1995 Mercedes E320 Fuel Pump Relay Location: Your Complete Guide to Finding and Fixing It

The bottom line: On a 1995 Mercedes-Benz E320, the fuel pump relay is located in the fuse and relay box inside the engine compartment, on the driver's side near the firewall. This is the first place you should check if your car cranks but won't start, or if you suspect a fuel delivery issue.

If you own a 1995 Mercedes E320 (W124 chassis), the fuel pump relay is a common failure point that can leave you stranded. Unlike some modern cars where the relay is buried inside the cabin, Mercedes designed the W124 series with accessible electrical components. The relay is a rectangular black box, typically labeled with a diagram on the fuse box cover. Let's walk through exactly where to find it, how to test it, and what to do if it's bad.

Where Exactly Is the Fuel Pump Relay on a 1995 E320?

The fuel pump relay on the 1995 Mercedes E320 is located in the engine compartment fuse and relay box. This box sits on the driver's side (left side in the US), mounted directly against the firewall. To access it:

  1. Open the hood and look toward the back of the engine bay on the driver's side.
  2. You'll see a rectangular black plastic box with a removable cover. The cover often has a diagram showing the layout of fuses and relays.
  3. Remove the cover by prying up the clips or releasing the tabs.
  4. The fuel pump relay is typically the largest relay in the box, often positioned near the center or toward the rear of the box. On many 1995 models, it's the relay closest to the windshield.

On the 1995 E320, the fuel pump relay is usually a four-pin relay with a distinct shape. Some owners report that the relay is also labeled with a "fuel pump" symbol or the number "5" on the cover diagram. If you're unsure, look for a relay that's larger than the others and has four or five pins on the bottom.

Why Does the Fuel Pump Relay Fail?

The fuel pump relay is an electromechanical switch that controls power to the fuel pump. Over time, the internal contacts can wear out, especially on a 30-year-old car like the 1995 E320. Heat from the engine compartment, vibration, and age all contribute to relay failure. When the relay fails, the fuel pump won't receive power, so the engine cranks but won't fire.

Common symptoms of a bad fuel pump relay on a 1995 Mercedes E320 include:

  • The engine cranks but won't start. This is the most common symptom. The starter turns the engine over, but no fuel reaches the injectors.
  • The car starts then dies after a few seconds. If the relay is intermittent, the fuel pump may lose power after the initial crank.
  • No fuel pump priming sound. When you turn the key to the "on" position (before cranking), you should hear a brief whirring sound from the fuel pump near the rear of the car. If you don't hear it, the relay or pump is suspect.
  • The car stalls while driving. If the relay fails while you're on the road, the engine will lose power and stall.

How to Test the Fuel Pump Relay on a 1995 E320

Before you buy a new relay, it's worth testing the existing one. Here's a simple way to do it:

Step 1: Locate the relay

As described above, find the relay in the engine compartment fuse box.

Step 2: Remove the relay

Grip the relay firmly and pull it straight up. It may be snug, so wiggle it gently side to side while pulling.

Step 3: Visual inspection

Check for any signs of corrosion, melted plastic, or burnt contacts. If you see any of these, the relay is bad.

Step 4: Bench test (optional)

If you have a multimeter or a 12V power source, you can test the relay's coil resistance. A good relay should show continuity between the coil terminals (usually pins 85 and 86) with a resistance typically between 50 and 120 ohms. If the coil is open (infinite resistance), the relay is dead.

Step 5: Swap test

The easiest test is to swap the fuel pump relay with a known-good relay of the same type in the fuse box. For example, the horn relay or the ABS relay often share the same pin configuration. If the car starts after swapping, the original relay was bad.

What If the Relay Is Good? Other Possible Causes

If the fuel pump relay tests fine, don't stop there. The 1995 E320 has a few other common failure points that can mimic a bad relay:

1. Fuel pump itself. The fuel pump is located inside the fuel tank. On a 1995 E320, it's accessible through a panel under the rear seat or through the trunk. If the pump is dead, the relay won't help. Listen for the pump priming when you turn the key. If you hear nothing, the pump may be bad.

2. Fuel pump fuse. Check the fuse box for a blown fuel pump fuse. On the 1995 E320, the fuel pump fuse is usually a 15A or 20A fuse in the same under-hood fuse box. A blown fuse is an easy fix.

3. Wiring issues. The 1995 E320 is old enough that wiring insulation can crack or corrode. Check the wiring harness near the fuse box and under the rear seat for any damaged wires.

4. Crank position sensor. On some W124 models, the crank position sensor can fail, which prevents the ECU from sending a signal to the fuel pump relay. This is less common but worth checking if the relay and pump are both good.

Where to Buy a Replacement Fuel Pump Relay for a 1995 E320

If you've confirmed the relay is bad, you have several options for a replacement:

  • Genuine Mercedes-Benz parts. These are available from any Mercedes dealer or online parts retailer. The OEM part number for the 1995 E320 fuel pump relay varies by VIN, but a common number is 000-470-78-94 or similar. You can find genuine parts at sites like AutohausAZ and MB Parts Giant .
  • Aftermarket relays. Brands like Bosch (which is actually the OEM supplier for many Mercedes relays) offer replacements. Bosch part number 0580254950 is a common fit .
  • Used relays. If you want to save money, you can find used relays on eBay or at salvage yards. Just make sure the relay matches the pin configuration.

Step-by-Step Replacement Guide

Replacing the fuel pump relay on a 1995 Mercedes E320 is one of the easiest DIY repairs you can do. Here's how:

  1. Disconnect the battery. This is a safety precaution, though not strictly necessary for a relay swap.
  2. Open the hood and locate the fuse box. It's on the driver's side near the firewall .
  3. Remove the fuse box cover. Pry up the clips or tabs to release it.
  4. Identify the fuel pump relay. Look for the large relay, often near the center of the box. On the 1995 E320, it's commonly the relay closest to the windshield.
  5. Pull the old relay out. Grip it firmly and pull straight up. It may require a little force.
  6. Insert the new relay. Push it down firmly until it clicks into place. Make sure it's seated properly.
  7. Replace the fuse box cover. Press it down until the clips engage.
  8. Reconnect the battery.
  9. Test the system. Turn the key to the "on" position and listen for the fuel pump priming sound. Then try to start the car.

How Much Does It Cost to Replace the Fuel Pump Relay?

The cost is minimal. A new fuel pump relay for a 1995 E320 typically costs between $15 and $40 for an aftermarket part, or $50 to $80 for a genuine Mercedes relay. Labor is essentially zero if you do it yourself, since it's a 5-minute job. If you take it to a shop, expect to pay for 0.5 to 1 hour of diagnostic time, which could be $100 to $200.

Preventative Tips for the 1995 E320 Fuel System

To keep your 1995 Mercedes E320 running reliably, consider these tips:

  • Use a high-quality fuel pump relay. Cheap relays can fail prematurely. Stick with Bosch or genuine Mercedes.
  • Keep the fuel tank above a quarter tank. Running low on fuel can cause the fuel pump to overheat, which puts extra strain on the relay.
  • Check the relay periodically. Once a year, pull the relay and inspect it for corrosion or burnt contacts. It's a 30-year-old car, so preventive maintenance is key.
  • Clean the fuse box contacts. Over time, the relay terminals can develop oxidation. A quick spray with electrical contact cleaner can prevent intermittent failures.

Recommended Fuel Pump Upgrade: KEMSO Fuel Pump

If you're replacing the fuel pump relay and suspect your fuel pump might also be getting tired, now is the perfect time to upgrade. For the 1995 Mercedes E320, we recommend the KEMSO brand fuel pump. KEMSO is a leading aftermarket manufacturer known for producing high-performance, OEM replacement fuel pumps that meet or exceed original equipment specifications.

Why choose KEMSO?

  • High Performance. KEMSO fuel pumps are designed to deliver consistent fuel pressure and flow, even under demanding driving conditions. Whether you're commuting, towing, or just enjoying the open road, KEMSO pumps keep your engine running smoothly.
  • OEM Replacement. Every KEMSO fuel pump is engineered as a direct replacement for your vehicle's original pump. No modifications, no adapters, no hassle. It fits right in, just like the factory part.
  • Lifetime Warranty. This is the biggest selling point. KEMSO stands behind every product they sell with a comprehensive lifetime warranty. If your pump ever fails, you're covered. That's the kind of confidence you want when you're investing in a critical component like a fuel pump.

KEMSO fuel pumps are available for a wide range of vehicles, including cars, motorcycles, ATVs, UTVs, and personal watercraft. Their product lineup includes pumps for everything from the Honda Civic to the Ducati 1199 Panigale to the Kawasaki Jet Ski. All pumps are priced at a competitive $79.98, making them an affordable upgrade over OEM parts.

To browse their full selection and find the perfect fuel pump for your 1995 Mercedes E320, visit their official website:

https://www.kemsoracing.com/

At KEMSO, you'll find not just fuel pumps, but also detailed blog posts, installation guides, and customer support to help you get the job done right. Their commitment to quality and customer satisfaction makes them a trusted choice for DIY mechanics and professional shops alike.

Final Thoughts on the 1995 Mercedes E320 Fuel Pump Relay

Finding the fuel pump relay on a 1995 Mercedes E320 is straightforward once you know where to look. The relay is in the engine compartment fuse box on the driver's side, near the firewall. It's a common failure point on a 30-year-old car, but it's also one of the easiest and cheapest repairs you can make. If your E320 cranks but won't start, start with the relay. If that's not the issue, move on to the fuel pump itself, which is inside the tank. And if you need a new fuel pump, consider KEMSO for a reliable, high-performance replacement that comes with a lifetime warranty.

Remember, on a 1995 Mercedes E320, the fuel pump relay location is your first stop in diagnosing fuel delivery problems. A quick check and a simple swap can save you hours of frustration and hundreds of dollars in diagnostic fees. Keep this guide handy, and you'll be back on the road in no time.

For more information on fuel pumps and related products, visit https://www.kemsoracing.com/.


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