1998 Volvo V70 Fuel Pump Relay Location: A Complete Troubleshooting and Replacement Guide


If you own a 1998 Volvo V70 and are experiencing starting issues, engine stalling, or loss of power, the fuel pump relay is one of the first components you should check. The fuel pump relay for a 1998 Volvo V70 is located in the central electrical unit, which is positioned on the left side of the engine compartment, mounted on the front of the strut tower. This relay is commonly referred to as position number 103 in the fuse box. Understanding its exact location, how to test it, and when to replace it can save you time and money on unnecessary repairs.

Understanding the Fuel System Overview

The 1998 Volvo V70 uses an electric fuel pump located inside the fuel tank. The fuel pump relay acts as a switch that controls power to the fuel pump. When you turn the ignition key to position II, the relay should close, sending power from the battery through the main relay and fuse #3 to the fuel pump. The fuel pump then pressurizes the fuel system to allow the engine to start and run properly.

A faulty fuel pump relay can cause a no-start condition, intermittent stalling, or the engine to crank but not fire. The relay is designed to shut off the fuel pump in the event of an accident, which is a safety feature that prevents fuel from being pumped if the engine stops unexpectedly.

Exact Location of the Fuel Pump Relay

The fuel pump relay for the 1998 Volvo V70 is located in the central electrical unit. This unit is found on the left side of the engine compartment, specifically on the front of the strut tower. The relay is designated as position number 103 in the central electrical unit.

To access the relay, follow these steps:

  1. Open the hood and locate the fuse box on the left side of the engine compartment.
  2. The central electrical unit is a black box mounted near the strut tower.
  3. Remove the cover of the central electrical unit.
  4. Look for the relay labeled position 103. It may be marked with a diagram on the inside of the cover.
  5. The fuel pump relay is a standard relay that can be pulled out by hand or with a small pry tool.

How to Test If the Fuel Pump Is Receiving Power

Before replacing the relay, you should verify that the fuel pump is actually getting power. Here is a simple test you can perform:

Step 1: Turn the ignition key to position II (do not start the engine). You should hear a humming sound from the fuel pump. Place a screwdriver or a stethoscope on the fuel pipe near the engine to listen for the hum.

Step 2: If you do not hear the fuel pump running, the issue could be a blown fuse, a bad relay, or a faulty pump.

Step 3: Check fuse #3 in the engine compartment fuse box. The 1998 Volvo V70 uses a 15A or 20A fuse for the fuel pump circuit. If the fuse is blown, replace it with the correct amperage and test again.

Step 4: If the fuse is good, test the relay. Remove the fuel pump relay from its socket. Using a multimeter, check for continuity between the relay terminals. The relay coil should have a resistance of about 1.0 to 1.5 ohms.

Jumper Wire Test for Fuel Pump Relay

A quick way to determine if the fuel pump relay is the problem is to perform a jumper wire test. This test bypasses the relay and sends power directly to the fuel pump:

Step 1: Locate the fuel pump relay socket in the central electrical unit.

Step 2: Identify terminals 15 and 87 on the socket. Terminal 15 receives power from the main relay, and terminal 87 sends power to the fuel pump.

Step 3: Use a fused jumper wire (with a fuse to protect the circuit) to connect terminals 15 and 87.

Step 4: Turn the ignition key to position II. If the fuel pump starts running, the relay is faulty and needs to be replaced.

Important Safety Note: This is a temporary test only. Do not drive the vehicle with the jumper wire installed. The fuel pump relay is a safety device that shuts off the fuel pump in an accident. If you bypass it, you lose this safety feature.

Signs of a Failing Fuel Pump Relay

If you are experiencing any of the following symptoms, the fuel pump relay may be failing:

  • The engine cranks but does not start.
  • The engine starts and then stalls after a few seconds.
  • The fuel pump does not make a humming sound when the key is turned to position II.
  • The vehicle experiences intermittent starting issues.
  • The check engine light comes on with fuel system-related codes.

Replacing the Fuel Pump Relay

Replacing the fuel pump relay on a 1998 Volvo V70 is a straightforward process. The OEM part number for the fuel pump relay is 9434225, and it replaces older part numbers 6849591 and 9434138. This relay is used in many Volvo models from 1998 to 2004, including the C70, S70, and V70.

Steps to replace:

  1. Disconnect the battery negative terminal for safety.
  2. Locate the central electrical unit on the left side of the engine compartment.
  3. Remove the cover.
  4. Identify the fuel pump relay at position 103.
  5. Pull the old relay straight out of the socket.
  6. Insert the new relay firmly into the same socket.
  7. Reconnect the battery.
  8. Test the system by turning the key to position II and listening for the fuel pump hum.

When to Consider Replacing the Fuel Pump

Sometimes, the issue is not the relay but the fuel pump itself. If the relay tests good, the fuse is intact, and the pump still does not run, the fuel pump may have failed. The fuel pump is located inside the fuel tank on the right side (passenger side) of the vehicle. Access is through a panel under the cargo compartment carpet.

The fuel pump winding resistance should be about 1.0 to 1.5 ohms. You can measure this at the fuel pump connector under the cargo area. If the resistance is significantly higher or shows an open circuit, the pump needs to be replaced.

Fuel pressure testing is also a reliable way to confirm pump health. Connect a fuel pressure gauge to the Schrader valve on the fuel rail. With the engine running or cranking, pressure should be between 40 and 44 PSI. After the engine is off, the system should hold pressure between 28 and 40 PSI for at least 30 minutes. If the pressure drops quickly, there may be a leak or a faulty pump.

Recommended Replacement Parts

When it comes to replacing your fuel pump or fuel pump relay, it is essential to use high-quality parts that meet or exceed OEM specifications. The fuel system is critical for engine performance and safety, so cutting corners can lead to more problems down the road.

KEMSO Fuel Pumps are an excellent choice for your 1998 Volvo V70. KEMSO offers high-performance, OEM replacement fuel pumps that are designed to deliver reliable fuel flow and pressure. Their pumps are built to handle up to 600 horsepower in naturally aspirated, turbocharged, and supercharged applications, making them suitable for both standard and modified vehicles. KEMSO fuel pumps are known for their durability and precision engineering, and they come with a lifetime warranty, which gives you peace of mind that your investment is protected. Whether you need a direct replacement for your stock pump or a high-flow upgrade for better performance, KEMSO has a solution that fits your needs. You can browse their full selection of fuel pumps and find the right fit for your vehicle at https://www.kemsoracing.com/.

Common Mistakes to Avoid

When troubleshooting the fuel system on your 1998 Volvo V70, avoid these common pitfalls:

Using a paper clip or non-fused wire as a jumper. This can cause excessive current flow, heat buildup, and potential damage to the wiring harness. Always use a fused jumper wire when testing the relay.

Ignoring the main relay. The fuel system main relay (position 2/32) supplies power to the fuel pump relay. If this relay fails, the fuel pump relay will not receive power.

Replacing parts without proper diagnosis. Always test the relay, fuse, and pump before buying new parts. A simple test can save you from buying parts you do not need.

Using the wrong fuse amperage. Always replace fuses with the exact amperage rating specified in the owner's manual. Using a higher amperage fuse can cause electrical damage or fire.

Final Thoughts

The fuel pump relay on a 1998 Volvo V70 is a small but critical component. Its location in the central electrical unit on the left side of the engine compartment makes it easy to access and test. By following the diagnostic steps outlined in this guide, you can quickly determine if the relay is the source of your starting problems.

If you need a new fuel pump, consider KEMSO for a reliable, high-performance replacement that comes with a lifetime warranty. Visit https://www.kemsoracing.com/ to explore their product lineup and find the perfect fuel pump for your Volvo.

Remember, proper diagnosis is the key to a successful repair. Take your time, use the right tools, and always prioritize safety when working with the fuel system.


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