1997 Mitsubishi Eclipse Fuel Pump Relay Location: Find & Fix It Fast

The fuel pump relay on a 1997 Mitsubishi Eclipse is located inside the under-hood engine compartment fuse/relay box. Look for a small, square relay typically labeled "FUEL PUMP" or identified by its specific position (often in row 1, farthest towards the passenger side or row 2, farthest towards the driver's side - confirm using your fuse box diagram). It's usually green, black, or tan and plugs into sockets just like the fuses nearby.

Finding a non-working fuel pump relay is a top suspect when your 1997 Eclipse cranks but won't start. Knowing exactly where it is saves crucial time and money, whether you're confirming a hunch or replacing a faulty part. Let's break down the specifics to get you back on the road.

Understanding the Fuel Pump Relay's Job

Before digging into its location, it helps to grasp why this small component is so important:

• The Safety Switch: The ECU (Engine Control Unit) uses the relay to switch the high-current circuit needed for the fuel pump safely. A small signal wire from the ECU can't handle the pump's power draw; the relay bridges this gap.
• Controlled Operation: The relay turns the fuel pump on only when needed: briefly when you first turn the ignition to "ON" (to prime the system), and continuously once the engine starts cranking or running. When you turn the ignition off, it cuts power.
• Protection: It acts as a final control point for the fuel pump circuit. Issues stemming from wiring shorts or pump motor failure sometimes damage the relay itself, potentially protecting other circuits upstream.

Precise Location in the 1997 Eclipse Engine Bay

For the 1997 Mitsubishi Eclipse (both RS, GS, and GS-T models share the general location), follow these steps:

1. Open the Hood: Securely prop open your hood. Ensure the vehicle is parked on level ground with the parking brake engaged.
2. Locate the Main Under-Hood Fuse/Relay Box: Look towards the rear (windshield end) of the engine compartment, near the firewall on the passenger side.
3. Identify the Relay Box: You'll see a rectangular, usually black plastic box with a removable lid. This is the main power distribution center for engine-related fuses and relays.
4. Open the Box: Release the latches or clips holding the lid on and carefully lift it off. You'll often find a fuse layout diagram printed on the underside of the lid. Keep this lid handy!
5. Find the Fuel Pump Relay: Using the diagram printed on the lid is the most reliable method. Look for the relay labeled "FUEL PUMP".
   • Common Positions (Confirm with YOUR diagram!):
     • Position A: Farthest relay towards the passenger side in the front row (closest to the radiator) of relay sockets.
     • Position B: Farthest relay towards the driver's side in the second row (middle row) of relay sockets. Mitsubishi used variations, so the lid diagram is essential.
   • Physical Appearance: It's typically a standard ISO "cube" micro-relay (approx 1" x 1" x 1"), often green, tan, or black. It will have metal terminal pins on the bottom that plug into 4 or 5 sockets.

(Include a clear, zoomed-in photo here showing the open under-hood box with the fuel pump relay identified by an arrow and label. A second photo showing the diagram on the lid is very helpful.)

Symptoms Pointing to a Bad Fuel Pump Relay

How do you know if this specific relay is the problem? Watch for these common signs:

1. Engine Cranks But Won't Start: This is the classic symptom. The starter turns the engine over, but there's no fuel pressure, so it never fires. The fuel pump relay is a primary suspect here.
2. Engine Stalls Suddenly While Driving: If the relay fails catastrophically while the engine is running, power to the fuel pump cuts instantly, causing immediate engine shutoff.
3. Intermittent Starting Issues: A relay starting to fail might work sometimes and not others. The car might start fine one day and then refuse to start the next morning. Sometimes tapping on the relay box might temporarily make it work.
4. No Fuel Pump Prime Sound: When you turn the ignition key to the "ON" position (without cranking), you should hear a brief (1-2 second) humming or buzzing sound from the rear of the car (where the fuel pump is). If you hear nothing consistently, it could point to the relay, fuse, wiring, or pump.

Testing the 1997 Eclipse Fuel Pump Relay (Reliable Methods)

Before spending money on a new relay, it's smart to test:

• The Swap Test (Easiest & Often Reliable):
  1. Locate the Fuel Pump relay as described.
  2. Find another relay in the box that is identical in shape and pin count (size doesn't always match function). Common candidates are the horn relay or the radiator fan relay.
  3. Swap the Fuel Pump relay with the identical horn/fan relay.
  4. Test Function: Turn the ignition to "ON" and listen for the fuel pump prime sound. Try starting the car.
  5. Test the Other Component: Try operating the horn or see if the radiator fan comes on when the engine is warmed up (or A/C is on). If the car starts after swapping relays, but the horn/fan stops working, your original fuel pump relay is likely bad. If the pump still doesn't work and the horn/fan works in the new position, the issue might be elsewhere (fuse, wiring, pump).
• Using a Multimeter (More Technical): Requires some electrical know-how and a digital multimeter.
  1. Check for Power at the Relay Socket (Ignition ON): Set multimeter to DC Volts (20V range). Ground the black probe. Probe the socket terminal corresponding to constant battery power (usually Terminal 30, often fed directly by the Battery fuse). Should read ~12V.
  2. Check for ECU Signal (While Cranking): Probe the socket terminal that receives the ECU signal (usually Terminal 85 or 86). You need a helper to crank the engine. You should see voltage here (close to battery voltage) only while the key is held in the start position or while the engine is running. This verifies the ECU is sending the signal.
  3. Check the Relay Itself: You can test the relay out of the socket:
     • Check Coil Resistance: Use the Ohms setting. Touch probes to terminals 85 and 86. Expect a resistance reading usually between 50-150 ohms. Infinite resistance means open coil (bad). Zero resistance means shorted coil (bad).
     • Check Switch Continuity: Apply 12V (like from a small battery) to Terminals 85 (+) and 86 (-). You should hear/feel a click. Use Ohms setting to check continuity (near 0 ohms) between Terminals 30 and 87. No continuity when voltage is removed. Verify with your specific relay pinout.

Replacing the Faulty Relay

If testing confirms the relay is dead:

1. Purchase the Correct Relay: Obtain a replacement Mitsubishi relay. The Mitsubishi part number is typically MD614677 (supersedes earlier numbers). Standard auto parts stores will carry the correct equivalent (e.g., Bosch 0332019150, Tyco V23134-A52-X003, etc.). Bring the old one to match. Cost is usually around $15-$30.
2. Disconnect Battery (Safety First!): Locate the negative (-) battery terminal in the engine bay. Loosen the clamp nut and carefully remove the negative cable, placing it away from the battery terminal. This prevents sparks or shorts. Wait a few minutes.
3. Locate and Remove the Old Relay: Access the under-hood fuse/relay box as before. Firmly grasp the old fuel pump relay and pull it straight out of its socket. No need to twist.
4. Install the New Relay: Carefully align the pins on the new relay with the sockets. It should only fit one way. Press down firmly and evenly until it clicks or seats fully.
5. Reconnect Battery: Securely reattach the negative battery cable and tighten the clamp nut.
6. Verify Repair: Turn the ignition to "ON" and listen for the fuel pump prime sound (1-2 seconds). Now try starting the engine.

Critical Safety Precautions

• Disconnect Battery: As mentioned, ALWAYS disconnect the negative battery terminal before touching relays or fuses to prevent short circuits or electrical shock. Fuel pump circuits carry significant current.
• No Smoking/Open Flames: You are working near the fuel system. Never work with any source of ignition nearby.
• Release Fuel Pressure (Optional but Wise): While the fuel pump relay won't affect pressure after the key is off, if you suspect other fuel system work might follow or want extra caution, you can relieve fuel system pressure using the Schrader valve on the fuel rail (looks like a tire valve) under the hood. Cover it with a rag before depressing the pin to catch any sprayed fuel.
• Handle Relays Carefully: Pull relays straight out. Don't pry or force them. Avoid bending pins on the new relay when installing.

When the Relay Isn't the Problem

If you've replaced the relay (and confirmed the fuse is good - see below) and the pump still doesn't prime or the engine won't start, the problem lies elsewhere in the fuel or ignition system:

1. Check the Fuel Pump Fuse: The relay provides power to the pump, but that power goes through a fuse first. Locate the fuse box diagram. Find the fuse labeled "FUEL PUMP" or "FP". It's usually 15A or 20A. Pull it out and inspect the wire inside – is it broken/melted? Replace fuses with the exact same amperage rating. Key suspects are the ECU fuse and Ignition fuse as well.
2. Fuel Pump Itself: A failed pump won't run, even with power. Testing involves checking for voltage directly at the pump connector (located under the car near the fuel tank) while cranking, or listening carefully for pump activation (sometimes hard to hear). Requires some wiring knowledge and access.
3. Ignition Switch Issues: A faulty ignition switch might not send the "Start" or "Run" signal properly to the ECU, preventing it from activating the relay.
4. ECU Problems: While less common, a malfunctioning ECU might not send the ground signal needed to energize the relay coil.
5. Wiring Harness Damage: Look for damaged, corroded, or chewed wires anywhere along the circuit – from battery to fuse box, fuse box to relay, relay to pump, and all ECU connections. Check grounds too.
6. Inertia Safety Switch: The 2G Eclipse usually had a fuel cut-off (inertia) switch mounted near the passenger's footwell (kick panel area). After a significant jolt (even just hitting a pothole hard), this switch trips, cutting power to the fuel pump as a safety measure. Check its status (there's usually a reset button on top) – press it firmly. If the button was popped out, resetting it might solve the problem. This is often overlooked.

Why Knowing the Location Empowers You

Locating the fuel pump relay on your 1997 Mitsubishi Eclipse is more than just finding a component; it gives you control over a critical starting system.

• Saves Money: Diagnosing and replacing a relay yourself costs only the part price ($15-$30). A trip to the mechanic for diagnosis and replacement could easily cost $100+.
• Saves Time: Instead of being stranded waiting for a tow or appointment, a quick swap with a known good relay (like the horn relay) can confirm the issue immediately.
• Builds Confidence: Successfully fixing this problem yourself provides valuable experience for tackling future issues on your Eclipse.
• Faster Diagnostics: Being able to quickly rule in or rule out the relay allows you to focus on other potential causes (like the fuel pump or fuse) efficiently.

Knowing precisely where the 1997 Eclipse fuel pump relay lives – in that under-hood fuse/relay box on the passenger side near the firewall, identified by the lid diagram or its common positions – provides a clear starting point. Combine that knowledge with the ability to perform a simple swap test or understand the failure symptoms, and you have a powerful solution for one of the most common reasons a crank-but-no-start condition strikes this generation Eclipse. While a small part, its failure has a big impact, but now you have the direct path to getting your car running again.