1987 Ford Ranger Fuel Pump Wiring Diagram: Your Ultimate Guide to Diagnosis & Repair

Understanding the 1987 Ford Ranger fuel pump wiring diagram is essential for diagnosing and fixing common fuel delivery issues like a sudden loss of power, engine stalling, or a failure to start. This guide provides the crucial wiring details, clear component locations, and step-by-step troubleshooting steps for both single and dual-tank systems found on the 1987 Ford Ranger. Armed with this information and the correct diagram for your specific truck configuration, you can effectively trace circuits, test components, and restore proper fuel pump operation.

(Article continues in-depth below...)

Electrical Fundamentals: What Powers Your Ranger's Fuel Pump
Before diving into specifics, grasp the core electrical requirements:

  • High Amperage Power: Fuel pumps draw significant current. The main power comes directly from the battery via large gauge wires and high-capacity fuses or fusible links, routed through a relay. This powers the pump motor.
  • Ground: A solid chassis or body ground provides the return path for the current. Corrosion or loose ground points are frequent failure locations.
  • Control Signal: A smaller gauge wire from the PCM (or EEC-IV module on these older trucks) or an oil pressure switch (less common in 1987) tells the fuel pump relay when to activate. This signal is generated when the ignition key is turned to "Run" or "Start," and often requires a signal from the distributor or crankshaft sensor indicating the engine is rotating (Engine Running signal).

Crucial Components in the 1987 Ranger Fuel Pump Circuit

  1. Fuel Pump (In-Tank): The electric motor itself, submerged in the fuel tank. Single-tank Rangers have one pump. Dual-tank systems have two pumps - one in each tank - plus a tank selector valve.
  2. Fuel Pump Relay: The switch that controls high-amperage power flow to the pump(s). It's typically located under the hood in the Power Distribution Center (PDC) near the battery or on the driver's side fender apron.
  3. Inertia Safety Switch: A safety device designed to cut power to the fuel pump in the event of a collision or significant impact. It is usually located inside the passenger cabin, often under the dash on the passenger side near the kick panel or behind the glove box. This is a frequent cause of "sudden" no-fuel problems.
  4. EEC-IV Power Relay (or PCM Relay): Powers the engine computer (EEC-IV module). The computer must have power before it can activate the fuel pump relay.
  5. Fusible Links: Heavy-duty wires designed to melt and break the circuit if overloaded, protecting the wiring harness. They are often connected near the starter solenoid or battery positive terminal and can corrode or break. Regular fuses may also be present in the circuit.
  6. Oil Pressure Switch (Dual-Function Systems - Less Common in 1987): While primarily a sender, some older circuits use it as a backup signal to power the pump if the relay circuit fails. The 1987 Ranger primarily relies on the EEC-IV controlled relay circuit.
  7. Tank Selector Valve (Dual-Tank Models Only): An electrically operated valve that switches the fuel feed line between the front and rear tanks. A separate selector switch on the dashboard controls it.
  8. Tank Selector Switch (Dual-Tank Models Only): The dashboard switch the driver uses to select which tank the fuel is drawn from. This switch controls both the selector valve and which fuel pump is activated.
  9. Engine Computer (EEC-IV Module): The main control unit. It receives inputs (like Ignition Run/Start and Engine Rotation) and sends the ground signal to activate the fuel pump relay.
  10. Wiring Harness: Connects all the components throughout the vehicle. Damage, corrosion, pinched wires, or broken connectors cause many intermittent problems.

Locating Key Components on Your 1987 Ranger

  • Fuel Pump Relay & EEC-IV Relay: Underhood Power Distribution Center (PDC). Identify using the legend on the PDC lid or in your owner's manual. If not there, check the driver's side fender apron. Relays are usually identical - swap them to test (if the EEC relay fails, the pump won't run either).
  • Inertia Switch: Passenger compartment, typically mounted vertically under the dash on the passenger side, often near the center console hump or behind/above the kick panel. Look for a rectangular box with a red reset button on top.
  • Fusible Links: Attached to the large positive cable running from the battery to the starter solenoid. They are shorter wires covered in thicker insulation, connected via eyelet terminals. Check them visually and by tugging gently to ensure integrity. Also check the fuse panel (cabin and engine bay).
  • EEC-IV Module: Generally located behind the passenger side kick panel or under the dash on the passenger side.

Detailed Wiring Breakdown (Generalized - ALWAYS Verify Colors)
WARNING: Wiring colors can vary slightly depending on trim level, factory options, and whether it's a dual or single tank truck. USE THIS AS A GUIDE, BUT VERIFY WITH YOUR OWN EYES. Colors fade, repairs happen. Trace the wire physically where possible.

  • High Current Power Path:

    • Battery (+) Terminal --> Large Fusible Link(s) (often near starter solenoid) --> High-Amperage Feed to Power Distribution Center (PDC).
    • PDC --> High-Capacity Fuse (e.g., 20A) --> Fuel Pump Relay (Terminal #30 - Common Input).
    • Fuel Pump Relay Output (Terminal #87) --> To Inertia Switch Input.
    • Inertia Switch Output --> To Fuel Pump(s). On Dual Tank Models, this wire often runs to the Tank Selector Switch first, which then directs power to either the Front or Rear Pump.

  • Fuel Pump Relay Control Circuit:

    • Relay Terminal #86: Receives ignition-switched (+) power. This usually comes from the Ignition Switch in "Run" or "Start" position. (Switched Ignition Feed).
    • Relay Terminal #85: Receives the Ground Signal from the EEC-IV Module. This is how the computer turns the pump on. When the EEC provides this ground path, the relay clicks ON.
    • Relay Terminal #30: High Current Input (as above).
    • Relay Terminal #87: High Current Output (to inertia switch/fuel pumps).
    • Relay Terminal #87a: Usually not used in this circuit.

  • EEC-IV Power & Inputs:

    • Battery Power (via Fusible Links/EEC Relay) --> EEC-IV Module (Power Input Pin - e.g., Pin 37 on many).
    • Key Power (Switched Ignition) --> EEC-IV Module (Ignition Input Pin - e.g., Pin 1).
    • EEC-IV Module (Ground Output for FP Relay - e.g., Pin 22) --> Fuel Pump Relay (Terminal #85).
    • PIP Signal (Profile Ignition Pickup) from Distributor / Crankshaft Sensor --> EEC-IV Module. This is the critical "Engine Rotation" signal required for the EEC to continue grounding the FP relay once the engine starts. If lost while running, the engine stalls.

  • Fuel Pumps & Selector System (Dual Tank Models):

    • Power Feed from Inertia Switch --> Tank Selector Switch Input.
    • Tank Selector Switch has two outputs:
      • One to Front Tank Fuel Pump (and Front Tank Sender).
      • One to Rear Tank Fuel Pump (and Rear Tank Sender).
    • Tank Selector Switch also sends a signal to the Tank Selector Valve (often a 2-wire or 3-wire plug) to switch the fuel flow between tanks.

Troubleshooting: Step-by-Step Procedures

1. Initial Checks & Safety:
* Listen: Turn the key to "Run" (not Start). Do you hear the fuel pump hum for 1-2 seconds? If YES in one tank but not the other (dual tank), suspect selector switch, wiring to that pump, or the pump itself. If NO in both tanks, proceed.
* Check Fuel Level: Obvious but critical. The pump needs fuel to cool/lubricate.
* Check Fuses & Fusible Links: Visually and with a multimeter for continuity. Check main power feed fuses/links near the battery/starter and related fuses in the underhood PDC and cabin fuse panel.
* Battery Disconnect: Disconnect the negative battery terminal before working under the vehicle near the fuel tanks or lines. Fuel vapor ignition is a severe risk.
* Reset Inertia Switch: Locate the inertia switch. Firmly press the red reset button on top. Try starting.

2. Is The Fuel Pump Relay Clicking?
* Find the Fuel Pump Relay (PDC).
* Turn the key to "Run." You should hear/feel the relay click ON for 1-2 seconds, then click OFF. No Click?
* Swap Relays: Temporarily swap the Fuel Pump Relay with an identical one (like the EEC Relay). Try again. If it clicks now, replace the faulty relay.
* Relay Still Not Clicking After Swap? Check Power Input to Relay:
* Use a multimeter. Set to DC Volts. Ground the black lead.
* Key OFF: Probe Relay Socket Terminal #30. Should have battery voltage (~12V) constantly.
* Key ON (Run): Probe Relay Socket Terminal #86. Should have battery voltage (~12V) only in Run/Start.
* If Terminal #30 Missing Voltage: Problem with the high-amperage feed from battery (fusible links, corrosion).
* If Terminal #86 Missing Voltage in RUN: Problem with the ignition-switched power circuit (ignition switch, wiring).
* If both #30 & #86 Have Power: Probe Relay Socket Terminal #85. Key ON. Should show a ground signal (near 0V) momentarily. If NO Ground Signal:
* Check the ground wire from #85 socket to the EEC-IV Module Pin. Disconnect, check continuity to ground? It should only show ground when commanded by the EEC. Check the EEC ground pins and power feeds (Pins 37, 1, 57 common grounds).
* Suspect EEC-IV Module, PIP signal loss (distributor/stator failure), or wiring fault between EEC and relay socket.

3. Relay Clicks, But Pump Doesn't Run:
* Verify Inertia Switch: Check for power IN to the inertia switch with key ON (should be same as pump activation time). Then check for power OUT of the inertia switch. If power IN but not OUT, the switch is faulty or not reset. Test continuity across it.
* Check for Voltage at Pump Connector:
* Access the fuel pump electrical connector near the top of the fuel tank (safely! Disconnected battery first!). For dual tanks, you'll need to check the connector for the pump in the selected tank.
* Identify the pump power wire. Disconnect the plug. Set multimeter to DC Volts.
* Ground the black lead on the vehicle chassis. Touch the red lead to the Pump Power Pin in the vehicle-side harness connector.
* Turn Key to RUN for 1-2 seconds. Should see battery voltage (~12V).
* If YES: Problem is the fuel pump itself or its ground connection at the pump/tank. Check the pump ground wire at the tank connector for continuity to chassis ground.
* If NO: Problem is before the pump connector.
* Trace the power wire back: Check connections at the tank selector switch (dual tank), the inertia switch input/output, and the wire from the relay output to the inertia switch. Look for breaks, corrosion, damage.
* Dual Tank Specific: Power comes from inertia switch to the tank selector switch. If power arrives at the selector switch input, but not at its output for the selected tank, the selector switch itself is faulty.

4. Intermittent Failure Issues:
* Common culprits are failing relays, loose/corroded connections (especially ground points like the tank grounding strap), partially damaged fusible links, internal breaks in wiring harnesses (often near connectors or where they flex/bend), and worn fuel pumps.
* The inertia switch can also become sensitive or faulty over time.
* Use the wiring diagram to identify all connection points and harness routing. Wiggle test harnesses and connectors while the engine is idling or with the key in RUN while listening for the pump to engage/disengage.

Key Wiring Colors Reference (Use Caution - Verify!)

  • Constant Power to Relay (Terminal #30): Typically Orange/Light Blue (O/LB) or Heavy Gauge Red/Blue (R/LB).
  • Ignition Switched Power to Relay (Terminal #86): Often Red/Green (R/G) or Green/Yellow (G/Y).
  • EEC Ground Signal to Relay (Terminal #85): Frequently Tan/Yellow (T/Y) or Grey/Red (GY/R).
  • High Current Output from Relay (Terminal #87): Usually Pink/Black (PK/BK) or Pink (P).
  • To Inertia Switch (Input & Often Output): Often Pink/Black (PK/BK) or Pink (P) - same as Relay Output #87.
  • To Fuel Pumps: Vehicle side harness after switch/valve: Often Pink/Black (PK/BK), Pink (P), or Pink/Blue (P/LB).
  • Fuel Pump Ground Wire: Typically Black (BK) or Black/Light Green (BK/LG) - Connected to chassis near tank.
  • Dual Tank Selector Switch Feed (from Inertia): Pink/Black (PK/BK) likely.
  • Dual Tank Switch Output (Front Pump): Pink/Blue (P/LB) likely.
  • Dual Tank Switch Output (Rear Pump): Pink/Red (P/R) or similar.
  • Dual Tank Valve Control: Can vary significantly (Tan/White, Brown/Yellow, White/Black are common combinations).

Conclusion: Master Your Ranger's Fuel System
Diagnosing a fuel pump issue on a 1987 Ford Ranger requires systematically tracing power, ground, and control signals using the specific wiring diagram relevant to your truck's fuel tank configuration. The wiring diagram provided here gives a solid foundation and highlights critical components like the fuel pump relay, inertia safety switch, and the complexities introduced by the dual-tank system. Always prioritize safety by disconnecting the battery before physical work near fuel components. Remember, a lack of power at the fuel pump is far more common than a completely failed pump itself. By methodically testing each point in the circuit – confirming power from the battery through fuses/links, verifying relay operation and control signals from the EEC-IV computer, ensuring the inertia switch is functional and reset, and finally checking power at the pump connector – you can isolate the fault efficiently. Whether it’s a blown fusible link, a stuck relay, a triggered inertia switch, a failing selector switch, corroded wiring, or the pump itself, the wiring diagram empowers you to find the solution and get your 1987 Ranger running reliably again. Keep this guide and your specific diagram handy for reference on future troubleshooting tasks.

Back to blog