The fuel pump has quite a few connections to it. There are essentially 6 different colors you need to look at. Each one is denoted by a different color code. I will cover below fuel pump wires’ color codes so that you know right away how the connections are made.
Fuel pump wires color codes
1. Green and yellow:
The green and yellow colors refer to the connection between the fuel pump and the inertia shut-off switch. When you’re replacing the fuel pump, you need to use this color for the same.
The White/Black combination connects the power source to the inertia switch. The black, in turn, connects it to the ground. In some cases, however, White is replaced by pink. If you want to depict this connection, you need to use the White/Black combination.
3. Blue and green:
The blue wire and the green wire color code are used separately. However, both of them are connected to the low warning lights. If the fuel is low, these are the wires that will pass the signal to the respective lights.
4. Light blue:
In a way, light blue is one of the most significant ones. That is because it is connected to the fuel gauge.
All references to the ground are colored using black. That is why, whenever you see a black color, it is easy to understand that it has the ground components and the circuit.
The black/red wire indicates a fuel level sender negative. Out of this combination, the red is specifically for the positive.
Watch this video for gm fuel pump wiring!
Is the color code different for different brands?
The good news is that almost all the manufacturers (gm, ford, chevy, jeep and dodge ram) use the same wires color codes. The color code is similar whether you have a newer or an older model.
At the most, one or two colors might be different from that I have highlighted above.
What happens when you wire a fuel pump wrong?
With so many connections, it is indeed possible that you might connect the fuel pump in the wrong way. Wondering what will happen in that case?
1. Won’t work:
In most cases, when you wire it wrong, the fuel pump will not work at all. When the fuel pump is not working, no fuel will be supplied to the engine.
Consequently, your vehicle won’t start at all. That is why you will have no other option but to remove the fuel pump and wire it correctly.
2. Doesn’t supply enough fuel:
In some cases, the fuel pump might still work. However, it won’t be able to provide the proper amount of fuel to the engine.
In most cases, the engine might start, but your vehicle might not. In that case, the engine will not be powered appropriately, and you won’t be able to your vehicle beyond a certain speed.
If you encounter any of these problems in your vehicle after changing the fuel pump, it indicates a wrong connection, and you need to reconnect the fuel pump.
How do you test a fuel pump wire?
Even though a few symptoms indicate that the pump might not be connected properly, at times, you might want to check the same. The steps that I will highlight below will help you out.
Step 1: Connect the multimeter:
The first thing you need to do is connect the multimeter to the fuel pump. You have to connect the multimeter to the fuel pump’s positive and negative terminals.
You need to ensure that the prongs of the multimeter are in direct contact with the terminals of the fuel pump.
Step 2: Switch on the ignition:
The next tip is to turn on the key in the ignition slot. However, you shouldn’t turn on the engine. You will be able to hear a swirling sound from the fuel pump.
The sound indicates that the fuel pump is going to provide fuel to the engine. During this time, the readings on the multimeter will let you know if it is working properly or not.
In case, the voltage reading is false or below normal; it indicates that the fuel pump is not getting enough power.
Step 3: Test the negative terminals:
After that, you have to divide the circuit. On one side will be the ground. On the other will be the positive side. With the help of jumper cables, you have to fuel the pump.
After that, connect the multimeter to the pump and the battery. This should be done on the negative terminals.
If the reading is higher than 0.1, there is a voltage loss. The loss can be due to wearing on connector ends.
Step 4: Test the positive terminals:
Now you have to repeat a similar test of all the positive terminals of the battery. The digital multimeter should be connected to the pump and the battery on the positive terminals.
Similarly, test the voltage to ensure that the reading is not more than 0.1 V. In case the reading is greater than 0.1V; the problem is with the wire.
After that, you will have to diagnose which wire is not functioning appropriately.
Step 5: Test the relay:
While you are at it, it also makes sense to check the fuel pump relay. For the same, you will have to remove the relay.
Similarly, start the ignition without starting the engine. After that, connect the multimeter probes to the relay connector. As highlighted in the step above, you have to check the voltage and determine if the relay is proper or not.
Step 6: Test the pump:
In the last step, you will be testing the pump itself. You have to remove the pump from the vehicle. After that, connect the multimeter to the jumper wires connected to the battery. When you similarly measure the voltage, it becomes really easy to test the pump.
With the help of the procedure above, you can test the wires in the fuel pump and the relay in the fuel pump in its entirety. Once you perform this test, it will be easy to understand whether the problem is with the wires, relay, or fuel pump.
In the procedure above, you have to connect the multimeter probes to the positive terminal and the negative terminal of the fuel pump. However, which one are these?
Are these denoted by any color?
We will answer this question below.
What color is positive on the fuel pump?
Usually, positive is denoted by the darker brown color. The small nut is usually the positive one. There is even a symbol of + on the positive terminal of the fuel pump.
That is why; it is really hard to mistake one for the other.
Similarly, the negative one has a large nut. It also has the symbol -. Apart from this, it is light brown in color.
Once you keep these factors in mind, it is effortless to spot the fuel pump’s positive and negative.
What is the purple wire on a fuel pump?
The purple wire, if present, indicates the water supply to the relay. It is usually derived from the loom to the relay and then to the fuel pump.
Can you connect the fuel pump straight to the battery?
Yes, you can connect the fuel pump straight to the battery. To do the same, you need to connect it to the battery’s positive terminal.
Tips to avoid while connecting a fuel pump:
1. Not replacing the fuel filter:
Most automobile owners focus on the fuel pump. While they might replace the fuel pump in the older cars, they do not replace the fuel filter.
In case the fuel filter is not functioning correctly or is clogged, it will kill the fuel pump once again. That means you will have to replace both the parts again. This will not only lead to time wastage but also unnecessary expenses.
2. Choosing the wrong gasket size:
Whenever you’re installing a new fuel pump, you need to also install a new gasket. Instead of using a gasket of the universal size, it is a good idea to use one specifically designed for that particular car.
That is because if the gasket is too big or too small, it will pass air into the fuel tank, and that will interfere with the working of the fuel pump. It will result in an erroneous code, which will require fixing.
3. Not taking care of the fuel tank and removing it:
During the replacement procedure of the fuel pump, it is really common to remove the fuel tank as well. However, if there is a buildup of debris in the fuel tank during that time, the fuel pump will not work properly. It will lead to the clogging of the fuel filter and the pump itself. That way, the fuel pump is likely to fail once again.
That is why, if at all you are removing the fuel tanker while replacing the fuel pump, you have to ensure that no debris accumulates in the fuel tank.
Once you follow these three steps while installing a new fuel pump, you will be able to install it appropriately and ensure that there is no other problem.