How to replace the fuel pump relay

The fuel pump has a relay that fails when there is no audible buzzing when the ignition is turned on and when the car takes longer than normal to start.

The fuel pump relay helps your car start the car by pressurizing the fuel system for the first few seconds before the oil pressure level comes into its own. The fuel pump relay is usually found in the car's long black box, along with other relays and fuses. However, the location may be different in some other vehicles.

Without this relay, the engine would not receive fuel when starting. The pump that supplies fuel to the engine while it is running requires electricity to operate. This electricity is generated by the oil pressure device in the engine. Until oil pressure is built up, which in turn generates electricity to run the fuel pump, the pump cannot deliver fuel to the car's engine.

When the ignition of the car is turned on, the magnetic coil with an open contact is activated; the contact then completes an electrical circuit in the electronic mechanism and eventually the fuel pump relay is activated. When the vehicle ignition is turned on, the pump relay makes a humming sound. If this sound is not heard, it may indicate that the pump relay is not working properly.

When this relay fails, the engine will start after the starter has built up enough oil pressure to energize the fuel pump and start it. This may cause the engine to start longer than usual. If you don't hear the fuel pump hum, but the car eventually starts and runs fine, the fuel pump relay has failed.

If the fuel pump relay fails, the engine management system records this event. The fuel pressure sensor tells the computer if the fuel pressure is not creating any pressure during engine cranking.

There are several engine light codes associated with the fuel level sensor:

P0087, P0190, P0191, P0192, P0193, P0194, P0230, P0520, P0521, P1180, P1181

Part 1 of 4: Removing the Fuel Pump Relay

Necessary materials

• Pliers with needles
• Ratchet with metric and standard sockets
• Wheel chocks

Most fuel pump relays are located in the engine compartment inside the fuse box.

Step 1: Turn on the ignition key to start. Listen for the operation of the fuel pump.

Also, listen to the fuel pump relay for a buzz or click.

Step 2: start the engine. Check if there is oil pressure.

Some vehicles will only have an oil level indicator. When the indicator goes out, it means there is oil pressure.

Step 3: Park your vehicle on a level, firm surface.. Make sure the transmission is in park (for automatic transmission) or 1st gear (for manual transmission).

Step 4: Install wheel chocks around tires.. In this case, the wheel chocks will be located around the front wheels, since the rear of the car will be raised.

Apply the parking brake to block the rear wheels from moving.

Step 5: Install a nine volt battery in the cigarette lighter.. This will keep your computer running and save the current settings in the car.

If you don't have a nine-volt battery, no big deal.

Step 6: Open the car hood to disconnect the battery.. Remove the ground cable from the negative battery terminal by turning off power to the fuel pump and transmitter.

Step 7: Locate the fuse box in the engine bay.. Remove the fuse box cover.

• Attention: Some fuse blocks are attached with screws or hex bolts and require a ratchet to remove them. Other fuse boxes are held in place by clips.

Step 8: Using the diagram on the fuse box cover, locate the fuel pump relay.. With the fuse box open, you can use the diagram on the fuse box cover to locate the fuel pump relay fuse.

Step 9: Remove the fuel pump relay from the fuse box.. Pay attention to how the relay comes out as the new one should go exactly the same.

Also, if there are no diagrams on the fuse box cover, you can refer to the owner's manual for a diagram of the fuse box in the engine compartment. Usually in the owner's manuals, the numbers are listed next to the fuel pump relay so you can find the number on the fuse box.

• AttentionA: You may need to use pliers to pull out the fuel pump relay.

Part 2 of 4: Installing the New Fuel Pump Relay

Necessary materials

• Replacing the fuel pump relay

Step 1: Install the relay. Install the relay into the fuse box in the same way you removed the old relay.

Step 2: Install the fuse box cover. Set it in place.

• Attention: If you had to remove screws or bolts from the cover, be sure to install them. Don't overtighten them or they will break.

Step 3: Remove the fuel tank cap from the fuel tank.. Reinstall the fuel tank cap and make sure it is tight.

This ensures that the fuel system is fully pressurized when the fuel pump is turned on.

Part 3 of 4: Checking the operation of the fuel pump relay

Step 1 Reconnect the ground cable to the negative battery post.. Remove the nine volt fuse from the cigarette lighter.

Step 2: Tighten the battery clamp firmly. Make sure the connection is good.

• AttentionA: If you didn't have a XNUMX-volt power saver, you'll have to reset all of your car's settings, such as the radio, power seats, and power mirrors. If you had a nine volt battery, you will need to clear the engine codes, if any, before starting the car.

Step 3: turn on the ignition. Listen for the fuel pump to turn on.

Switch off the ignition after the fuel pump stops making noise. Turn the key back on and listen for the click of the fuel pump relay. You may need to have an additional person touch the fuel pump relay to hear a buzz or click.

• AttentionA: You will need to turn the ignition key on and off 3-4 times to make sure the fuel rail is filled with fuel before starting the engine.

Step 4: Turn the key to start and run the engine. Keep track of how long the launch will take during the launch period.

• Attention: Most modern cars won't start until oil pressure builds up.

Step 5: Remove wheel chocks from wheels.. Put it aside.

Part 4 of 4: Test drive the car

Step 1: Drive the car around the block. While checking, listen for any unusual noise from the fuel pump or fuel pump relay.

Also, accelerate the engine quickly to make sure the fuel pump is working properly.

Step 2: Watch the dashboard for engine lights..

If the engine light comes on after replacing the fuel pump relay, further diagnostics of the fuel pump assembly may be required, or even a possible electrical problem in the fuel system. If the problem persists, you should seek help from one of AvtoTachki's certified technicians who can inspect the fuel pump relay and diagnose the problem.