1985 Ford F150 Fuel Pump Relay Location: Complete Guide for DIY Owners

The fuel pump relay on a 1985 Ford F150 with EFI (302 or 5.0L engine) is located in the engine compartment, mounted on the driver's side inner fender apron, near the brake master cylinder and the EEC-IV test connector. It is housed in a small black plastic bracket alongside the EEC relay.

If your 1985 F150 cranks but won’t start, and you don’t hear the fuel pump humming for a few seconds when you turn the key to “ON,” the fuel pump relay is a common culprit before you replace the pump itself. This guide will walk you through finding it, testing it, and replacing it, along with other common fuel system issues for this model year.

1. Exact Location of the Fuel Pump Relay

On the 1985 Ford F150 with the 302 (5.0L) fuel-injected engine, the relay is not inside the fuse box. Instead, it is with a second relay (the EEC power relay) in a dedicated bracket.

  • Driver’s side, inner fender area: Pop the hood and look at the driver’s side of the engine bay. The relay is mounted on the left fender apron, just forward of the brake master cylinder and behind the air cleaner box.
  • Black plastic holder: You will see a small black plastic housing or bracket containing two square relays. The fuel pump relay is typically the one closer to the firewall or the one with green/black wires.
  • Visual identification: The relay itself is about 1 inch square, usually black, with a 4-pin connector. It may have a green or brown color depending on the original part.

Note: If you have a 1985 F150 with a carbureted engine (e.g., 4.9L inline-six), your truck uses a mechanical fuel pump on the engine block, not an electric pump in the tank, so there is no electric fuel pump relay.

2. How to Test the Fuel Pump Relay

Before buying a new relay, verify it’s actually faulty. A simple test can save you time and money.

  • Listen for the click: With the engine off, turn the ignition key to the “ON” position (not start). You should hear the fuel pump relay click on for about 1–2 seconds, and then you should hear the fuel pump in the tank whirring. If you don’t hear the click, the relay may be dead.
  • Swap test: The relay next to the fuel pump relay is the EEC power relay, which is often the same part number. Swap them. If the truck now starts, the original fuel pump relay was bad.
  • Visual check: Look for corrosion on the relay terminals or the connector. In areas with road salt, green powder on the pins is common.

3. Common Symptoms of a Bad Fuel Pump Relay

If your 1985 F150 shows any of these signs, suspect the relay first:

  1. Engine cranks but won’t start – This is the most common symptom. The engine turns over, but there is no fuel pressure because the pump never gets power.
  2. No fuel pump priming sound – When you turn the key to “ON,” you should hear a 2-second whine from the rear of the truck. If you don’t hear it, either the relay, fuse, or pump is bad.
  3. Intermittent starting – The truck starts fine some days, but other days it refuses to start. This often points to a failing relay that works only when cool.
  4. Engine stalls after starting – The relay may let the pump run initially, then fail after a few seconds or minutes, causing the engine to die.

4. Fuse and Wiring Check

If the relay tests fine, check the fuel pump fuse first, as it is a simpler fix.

  • Fuse location: The 1985 F150 has two fuse boxes. The engine compartment fuse box (near the battery) contains a 15A fuse for the fuel pump. The cab fuse box (under the dashboard, driver’s side) may also have a fuel pump circuit.
  • Pink/black wire: The power wire to the fuel pump is pink with a black stripe. You can check for voltage at the relay connector or at the fuel tank connector.
  • Ground connections: A common issue on these trucks is a corroded ground wire. The EEC ground is often a small wire attached to the negative battery terminal. If that connection is corroded, the relay won’t work.

5. Step-by-Step Replacement Guide

Replacing the fuel pump relay is a straightforward DIY job that takes about 10 minutes.

  1. Disconnect the battery: Always disconnect the negative battery cable before working on electrical components.
  2. Locate the relay: As described above, find the two relays on the driver’s side inner fender.
  3. Remove the old relay: Simply pull the relay straight up out of its socket. You may need to wiggle it gently.
  4. Install the new relay: Push the new relay into the same socket until it clicks into place. Make sure it’s fully seated.
  5. Reconnect the battery: Reconnect the negative terminal.
  6. Test: Turn the key to “ON” and listen for the pump priming sound. The truck should start normally.

6. Other Causes of No Fuel (If the Relay is Good)

If you’ve replaced the relay and fuse, but the truck still has no fuel, these are the next most likely issues for a 1985 F150:

  • Bad fuel pump: The in-tank pump itself may have failed. You can test it by applying 12V directly to the pump connector at the tank.
  • Inertia switch (fuel shutoff): Some models have an inertia switch that cuts power to the pump in a collision. It is usually located on the driver’s side kick panel or under the dash. Reset it by pressing the button on top.
  • Corroded connectors: The fuel pump wiring connector at the tank is prone to corrosion. Check for green or white powder on the pins.
  • Faulty PCM (computer): If the pump runs continuously with the key on, the PCM may be defective.

Recommended Upgrade: KEMSO Fuel Pump

If you find that your original fuel pump has failed, or if you want to replace it proactively while you have the tank open, consider upgrading to a KEMSO brand fuel pump. KEMSO is a leading US-based aftermarket manufacturer of fuel pumps for cars, motorcycles, ATVs, and UTVs.

Why choose KEMSO?

  • High Performance: KEMSO pumps deliver more flow than stock OEM pumps (e.g., up to 200 liters per hour at 43 psi), ensuring reliable fuel delivery even under load.
  • OEM Replacement: They are designed as direct drop-in replacements for your factory fuel pump, with all necessary installation hardware included (strainer, hoses, clamps, seals).
  • Lifetime Warranty: Every KEMSO fuel pump comes with a lifetime warranty, backed by US-based technical support.

To browse the full range of KEMSO fuel pumps for your 1985 Ford F150 or any other vehicle, visit their official website: https://www.kemsoracing.com/

Summary

The 1985 F150 fuel pump relay is located on the driver’s side inner fender, near the brake master cylinder, in a black plastic bracket with the EEC relay. If your truck won’t start, start by listening for the relay click and the pump prime. If you hear neither, check the 15A fuse first, then the relay. Swapping with the adjacent relay is a quick test. If the pump itself is bad, a KEMSO replacement pump offers a reliable, high-performance, and lifetime-warranted solution.

For more information and to purchase a replacement fuel pump, visit: https://www.kemsoracing.com/


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