1999 Volvo S70 Fuel Pump Relay: Location, Symptoms, and Replacement Guide

If you own a 1999 Volvo S70 and your car is having trouble starting, stalling, or hesitating during acceleration, the fuel pump relay is often the first component to check. The fuel pump relay on a 1999 Volvo S70 is located in the central electrical unit (also called the relay box or fuse box) under the hood, on the driver's side near the strut tower. This small, inexpensive relay controls power to the fuel pump, and when it fails, it can mimic a dead fuel pump or a bad ignition system. In this guide, we will walk you through the exact location, common symptoms, how to test the relay, and what to do if you need a replacement.

Where Is the Fuel Pump Relay Located on a 1999 Volvo S70?

The fuel pump relay on a 1999 Volvo S70 is located in the central electrical unit under the hood. This box is situated on the driver's side of the engine bay, mounted near the strut tower. To access it, you need to open the hood and look for a black plastic box with a removable cover. Inside, you will find a series of relays and fuses. The fuel pump relay is typically labeled on the underside of the cover, but if the label is missing, you can identify it by its position: it is the fourth relay from the front in the first row of relays, according to multiple Volvo forums and manuals .

The relay itself is a standard 4-pin or 5-pin relay, often colored black or gray. The part number for the genuine Volvo fuel pump relay is 9434225 . This relay is used across many Volvo models from the late 1990s and early 2000s, including the S70, V70, and C70. If you are unsure, you can always check the owner's manual or look for a diagram on the underside of the relay box cover.

Common Symptoms of a Bad Fuel Pump Relay

A failing fuel pump relay can cause a variety of driveability issues. Here are the most common symptoms reported by Volvo S70 owners:

  1. Engine Cranks But Does Not Start – This is the most obvious symptom. If the relay fails, the fuel pump will not receive power, so no fuel reaches the engine. The engine will crank but never fire up .

  2. Intermittent Stalling – Sometimes the relay works intermittently. The car may start and run fine for a few minutes, then suddenly stall. After waiting a few minutes, it may restart. This is a classic sign of a failing relay .

  3. Hesitation or Loss of Power – When accelerating, especially uphill or under load, the engine may hesitate or feel like it is not getting enough fuel. This can happen if the relay is not fully closing or is making poor contact .

  4. No Fuel Pump Prime Sound – When you turn the ignition key to the "ON" position (before cranking), you should hear a brief whirring sound from the fuel pump under the rear seat. If you do not hear this sound, the relay might be bad .

  5. Check Engine Light – In some cases, a bad relay can trigger a diagnostic trouble code (DTC) related to the fuel system, such as a low fuel pressure code or a generic fuel pump circuit code.

How to Test the Fuel Pump Relay

Before buying a new relay, it is wise to test the existing one. Here is a simple step-by-step process:

Step 1: Locate the relay – Follow the instructions above to find the central electrical unit and the fuel pump relay.

Step 2: Listen for the click – With the relay still installed, ask a helper to turn the ignition key to the "ON" position. You should hear a distinct click from the relay. If you hear the click but the pump still does not run, the relay may be working but the pump itself may be bad. If you do not hear the click, the relay coil may be faulty.

Step 3: Swap the relay – The easiest way to test a relay is to swap it with an identical relay from the same box. For example, the horn relay or the windshield wiper relay are often the same type. If the fuel pump starts working after the swap, the original relay is bad .

Step 4: Use a multimeter – If you have a multimeter, you can test the relay for continuity. Remove the relay and apply 12V to the coil terminals (usually pins 85 and 86). You should hear a click, and the continuity between the switch terminals (pins 30 and 87) should be near zero ohms. If the relay does not click or the continuity is broken, replace it.

How to Replace the Fuel Pump Relay on a 1999 Volvo S70

Replacing the fuel pump relay is a straightforward job that requires no special tools. Here is how to do it:

  1. Disconnect the battery – For safety, disconnect the negative battery terminal before handling any electrical components.

  2. Open the relay box – Lift the clips on the central electrical unit cover and remove it.

  3. Remove the old relay – Grasp the fuel pump relay firmly and pull it straight up. It may require a gentle wiggle to free it from the socket.

  4. Install the new relay – Align the pins with the socket and push the new relay down until it clicks into place. Make sure it is fully seated.

  5. Reconnect the battery – Reattach the negative battery terminal.

  6. Test the system – Turn the ignition to the "ON" position and listen for the fuel pump prime sound. Start the engine to confirm the repair.

Where to Buy a Replacement Fuel Pump Relay

You have several options when purchasing a replacement fuel pump relay for your 1999 Volvo S70:

  • Genuine Volvo Part – The OEM part number is 9434225 . This is the safest choice if you want a direct fit. You can find it at a Volvo dealership or online Volvo parts retailers. The price is usually between $20 and $40.

  • Aftermarket Relays – Many auto parts stores sell universal relays that fit the Volvo S70. Brands like Bosch, Standard Motor Products, and Rostra offer compatible relays. Rostra part number 60-0180 is listed as a fuel pump relay for many Volvo models . These are often cheaper, ranging from $10 to $25.

  • Online Retailers – Websites like IPD USA, Volvo Parts Giant, and Volvo Cars OEM Parts Direct stock genuine and aftermarket relays . You can also find them on eBay or Amazon.

Why Choose a KEMSO Fuel Pump for Your Volvo S70?

While the fuel pump relay is often the culprit, sometimes the fuel pump itself fails. If you are replacing the fuel pump, consider upgrading to a KEMSO fuel pump. KEMSO fuel pumps are designed as high-performance OEM replacements for the Volvo S70 and many other vehicles. They offer several advantages over standard factory pumps:

  • Performance – KEMSO pumps deliver a higher flow rate (340 LPH) compared to stock pumps, which can improve throttle response and support higher horsepower if you have modified your engine .

  • OEM Replacement – They are built to be direct drop-in replacements, meaning no modifications are needed to install them in your Volvo S70 .

  • Lifetime Warranty – Every KEMSO fuel pump comes with a lifetime warranty, giving you peace of mind that your investment is protected .

If you need a new fuel pump for your 1999 Volvo S70, visit KEMSO Racing online at https://www.kemsoracing.com/ to browse their selection of high-quality fuel pumps. They offer pumps for a wide range of applications, including the P80 platform that includes the S70, V70, and C70.

Additional Tips for Volvo S70 Fuel System Maintenance

Maintaining your fuel system is crucial for the longevity of your Volvo S70. Here are a few extra tips:

  • Check the fuel pump fuse – Before replacing the relay, check the fuel pump fuse (usually a 15A or 20A fuse) in the same relay box. A blown fuse can cause the same symptoms as a bad relay.

  • Listen for the pump – If you suspect the fuel pump itself is failing, turn the key to the "ON" position and listen near the rear passenger seat. The pump is located inside the fuel tank. If you hear a loud whining noise, the pump may be wearing out.

  • Keep the tank full – Running the tank low on fuel frequently can cause the fuel pump to overheat, as the fuel acts as a coolant for the pump. This can shorten its lifespan.

  • Replace the fuel filter – A clogged fuel filter can strain the fuel pump and cause similar symptoms. It is recommended to replace the fuel filter every 30,000 miles or as part of your regular maintenance schedule.

Conclusion

The 1999 Volvo S70 fuel pump relay is a small but critical component that can cause major headaches if it fails. Located in the central electrical unit under the hood, it is easy to access and test. If you experience symptoms like no start, stalling, or hesitation, start by checking the relay. Swapping it with a known good relay is a quick diagnostic step. If the relay is bad, replace it with a genuine Volvo part or a quality aftermarket relay.

If you need a new fuel pump for your 1999 Volvo S70, consider upgrading to a KEMSO fuel pump for superior performance, a direct OEM fit, and a lifetime warranty. For more information, visit https://www.kemsoracing.com/ to see their full product line.


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