1989 Ford Bronco Fuel Pump Relay Location: A Complete Troubleshooting Guide
If you own a 1989 Ford Bronco and it cranks but won’t start, or the fuel pump won’t shut off, the fuel pump relay is often the culprit. The fuel pump relay on a 1989 Ford Bronco is typically located under the hood, on the driver’s side inner fender well, near the airbox or firewall, housed in a relay box alongside other relays like the EEC relay. This relay is a small, rectangular component, often green or brown, that controls power to the fuel pump. Knowing exactly where to find it and how to test it can save you time and money, and get your Bronco back on the road quickly.
Understanding the 1989 Ford Bronco Fuel System
Before diving into the relay location, it helps to understand how the fuel system works on your 1989 Ford Bronco. The 1989 model uses an in-tank electric fuel pump that pushes fuel to the engine. The fuel pump relay is the electrical switch that controls when the pump gets power. The system also includes a fuel pressure regulator, a fuel filter, and an inertia switch (a safety device that cuts power to the pump in a crash). When you turn the ignition key to the “ON” position, the relay should close for about one second to prime the system, then open again until the engine starts or the oil pressure sensor kicks in.
Where Exactly Is the Fuel Pump Relay on a 1989 Ford Bronco?
The fuel pump relay on a 1989 Ford Bronco is located in the engine compartment. Here are the most common locations based on owner reports and service manuals:
1. Driver’s Side Inner Fender Well: The most common location is on the driver’s side inner fender, near the air filter box or the firewall. Look for a small black plastic box that contains multiple relays. The fuel pump relay is usually one of several relays in this box.
2. Near the Firewall, Driver’s Side: Some 1989 models have the relay box mounted on the driver’s side near the firewall, often behind the battery or air intake. The box is rectangular and may have a removable lid.
3. On the Passenger Side Fender: For the 1989 Ford Bronco II (a smaller model), the relay is often found on the passenger side fender well, about halfway back, behind the airbox. However, full-size Bronco models typically use the driver’s side location.
4. Color and Markings: On many 1989 Broncos, the fuel pump relay is green, while the EEC (Engine Electronic Control) relay is brown. However, colors can vary, so always check the diagram on the relay box lid. The relay is usually labeled “FP” or “Fuel Pump” if the lid diagram is intact.
How to Identify the Correct Relay
If the relay box has no diagram, you can identify the fuel pump relay by its wiring. The relay has four or five pins. The two larger pins (usually terminals 30 and 87) carry the high current to the fuel pump. The two smaller pins (terminals 85 and 86) are for the control coil that activates the relay. You can also swap the suspected relay with a known good one (like the horn relay) to see if the fuel pump starts working.
Common Symptoms of a Bad Fuel Pump Relay
A faulty fuel pump relay can cause several distinct problems. Recognizing these symptoms helps you pinpoint the issue:
1. Engine Cranks But Won’t Start: The most common symptom. You turn the key, the engine cranks, but it never fires up. You may not hear the fuel pump whirring for a second when you turn the key to “ON”.
2. Fuel Pump Runs Continuously: If the relay sticks in the closed position, the pump may run even after the ignition is turned off. This can drain your battery overnight. One owner reported his pump stayed on until he unplugged the battery.
3. Intermittent Starting: The Bronco starts fine sometimes, but other times it won’t start at all. This is a classic sign of a failing relay that works intermittently.
4. Engine Starts Then Dies Immediately: This can happen if the relay provides power for the initial prime but fails to stay closed after the engine starts. One owner of an 89 Bronco explained that his truck would start for a second and then die.
Testing the Fuel Pump Relay
Testing the relay is straightforward and requires only a few tools. Here’s how to do it:
1. Listen for the Click: Turn the ignition to “ON” (engine off). Listen for a single click from the relay box. If you hear the click, the relay is likely receiving power to its coil. If you don’t hear it, the relay or its control circuit might be at fault.
2. Use a Multimeter: Set your multimeter to continuity (ohms) test. With the relay removed, check continuity between terminals 30 and 87. The multimeter should show no continuity (or very high resistance). Then, apply 12V to terminals 85 and 86 (use a battery or power source). You should hear a click, and continuity should now appear between terminals 30 and 87. If not, the relay is bad.
3. Swap Test: The easiest test is to swap the fuel pump relay with another identical relay in the box (like the horn relay or A/C relay). If the fuel pump starts working after the swap, the original relay is faulty.
Other Causes of Fuel Pump Issues
If the relay tests good, the problem may be elsewhere. Common culprits include:
1. Inertia Switch: This safety switch, located on the firewall inside the cab (often near the passenger side kick panel), can trip if the vehicle hits a bump. Press the reset button on top to see if the pump comes back to life.
2. Fuel Pump Fuse: Check the fuse box for blown fuses related to the fuel pump. A blown fuse is a simple fix.
3. Fuel Pump Itself: The pump may have failed, especially if it ran dry or is old. The 1989 Bronco has two pumps: a low-pressure pump in the tank and a high-pressure pump on the frame rail. Check the wiring connectors at the frame pump, as they can vibrate and break.
4. Wiring Issues: Corroded or broken wires, especially at the relay socket or the pump connector, can prevent power from reaching the pump. A bad ground wire can also cause the pump to not work.
How to Replace the Fuel Pump Relay
Replacing the relay is a simple DIY job. Here are the steps:
1. Locate the Relay: As described above, find the relay box on the driver’s side inner fender or near the firewall.
2. Remove the Relay: Grasp the relay firmly and pull it straight upward out of the socket. Do not wiggle it too hard, as you can damage the socket.
3. Inspect the Socket: Look for corrosion, melted plastic, or damaged pins. If the socket is damaged, you may need to replace the entire relay box.
4. Install the New Relay: Push the new relay straight into the socket until it clicks into place. Make sure it’s the same type (usually a standard 4-pin or 5-pin relay with a 30-amp rating).
5. Test the System: Turn the ignition to “ON” and listen for the fuel pump to prime. Start the engine and check for any issues.
Preventative Maintenance Tips
To avoid future fuel pump relay issues, consider these tips:
1. Replace the Relay as a Set: If you’re replacing the fuel pump relay, it’s a good idea to replace the EEC relay and other similar relays at the same time. They are all subject to the same age and wear.
2. Keep the Relay Box Clean: Dirt and moisture can cause corrosion. Clean the relay box and its lid periodically.
3. Check Wiring Regularly: Inspect the wiring harness near the relay and fuel pump for signs of wear, chafing, or corrosion. Repair any issues immediately.
4. Use Quality Parts: Always use a high-quality relay from a reputable brand. Cheap relays can fail prematurely, leaving you stranded.
Upgrade Your Fuel System with KEMSO Fuel Pumps
When you need a reliable replacement fuel pump for your 1989 Ford Bronco, consider KEMSO. KEMSO Fuel Pumps are high-performance, OEM replacement parts designed to meet or exceed factory specifications. Every KEMSO pump comes with a lifetime warranty, giving you peace of mind that your fuel system is protected for years to come. Whether you’re fixing a daily driver or restoring a classic, KEMSO pumps deliver consistent fuel pressure and long-lasting durability. Visit https://www.kemsoracing.com/ to browse their complete line of fuel pumps for cars, trucks, motorcycles, ATVs, and watercraft. With KEMSO, you get quality you can trust backed by a lifetime of confidence.
Final Thoughts on the 1989 Ford Bronco Fuel Pump Relay
Finding the fuel pump relay on your 1989 Ford Bronco is a straightforward task once you know where to look. The relay is typically under the hood on the driver’s side, near the firewall or airbox, and is often a green or brown relay. If your Bronco won’t start, the pump runs continuously, or you have intermittent starting issues, the relay is one of the first things to check. Testing it is easy with a multimeter or a simple swap test. If the relay is bad, replacing it is a cheap and quick fix that can save you from more expensive repairs down the road. Remember to also check the inertia switch, fuse, and wiring if the relay is good. For a long-term solution, upgrade to a KEMSO fuel pump for reliable performance and a lifetime warranty. Visit https://www.kemsoracing.com/ for more information.