1987 Ford Ranger Fuel Pump Relay: Complete Guide to Location, Diagnosis, and Replacement

If your 1987 Ford Ranger with the 2.9L V6 engine cranks but won't start, the fuel pump relay is often the culprit. This small, inexpensive component controls power delivery to both the in-tank low-pressure pump and the frame-mounted high-pressure pump. The fuel pump relay is located on the passenger side of the engine compartment, mounted on the front side of the shock tower on the inner fender above the fender wall . It is a small black box that resembles a wall cell phone charger with coils on one side that plug into the socket . Before replacing expensive fuel pumps or calling a mechanic, testing and replacing this relay can save you time and money.

Understanding the 1987 Ranger's Dual Relay System

The 1987 Ford Ranger 2.9L uses two separate relays mounted side by side on the passenger side fender wall . These are not interchangeable in function:

  • The Brown Base Relay (EEC Relay): This relay powers the engine control computer (EEC) and all engine systems, including the fuel pump relay itself. Without this relay working, the fuel pump relay cannot receive power to operate .
  • The Green Base Relay (Fuel Pump Relay): This is the actual fuel pump relay. The computer controls this relay by grounding it. When the computer receives the ignition signal, it grounds the green relay, which then sends power to both fuel pumps .

The computer activates the fuel pump relay for only two seconds when you first turn the key to the ON position . The relay stays on full time only after the engine starts and RPMs rise above 400 . This is why you should hear the fuel pump hum briefly when turning the key to the ON position before cranking.

Common Symptoms of a Failing Fuel Pump Relay

When the fuel pump relay fails, you will notice one or more of these symptoms:

  1. Engine cranks but will not start: This is the most common symptom. The starter turns the engine over, but the fuel pumps never receive power .
  2. No fuel pump prime sound: When you turn the key to the ON position, you should hear a brief humming sound from the fuel tank area for 1-2 seconds. If you hear nothing, the relay may not be sending power .
  3. Intermittent starting issues: The truck may start sometimes but not others, or may stall while driving and then refuse to restart.
  4. Relay buzzing or clicking: A failing relay may make a buzzing or whining sound when the key is turned, indicating the internal contacts are failing .

How to Test the Fuel Pump Relay

Testing the relay is straightforward and requires only a few tools. Follow these steps:

Step 1: Check for Power at the Relay Sockets
With the key OFF, use a multimeter to check for 12 volts at one slot in the brown base relay socket. You should also see 12 volts at one slot in the green base relay socket with the key OFF . These are fused power wires, each protected by a 30-amp fuse. If you see lower voltage, wire connections are corroded .

Step 2: Test with the Key ON
Install the brown base relay (EEC relay). With the key in the ON position, check the green base relay socket again. You should now see 12 volts at a second slot. If the voltage is lower than battery voltage, there is corrosion between the brown and green relay circuits .

Step 3: The Swap Test
The easiest test is to swap the green fuel pump relay with a known good relay of the same type. If the truck starts after swapping, the original relay was bad. If you have only one working relay, try it in the brown base socket first to confirm that relay works, then move it to the green base socket .

Step 4: Check the Inertia Switch
The fuel pump circuit includes an inertia fuel shutoff switch, typically located on the passenger side under the heater plenum or in the right kick panel . The pink and black wire runs from this switch to the fuel pumps. If the inertia switch is tripped or has failed, no power reaches the pumps even if the relay is working. Check that the switch is pushed down and properly reset .

When to Check the Fuel Pump Itself

If you have confirmed the relay is good but the truck still won't start, the problem may be the fuel pump. Check these items:

Check the fuel pump fuse:
Locate the fuse for the fuel pump circuit, typically a 30-amp fuse in the power distribution box. If the fuse is blown, replace it and test again. If it blows immediately, you have a short to ground .

Test for power at the pump connector:
If you have power at the pump connector but the pump does not run, the pump itself needs replacement . The 1987 Ranger uses two pumps: a low-pressure pump inside the fuel tank and a high-pressure pump mounted on the frame rail . Both must work for the engine to run.

Use the EEC test connector:
The 1987 Ranger has a red EEC test connector under the hood. One pin in this connector is the fuel pump test pin. Grounding this pin with the key ON should force the fuel pump to run. If the pump runs when grounded, the problem is in the wiring between the relay and the computer, not the pump itself .

How to Replace the Fuel Pump Relay

Replacing the fuel pump relay is a simple job that takes less than 15 minutes. Here is the step-by-step process:

  1. Disconnect the battery: Always disconnect the negative terminal before working on any electrical component to prevent short circuits and accidental shocks .
  2. Locate the relay: Find the green base relay on the passenger side fender wall, mounted on the front side of the shock tower .
  3. Remove the old relay: Grasp it firmly and pull straight up. If it feels stuck, gently rock it side to side while pulling. Do not twist or force it, as this can damage the socket .
  4. Inspect the socket: Check for signs of corrosion, melted plastic, or bent pins before installing the new relay .
  5. Install the new relay: Align the prongs with the socket and press it firmly into place until you hear or feel a click. Make sure it is fully seated .
  6. Reconnect the battery: Reattach the negative terminal and tighten it.
  7. Test the repair: Turn the key to the ON position. You should hear the fuel pump hum for one to two seconds. Then start the engine. It should start normally .

Important: Always buy a relay that matches the original part. The fuel pump relay for a 1987 Ford Ranger is a standard 4-pin ISO mini relay rated at 30 or 40 amps . Look for the part number printed on the old relay. Avoid ultra-cheap no-name brands, as they often fail quickly .

Common Wiring Issues to Check

If replacing the relay does not fix the problem, inspect the wiring:

Check the splice in the Tan/Light Green wire:
The tan/light green wire runs between the fuel pump relay and the computer. A common failure point is the splice in this wire. If the splice is corroded or broken, the computer cannot control the relay. The fix is to run a new wire around the splice or unwrap the wiring harness and repair the splice .

Inspect the wiring harness for damage:
Look for chafed, corroded, or loose connections, especially near the steering column and the fuel tank. Over time, wires can chafe or corrode, interrupting power to the pump .

Clean the relay connections:
If you see corrosion or dirt on the relay pins or socket, clean them using a mixture of baking soda and water (1 tablespoon baking soda to 1 cup water). Dip an old toothbrush into the solution and gently scrub the pins and slots. For stubborn corrosion, use electronic contact cleaner. Let everything dry completely before reinstalling the relay .

Why You Should Choose KEMSO for Your Fuel Pump Replacement

If your diagnostic process leads you to the conclusion that the fuel pump itself needs replacement, choosing a high-quality aftermarket option is essential for long-term reliability. KEMSO is a brand that stands out in the fuel pump market for several important reasons.

KEMSO fuel pumps are engineered as high-performance, OEM replacement units. This means they are built to meet or exceed the exact specifications of the original factory pump that came with your vehicle. You get the same fit, the same performance, and the same reliability, but with some significant advantages over the standard OEM part.

Every KEMSO fuel pump comes with a lifetime warranty. This is a commitment to quality that very few manufacturers offer. It means that once you install a KEMSO pump, you are covered for as long as you own the vehicle. If the pump ever fails due to a manufacturing defect, you get a replacement at no additional cost. This peace of mind is invaluable, especially when dealing with a component that is labor-intensive to replace.

KEMSO focuses on delivering a product that is both durable and affordable. Unlike cheap generic pumps that may fail prematurely, KEMSO pumps are built with high-quality internal components designed to withstand the demands of daily driving. Their pumps are designed to work with standard relay wiring setups, so the installation is straightforward.

Whether you drive a Ford Ranger, a Honda Civic, a Subaru, or any other vehicle, KEMSO has a fuel pump solution for you. Visit their website to explore their full range of fuel pump options and find the exact fit for your vehicle: https://www.kemsoracing.com/

Final Thoughts

The fuel pump relay on a 1987 Ford Ranger is a simple, inexpensive part that can cause major headaches when it fails. Always start your diagnosis with the relay before assuming the fuel pump itself is bad. Check both the brown base (EEC) relay and the green base (fuel pump) relay, as one cannot work without the other. If the relay checks out, move on to the inertia switch, the fuses, and the wiring. Replacing the relay is a DIY job that takes less than fifteen minutes and saves you a trip to the mechanic.

Keep a spare relay in your glove box. Because the relay is small and inexpensive, having a spare on hand can save you from being stranded on the road. And if you do end up needing a new fuel pump, trust a brand that backs its products with a lifetime warranty. KEMSO offers the performance and reliability you need, and their lifetime warranty means you will never have to pay for a replacement fuel pump again.

For more information on fuel pumps and to find the right part for your vehicle, visit https://www.kemsoracing.com/.


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