How to Connect the Fuel Pump to the Ignition Switch (Guide)
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If you're a mechanic lover like me, the thought of replacing a mechanical fuel pump with an electric fuel pump got you excited. Even if most people don't get it, I can't blame you for getting excited, we're only human.
Without a doubt, electric fuel pumps perform much better than old-fashioned mechanical fuel pumps. In my personal experience, installing a new fuel pump is easy. But the wiring part is a bit tricky. Connecting the relay contacts in the right place requires the appropriate knowledge. So, today I hope to introduce you to how to properly connect the fuel pump to the ignition switch.
Generally, to connect an electric fuel pump, follow these steps:
- First, turn off the engine.
- Ground the negative terminal of the fuel pump and terminal 85 of the relay.
- Connect terminal 30 to the positive battery terminal.
- Connect terminal 87 to the positive terminal of the fuel pump.
- Finally, connect pin 86 to the ignition switch.
That's all. Now you know how to connect a car's electric fuel pump.
Upgrade Options
There are two different upgrade options depending on your requirements. So let's check them out.
Option 1 is to keep both mechanical and electric fuel pumps.
If you plan to keep the mechanical fuel pump as a backup, place an electric pump next to the tank. This is not necessary as electric pumps are very durable.
Option 2 - Remove the mechanical fuel pump
In general, this is the best option. Remove the mechanical pump and replace it with an electric pump. Here are some simple steps.
- Loosen the screws holding the mechanical pump and pull it out.
- Apply protective gasket and sealant to the hole.
- Install an electric pump next to the fuel tank.
- Install the filter next to the electric pump.
- Complete the wiring process.
Things You'll Need
Here are some of the things you will need to complete the electric fuel pump connection process.
- Suitable electric fuel pump (Must match the year, model and make of your vehicle)
- Wires of the correct gauge (use at least 16 gauge)
- Blocking plate gasket
- Sealant
- Fastening for the automobile electric fuel pump
Wiring diagram
As I mentioned, the most difficult part of installing an electric pump is the wiring process. If you do everything right, your car will have an excellent fuel priming system that works flawlessly. Plus, given the long life of electric fuel pumps, you won't have to change them for a long time. With that in mind, here is the electrical fuel pump wiring diagram.
Tip: Use at least 16 gauge wire for this connection process.
As you can see, all the elements on the diagram are labeled. You should be able to understand the circuit without too much trouble if you are familiar with electrical circuits. However, I am going to explain each point.
Electric fuel pump
The electric fuel pump has two posts; positive and negative. You must ground the negative post. Connect the negative post to the vehicle chassis. I will explain the connection of the positive post with the relay.
12V battery and fuse
The positive battery terminal is connected to the fuse.
Why use fuses
We use a fuse as protection against higher loads. The fuse has a small wire that melts quickly if the current is too high.
Relay
Most often, relays come with 5 contacts. Each pin has a function and we use numbers like 85, 30, 87, 87A and 86 to represent them.
What is 85 on the relay
Typically 85 is used for ground and 86 is connected to a switched power supply. 87 and 87A are connected to the electrical components that you want to control with a relay. Finally, 30 is connected to the positive battery terminal.
So for our electric fuel pump
- Ground terminal 85 using the vehicle body or any other means.
- Connect 87 to the positive terminal of the electric pump.
- Connect 30 to the fuse.
- Finally, connect 86 to the ignition switch.
Keep in mind: We do not need pin 87A for this connection process.
Common Newbie Mistakes to Avoid During Installation
While electric fuel pumps are very reliable, improper installation can damage the fuel pump. So, avoid the mistakes listed below by all means.
Installing the fuel pump away from the fuel tank
This is a common mistake that most of us should avoid. Do not install the pump far from the fuel tank. Always keep the fuel pump close to the tank for maximum performance.
Installing the fuel pump near a heat source
It is never recommended to install the pump and fuel line near a heat source. Therefore, keep the pump and line away from heat sources such as exhaust. (1)
No safety switch
When you're dealing with a fuel pump, having a kill switch is a must. Otherwise, if the fuel pump malfunctions, oil will begin to leak everywhere. To avoid all this, install an oil pressure sensor. (2)
Take a look at some of our articles below.
- How to test a fuel pump with a multimeter
- How to test a 5-pin relay with a multimeter
- How to connect a fuel pump to a toggle switch
Recommendations
(1) heat source - https://www.sciencedirect.com/topics/physics-and-astronomy/heat-sources
(2) pressure switch - https://www.sciencedirect.com/topics/engineering/
pressure switch
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