit via a screw. Strip the bottom wire leaving the screw.
  3. Now drill a hole for the replacement procedure. And then install another wire with a hoop terminal.
  4. To get ready for fuel pump modification, pop off the rubber fastening factor using a flathead screwdriver.
  • You may install a brass bolt via the hole and then employ a brass nut and washer under the hat to attach the fuel pump relay. Go on and connect a wire having a hoop terminal on the topmost part of the bolt head face.
  • Run a wire from the fuel pump via the hole/opening to the relay unit.

Now start wiring up the fuel pump. You may bolt the bottom wire inside the sending unit. While installing new pumps, run a direct wire to the relay unit from the pump. Alternatively, you may cut the fat finish on the sending unit tube. And then use a rubber pipage hose to connect the pump to the sending unit.

Frequently Asked Questions

Should I hardwire my fuel pump?

separating colors for the power wire

Yes, you can hardwire your fuel pump if it is not getting enough current. You may be also wondering if the FP flow varies while running, or it if maintains its constant pressure. Well, it is the manifold vacuum that regulates fuel pressure.

What is the color of the power wire?

The color depends on the car or vehicle model. However, most manufacturers prefer red and black while others may use grey, orange or purple. (1)

What will happen if I wire my fuel pump backward?

Backward wiring will destroy the fuel pump. The fuel pumps chill themselves with the fuel. If they do not receive the fuel, they will die out faster.

Do electrical fuel pumps require a relay system?

fuel pump and a relay system

Well, that will depend on the following factors:

– The length of the wire
– The thickness of the wire
– The amount of current the pump pulls in
– The various types of control on the fuel pump circuit

Your fuel pump system can function normally without a relay unit if there are low current pumps and short circuits.

What gauge wire do I need to use for my fuel pump?

Use 15-inch of 12-gauge wires for your fuel pump. Get 5-inch of 12-gauge wires for the relay power unit, and 5-inch of 14-gauge wires for the ground and trigger. Incorporate mounting hardware and terminals.

What is preventing my fuel pump from getting power?

If your pump or the relay is not getting power then your circuit may be having electrical problems in your vehicle.

There could also be a problem with your switch or the circuit. Discontinuity in the wiring harness alters the flow of current to the circuit components – relay, fuel pump, etc. (2)

Check the continuity of your wires with a multimeter. Also, try to identify connection problems and rectify them.

Take a look at some of our related articles below.

(1) vehicle model –
(2) fuel –

Video References

Ratty Muscle Car


Delphi Technologies

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About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gCertifications: B.E.E.
Education: University Of Denver - Electric Engineering
Lives In: Denver Colorado

Electrical engineering is my passion, and I’ve been in the industry for over 20 years. This gives me a unique ability to give you expert home improvement and DIY recommendations. I’m not only an electrician, but I also like machinery and anything to do with carpentry. One of my career paths started as a general handyman, so I also have a lot of experience with home improvement I love to share.

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