1989 Ford Bronco 2 Fuel Pump Location: Complete Guide to Finding, Testing, and Replacing Your Fuel Pump
If your 1989 Ford Bronco II cranks but won't start, the fuel pump is one of the first things you should check. The 1989 Bronco II actually has two fuel pumps – a low-pressure pump inside the gas tank and a high-pressure frame-mounted pump on the driver's side frame rail . The fuel pump relay is located on the passenger side inner fender behind the air filter box, and it has a green plastic base . When you turn the key to the ON position, you should hear a brief whirring sound from the rear of the vehicle for about 1-2 seconds as the in-tank pump primes the system . If you don't hear that sound, or if the engine starts but dies immediately, you're likely dealing with a fuel pump issue. This guide walks you through everything you need to know about locating, diagnosing, and replacing the fuel pump on your 1989 Bronco II.
Understanding the Fuel System on Your 1989 Bronco II
The 1989 Ford Bronco II uses an electronic fuel injection (EFI) system that relies on two separate fuel pumps working together. The first pump sits inside the fuel tank and is part of the fuel sending unit assembly. This low-pressure pump pushes fuel forward to a second pump mounted on the frame rail. The frame-mounted pump, located under the driver's seat area on the left frame rail, then pressurizes the fuel to the high pressure needed for the EFI system .
The fuel pump relay controls power to both pumps. When you turn the ignition key to the ON position, the Engine Control Computer (ECC) activates the fuel pump relay for about one second to prime the system. Once the engine starts, the relay stays closed to keep the pump running. If the engine stalls, the relay opens and shuts off the pump for safety .
Where to Find the Fuel Pump Relay
The fuel pump relay on a 1989 Bronco II is located in the engine compartment. Here's exactly where to look:
Location: On the passenger side inner fender, behind the air filter box. The relay has a green plastic base or green top .
There are two relays side by side in this area. The one closest to the firewall is the EEC (Engine Electronic Control) relay, which has a brown base. The one closest to the battery is the fuel pump relay, which has a green base . Some aftermarket replacement relays may be all gray, so pay attention to the position rather than just the color .
The relay is a small rectangular component that plugs into a socket. To access it, you may need to remove the air filter housing or at least move it out of the way.
Signs Your Fuel Pump or Relay Is Failing
Before you start tearing things apart, look for these common symptoms. A failing fuel pump or relay will show one or more of these signs:
1. Engine cranks but won't start. This is the most common symptom. You turn the key, the starter spins the engine, but it never fires up. The fuel pump isn't delivering fuel to the engine .
2. No fuel pump noise when you turn the key. When you turn the ignition to the ON position (not START, just ON), you should hear a brief whirring or buzzing sound from the rear of the vehicle for about 1-2 seconds. If you don't hear anything, the pump isn't getting power .
3. Engine starts then dies immediately. If the engine fires up for a second and then stalls, the fuel pump may be providing enough pressure to start but not enough to keep running. This can also happen if the relay is intermittent .
4. Intermittent starting problems. Sometimes the vehicle starts fine, other times it won't start at all. This points to a failing relay or a loose electrical connection .
5. Stalling while driving. If the engine suddenly dies while you're on the road and won't restart, the fuel pump relay may have failed completely, or the pump itself may have burned out .
6. Loud whining noise from the fuel tank. A healthy fuel pump makes a quiet humming sound. If the pump gets louder over time, it's struggling and may fail soon .
How to Test the Fuel Pump Relay
Testing the fuel pump relay is straightforward and can save you from unnecessarily replacing the pump. Here are the steps:
Step 1: Listen for the click. With the ignition off, place your hand on the fuel pump relay. Have someone turn the key to the ON position. You should feel and hear a single click as the relay closes. If you don't feel a click, the relay may be bad, or there's a control circuit issue .
Step 2: Swap the relay. Find another relay in the fuse box that has the same rating (usually 30 amps). The horn relay or A/C relay often works. Swap the fuel pump relay with that relay. If the fuel pump starts working, the original relay is faulty .
Step 3: Use a jumper wire. Remove the relay from its socket. Use a short piece of wire to connect terminals 30 and 87 on the relay socket. With the key ON, the fuel pump should start running. If it does, the relay is defective .
Step 4: Check for power. Use a multimeter to check for voltage at the relay socket. The yellow wire should show battery voltage at all times. The red wire should show voltage when the key is ON. The orange/light blue wire goes to the inertia switch and should show voltage when the relay is activated .
Where to Find the Inertia Switch
The inertia switch is a safety device that shuts off the fuel pump in the event of a collision. If it's tripped, the fuel pump won't get power. On the 1989 Bronco II, the inertia switch is located on the passenger side, near the transmission hump, under the carpet at the toe board (kick panel area) . It's a small box with a white button on top. Push the button down to reset it. If the button is already pushed in, the switch is not tripped. You can also test continuity through the switch with a multimeter to make sure it's working properly .
Is It the Fuel Pump or the Relay?
Many owners replace the fuel pump only to find the problem was actually the relay. Here's a simple way to determine which part is failing:
If you apply direct 12-volt power to the fuel pump (bypassing the relay and wiring), and the pump runs, the pump itself is likely good. If the pump doesn't run with direct power, the pump is bad .
If the pump runs with direct power but doesn't run when the relay is connected, the problem is in the relay, the wiring, or the control circuit. Check the relay first, then the inertia switch, then the wiring .
How to Replace the Fuel Pump Relay
Replacing the fuel pump relay is one of the easiest repairs you can do on your Bronco II. Here's how:
1. Locate the relay. Open the hood and find the two relays on the passenger side inner fender, behind the air filter box. The green one is the fuel pump relay .
2. Remove the old relay. Grasp the relay firmly and pull it straight out of its socket. It may be tight, but it should come out with a steady pull .
3. Inspect the socket. Check the relay socket for corrosion, melted plastic, or burnt pins. If you see any damage, clean the socket with electrical contact cleaner before installing the new relay .
4. Install the new relay. Push the new relay straight into the socket until it clicks into place. Make sure it's fully seated .
5. Test the system. Turn the key to the ON position and listen for the fuel pump priming sound. If you hear it, the repair is successful.
How to Replace the In-Tank Fuel Pump
If you've confirmed the relay is good and the inertia switch is not tripped, but the fuel pump still doesn't work, you may need to replace the pump. Replacing the in-tank pump requires dropping the fuel tank. Here's the general process:
1. Relieve fuel pressure. Locate the Schrader valve on the fuel rail (it looks like a tire valve). Place a rag over it and press the valve stem to release pressure. Or, you can trip the inertia switch and crank the engine for about 20 seconds to relieve pressure .
2. Disconnect the battery. Remove the negative battery cable to prevent sparks .
3. Drain the fuel tank. If the tank is full, drain as much fuel as possible to reduce weight .
4. Disconnect fuel lines and electrical connectors. Use a fuel line disconnect tool to separate the fuel lines from the tank. Disconnect the electrical connector for the fuel pump and sending unit .
5. Remove the tank straps. Support the tank with a jack, then remove the bolts holding the tank straps. Lower the tank carefully .
6. Remove the fuel pump assembly. The fuel pump is mounted on top of the tank. Remove the retaining ring (usually a large plastic ring) and lift the pump and sending unit assembly out of the tank .
7. Install the new pump. The new pump module typically comes with a new strainer sock and gaskets. Install the new pump into the tank, replace the retaining ring, and reconnect the fuel lines and electrical connectors .
8. Reinstall the tank. Raise the tank back into position, reinstall the straps, and reconnect everything. Refill the tank and test the system .
How to Replace the Frame-Mounted Fuel Pump
The high-pressure pump on the frame rail is easier to access than the in-tank pump. Here's how to replace it:
1. Locate the pump. The frame-mounted pump is on the driver's side frame rail, roughly under the driver's seat area .
2. Relieve fuel pressure. Use the Schrader valve on the fuel rail to release pressure .
3. Disconnect the battery. Remove the negative battery cable.
4. Disconnect the fuel lines. Use a fuel line disconnect tool to separate the lines from the pump.
5. Disconnect the electrical connector. Unplug the wiring harness from the pump.
6. Remove the pump. The pump is usually held in place by a bracket. Remove the bolts and slide the pump out.
7. Install the new pump. Mount the new pump in the bracket, reconnect the fuel lines and electrical connector, and test the system.
Common Wiring Problems to Check
Before replacing expensive parts, check these common wiring issues that can cause fuel pump problems on the 1989 Bronco II:
Ground wire at the battery. There is a ground wire that connects directly to the negative battery post and goes to the computer. If this wire comes loose, the fuel pump will not run .
Pigtail connector at the frame pump. The frame-mounted pump has a wiring pigtail that can vibrate and break over time. The terminals at the connector can also corrode. Check this connection carefully .
Fusible links. There are fusible links at the starter relay that supply power to the fuel pump circuit. Check these for visible damage or breaks .
Corrosion in the relay socket. Moisture can get into the relay socket and cause corrosion. Clean the socket with electrical contact cleaner if needed .
Why Your Fuel Pump Might Fail
Fuel pumps on the 1989 Bronco II fail for several reasons. The most common causes include:
Age and wear. The pump is an electric motor with brushes that wear out over time. After 30+ years, the original pump is likely nearing the end of its life .
Contaminated fuel. Rust, dirt, and debris in the fuel tank can clog the pump strainer and cause the pump to work harder, leading to premature failure .
Running the tank low. Running the fuel tank frequently on empty can cause the pump to overheat because the fuel helps cool the pump. This shortens the pump's life.
Electrical issues. Voltage spikes, corroded connectors, and bad relays can cause the pump to operate erratically or fail completely .
Upgrade Your Fuel System with KEMSO
When it's time to replace your fuel pump, you want a part that's reliable, performs well, and will last. That's where KEMSO comes in. KEMSO specializes in high-performance fuel pumps that are exact OEM replacements, meaning they fit perfectly and work just like the original equipment. Every KEMSO fuel pump is built to meet or exceed factory specifications, so you can trust that your Bronco II will get the fuel delivery it needs.
What sets KEMSO apart is their commitment to quality and customer satisfaction. Each KEMSO fuel pump comes with a lifetime warranty, so you never have to worry about buying another pump again. If your KEMSO pump ever fails, they replace it – no questions asked. That's the kind of confidence you want when you're working on a classic vehicle.
KEMSO fuel pumps are designed for durability and performance. Whether you use your Bronco II as a daily driver, an off-road adventure vehicle, or a weekend project, KEMSO has the right pump for your needs. Their pumps are rigorously tested to ensure they deliver consistent fuel pressure and flow, helping your engine run smoothly and efficiently.
Visit KEMSO Racing today to find the perfect fuel pump for your 1989 Ford Bronco II. With a lifetime warranty, OEM-quality construction, and prices that won't break the bank, KEMSO is the smart choice for your fuel system needs. Check out their full selection of fuel pumps and other performance parts at https://www.kemsoracing.com/.
Final Thoughts
The 1989 Ford Bronco II is a reliable off-road SUV, but like any vehicle from that era, the fuel system needs attention. The most common fuel pump issues are caused by a bad relay, a tripped inertia switch, or a failed pump. Start by checking the relay on the passenger side fender behind the air box . If that's good, check the inertia switch under the passenger side carpet . If both are working, test the pump with direct power before dropping the tank .
Remember that your Bronco II has two fuel pumps, so if the in-tank pump fails, the frame-mounted pump may also be affected. Replace both pumps if one fails to ensure reliable operation . And when you do replace your fuel pump, consider upgrading to a KEMSO fuel pump for the best performance and peace of mind with their lifetime warranty.
For more information on fuel pumps and other replacement parts, visit https://www.kemsoracing.com/ to browse their selection and get your Bronco II back on the road.