1988 Ford Bronco Fuel Pump Relay Location: Where to Find It and How to Test It

If you own a 1988 Ford Bronco (full-size or Bronco II) and are dealing with a no-start condition, the fuel pump relay is one of the first components you should check. The fuel pump relay on a 1988 Ford Bronco II is located on the passenger side inner fender, behind the air box, under a black plastic cover. There are two relays side by side – the one closest to the firewall is the EEC (Engine Electronic Control) relay, and the one closest to the battery is the fuel pump relay. The factory relay has a green base, while the EEC relay has a brown base, making them easy to distinguish. For the full-size 1988 Ford Bronco (F-150 based), the fuel pump relay is typically located on the driver’s side inner fender well, near the battery, inside the power distribution box. This guide will walk you through the exact location, how to identify the correct relay, and how to test it to get your Bronco running again.

Why the Fuel Pump Relay Matters

The fuel pump relay is a critical electrical switch that controls power to the fuel pump. When you turn the key to the "ON" position, the vehicle's computer (EEC-IV) grounds the relay for about two seconds, closing the circuit and sending power to the fuel pump to prime the system. Once the engine starts and reaches about 400 RPM, the computer keeps the relay grounded so the pump runs continuously. If the relay fails, the fuel pump won't receive power, and your engine will crank but not start. Common symptoms of a failing relay include:

• Engine cranks but won't start – This is the most common symptom
• No fuel pump hum – You should hear a brief whirring sound from the fuel tank area when you turn the key to "ON"
• Intermittent starting issues – The truck may start sometimes but not others, especially when hot
• Engine starts then dies – The relay may work initially but fail to stay engaged

Step-by-Step: Locating the Fuel Pump Relay on a 1988 Bronco II

Step 1: Open the hood and locate the air filter box on the passenger side of the engine bay. The fuel pump relay is mounted on the passenger side fender, directly behind the air box assembly.

Step 2: Remove the black plastic cover that protects the relay area. You may need to unclip or unscrew the cover. Behind it, you will see two identical-looking relays mounted side by side.

Step 3: Identify the correct relay. The relay closest to the firewall (rear of the vehicle) is the EEC relay (brown base), and the relay closest to the battery (front of the vehicle) is the fuel pump relay (green base). If the relays have been replaced before, they may both be gray or black – in that case, you need to check the wiring or swap them to test.

Step 4: For the full-size 1988 Bronco, the relay is located on the driver's side inner fender, near the battery, inside the power distribution box (often called the "fuse box"). Look for a green or gray relay with 4 or 5 pins.

How to Test the Fuel Pump Relay

Before replacing the relay, you can test it with a simple multimeter or by swapping it with a known-good relay.

Method 1: Listen for the relay click. Have a helper turn the key to the "ON" position (do not crank the engine). Place your hand on the relay – you should feel and hear a distinct click for about 2 seconds. If you hear the click but the fuel pump doesn't run, the relay may have good coil power but bad internal contacts.

Method 2: Check for voltage at the relay. With the key off, pull the relay out of its socket. Using a test light or multimeter, check for 12 volts at the socket terminals. You should have constant power on at least one terminal (the yellow wire) and ignition-switched power on another (the red wire). If there is no power at these terminals, check the fusible links connected to the starter solenoid on the inner fender.

Method 3: Swap the relay. If you have a similar relay in the fuse box (such as the horn relay or EEC relay), swap them temporarily. If the fuel pump starts working after the swap, the original relay is faulty.

Method 4: Use the fuel pump test port. On the 1988 Bronco II, there is a diagnostic test port (often located near the engine) that can be used to ground the fuel pump relay manually. Apply a ground to this test port with the key on – if the fuel pump runs, the relay and wiring are good, and the issue is likely the computer (EEC) not providing the ground signal.

Other Common Fuel System Issues to Check

If the relay is working but the fuel pump still doesn't run, the problem may be elsewhere in the circuit:

Inertia switch – This safety switch, located inside the passenger compartment on the passenger side kick panel or near the transmission hump, cuts power to the fuel pump in the event of an accident. Check if the red button on top is popped up. If it is, press it down to reset the switch. You can also bypass the inertia switch temporarily with a jumper wire to test if it is faulty.

Fusible links – Near the starter solenoid on the driver's side fender, there are fusible links that provide power to the fuel pump relay and the EEC relay. If these links are melted or broken, the relay will not receive power.

Fuel pump wiring – The 1988 Bronco II has two fuel pumps: a low-pressure lift pump inside the fuel tank and a high-pressure pump mounted on the frame rail under the driver's seat. Both pumps receive power from the same wire from the inertia switch, but there is a splice point near the frame rail pump that is known to fail. Check for broken wires or corrosion at this connection.

Ground connections – Ensure the fuel pump assembly has a good ground connection at the frame near the tank. A poor ground can prevent the pump from running even if it has power.

Replacement Part and What to Look For

When replacing the fuel pump relay, you can purchase a standard 4-pin or 5-pin relay from most auto parts stores. The original factory relay is green, but aftermarket replacements are typically gray and work for both the fuel pump and EEC relay positions. The part number for the OEM fuel pump relay is E8TZ-14B292-A for the 1988 Bronco II. If you cannot find the exact relay, any 4-pin or 5-pin relay with the same terminal configuration will work, as the 5-pin relays are backward compatible with the 4-pin sockets (the extra pin is simply not used).

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Summary

If your 1988 Ford Bronco (Bronco II or full-size) cranks but won't start, the fuel pump relay is a top suspect. On the Bronco II, it is located on the passenger side fender behind the air box – the green relay is the fuel pump relay, and the brown relay is the EEC relay. On the full-size Bronco, it is on the driver's side inner fender near the battery. Test the relay by listening for a click, checking for voltage, or swapping it with a similar relay. If the relay is good, check the inertia switch, fusible links, and wiring for power delivery. For a reliable replacement, consider KEMSO fuel pumps with a lifetime warranty. Visit https://www.kemsoracing.com/ for more information.