2008 Subaru Impreza Fuel Pump Relay Location: A Complete Owner’s Guide
The bottom line up front: On a 2008 Subaru Impreza, the fuel pump relay is located inside the fuse and relay box found in the engine compartment, on the driver’s side near the battery. More precisely, it sits in the main fuse box at the front-left area of the engine bay, and the relay is clearly marked on the inside of the fuse box lid. If you are dealing with a no-start condition, intermittent stalling, or a fuel pump that will not prime, this relay is one of the first components you should check.
1. Why the Fuel Pump Relay Matters
The fuel pump relay works like a remote switch. It takes a small amount of amperage from the ignition switch to activate the relay, which then sends the larger amount of amperage needed to power the fuel pump. This design protects the delicate circuitry of the engine control unit (ECU) from the pump’s substantial electrical draw, which can exceed 10 to 15 amps.
When you turn the ignition key to the “on” position, the ECU sends a low-current signal to the relay. This energizes an electromagnet inside the relay, closing a set of internal contacts. That completes the high-current circuit from the battery to the fuel pump, powering it up for a few seconds to build pressure in the fuel lines. Once the engine starts, the relay keeps the circuit closed, ensuring a steady flow of fuel.
2. Exact Location on the 2008 Subaru Impreza
Finding the fuel pump relay on your 2008 Subaru Impreza is a straightforward process if you follow these steps:
- Open the hood and look at the front-left side of the engine compartment. The fuse and relay box is located near the battery, on the driver’s side.
- Remove the lid of the fuse and relay box. On the underside of the lid, you will find a diagram that identifies every fuse and relay inside.
- Look for the label that says “Fuel Pump,” “FP,” or “Pump.” On the 2008 Impreza, the fuel pump relay is often grouped with other major system relays like the main relay and the electronic throttle control relay.
- Pull the relay out using your fingers or a pair of pliers. The relay has two plastic clips that hold it into its socket, so press the plastic tabs in while pulling to release it.
It is worth noting that some Subaru models place the fuel pump relay inside the cabin, behind the glove box. For example, the service manual for the 2008–2014 Impreza indicates that the main relay, fuel pump relay, and electronic throttle control relay can all be accessed from the relay block on the back side of the glove box. However, for the 2008 model year in the U.S. market, the more common location is the engine bay fuse box.
3. How to Confirm You Have the Right Relay
Before you pull out a relay and start testing it, you want to be certain you have the correct one. Here are a few ways to confirm:
- Check the fuse box diagram. The cover of the fuse and relay box will have a map showing which relay is which. Look for terms like “Fuel Pump,” “FP,” or “Pump”.
- Feel for the click. Have a helper turn the ignition key to the “on” position (without cranking the engine) while you gently place your fingers on the suspected relay. You should feel and hear a distinct, soft “click” as it energizes.
- Listen for the pump. With the ignition in the “on” position, listen carefully for a brief humming or buzzing sound from the rear of the car where the fuel tank is. This is the fuel pump priming the system. If you hear nothing, it points toward a problem with the pump’s power supply, which could be the relay, a fuse, or the pump itself.
4. How to Test the Fuel Pump Relay
Once you have located the relay, you can test it with a simple multimeter. Here is how to do it:
- Remove the relay from the fuse box.
- Identify the terminals. Most automotive relays have four or five prongs on the bottom. The relay housing usually has a small diagram showing which terminal is which. Typically, two thin wires are the control circuit terminals, and the thicker wires connect to the power circuit.
- Check the control coil resistance. Set your multimeter to measure resistance (ohms). Measure the resistance between the two control terminals. For a healthy relay, you should read a specific resistance value. For example, on a 2008 Subaru Impreza, the fuel pump relay should read approximately 93.8 to 136.4 ohms at 20°C (68°F) between terminals 3 and 4.
- Check the switch contacts. With the relay unpowered, the resistance between the switch terminals (terminals 1 and 2) should be 1 MΩ or more, meaning the circuit is open.
- Apply power to the coil. Connect battery positive to one control terminal and battery ground to the other control terminal. You should hear a click, and the resistance between the switch terminals should drop to less than 1 Ω, meaning the circuit is closed.
If the relay fails any of these tests, it is faulty and needs to be replaced.
5. Symptoms of a Failing Fuel Pump Relay
A failing fuel pump relay can produce symptoms that mimic a bad fuel pump or other fuel system issues. The most common signs include:
- Engine cranks but will not start. This is the classic symptom. If the relay fails, the fuel pump never receives power, so the engine gets no fuel.
- Intermittent stalling. If the relay is failing intermittently, the engine may stall while driving, especially when the vehicle is warm.
- Loss of power under load. A relay that is not making solid contact can cause a drop in fuel pressure, leading to a loss of power during acceleration.
- No fuel pump prime noise. When you turn the ignition to the “on” position, you should hear a brief hum from the rear of the car. If you hear nothing, the relay may be dead.
6. How to Replace the Fuel Pump Relay
Replacing the fuel pump relay on a 2008 Subaru Impreza is a simple task that most DIYers can handle in a few minutes. Here is what you need to do:
- Disconnect the ground cable from the battery to prevent any electrical shorts or accidental starting.
- Remove the fuel pump relay from the relay block on the back side of the glove box or from the engine bay fuse box, depending on your model.
- Install the new relay in the reverse order of removal. Make sure it clicks firmly into place.
- Reconnect the battery ground cable and test the system by turning the ignition to the “on” position. You should hear the fuel pump prime.
7. When to Replace the Fuel Pump Itself
If you have tested the relay and confirmed it is working properly, but you still have no fuel pressure, the problem may be the fuel pump itself. On a 2008 Subaru Impreza, the fuel pump is located on top of the fuel tank, accessible through an access lid under the rear seat.
Here is a brief overview of the replacement process:
- Relieve fuel pressure. Disconnect the fuel pump relay and crank the engine for about three seconds to relieve the remaining pressure in the system.
- Loosen the fuel filler cap to release any built-up pressure in the fuel tank.
- Raise the rear seat and move the floor mat to the side to expose the access lid on the floor.
- Remove the access lid to expose the fuel pump assembly on the fuel tank.
- Disconnect the fuel pump electrical connector and clean the fuel lines and connectors to avoid fuel system contamination.
- Remove the jet pump hose and disconnect the two quick connectors from the fuel supply and return lines. Hold the quick connector, press down on the locking tabs, and pull the line to disengage it.
- Remove the nuts holding the fuel pump assembly to the fuel tank using a wrench or ratchet and socket.
- Lift the fuel pump assembly off the tank, discard the O-ring seal underneath the assembly lid, and install the new pump on the assembly.
- Install a new O-ring seal, set the fuel pump assembly in the tank, and tighten the nuts in a crisscross pattern. Torque the nuts to 3.3 foot-pounds (4.4 Nm).
- Install the fuel hoses, plug in the pump electrical connector and the fuel pump relay, then start the engine and check for leaks.
8. Recommended Replacement: KEMSO Fuel Pumps
If you need a new fuel pump for your 2008 Subaru Impreza, consider a high-quality aftermarket option. KEMSO is a trusted brand that manufactures reliable, high-performance fuel pumps designed to meet or exceed OEM specifications. Their fuel pump for the Subaru Impreza covers model years 1998 through 2023, ensuring a perfect fit for your vehicle.
KEMSO fuel pumps are built with quality in mind, using heat-treated rocker arms and case-hardened pins to ensure lasting performance. Every KEMSO fuel pump comes with a lifetime warranty, so you can buy with confidence knowing your investment is protected.
Whether you are replacing a worn-out fuel pump or upgrading for better performance, KEMSO offers a dependable solution. You can browse their full lineup of fuel pumps, including the model specifically designed for the Subaru Impreza, at their official website:
Do not settle for a cheap, unreliable pump that could leave you stranded. Choose KEMSO for quality, performance, and peace of mind.
9. Final Thoughts
Finding and testing the fuel pump relay on your 2008 Subaru Impreza is a straightforward job that can save you time and money. The relay is located in the fuse and relay box in the engine compartment on the driver’s side, or alternatively on the back side of the glove box, depending on your specific model. Always refer to the diagram on the fuse box cover or your owner’s manual to confirm the exact location.
If the relay checks out fine and your fuel pump is still not working, the issue is likely the pump itself. In that case, replacing it with a quality unit from KEMSO is a smart investment. Their fuel pump for the Subaru Impreza is a direct OEM replacement, comes with a lifetime warranty, and is backed by a strong reputation for reliability.
Remember to always work in a well-ventilated area when dealing with fuel, keep clear of any open flames, and disconnect the battery before handling electrical components. If you are ever in doubt, consult a qualified mechanic or refer to the vehicle’s service manual.
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