1991 Toyota Camry Fuel Pump Relay: The Complete Guide to Location, Diagnosis, and Replacement
Where Is the Fuel Pump Relay Located on a 1991 Toyota Camry?
The fuel pump relay on a 1991 Toyota Camry is located in the engine compartment fuse box. You will find this black, rectangular fuse and relay box mounted near the driver's side strut tower, close to the firewall. Open the hood and look on the driver's side of the engine bay. The box is usually positioned between the battery and the air filter housing .
Inside the fuse box, the fuel pump relay is often labeled as the "Circuit Opening Relay" or "EFI Main Relay" . The cover of the fuse box has a diagram that identifies each component's position and function. The relay itself is a small, square, black plastic component with multiple prongs on the bottom. It is typically one of several identical-looking relays in the box, so the diagram is essential for correct identification .
For 1991 models with the 2.2L 4-cylinder engine, the relay is specifically part of the fuel pump control circuit. There are two relays involved in this system: the EFI main relay and the circuit opening relay . The circuit opening relay is the one that directly controls power to the fuel pump.
How the Fuel Pump Relay Works
The fuel pump relay acts as a switch that controls power to the fuel pump. When you turn the ignition key to the ON position, the relay receives a signal from the Engine Control Unit (ECU) and closes the circuit, allowing battery power to flow to the fuel pump. This primes the fuel system before you start the engine .
Once the engine is running, the relay keeps the fuel pump powered as long as the engine is cranking or running. If the engine stalls or the ignition is turned off, the relay opens the circuit, stopping the fuel pump. This is a safety feature that prevents the fuel pump from running if the engine is not operating .
The relay itself has four terminals: terminal 30 receives constant battery power, terminal 87 sends power to the fuel pump, terminal 85 is the ground connection, and terminal 86 receives the control signal from the ECU . When the ECU grounds terminal 86, it energizes the relay coil, which connects terminal 30 to terminal 87, sending power to the fuel pump.
Symptoms of a Bad Fuel Pump Relay
A faulty fuel pump relay can cause several symptoms that are easy to recognize. The most common sign is that the engine cranks but will not start. You may also notice that there is no humming sound from the fuel tank when you turn the key to the ON position. The engine may also stall intermittently while driving .
Other symptoms include:
- The engine starts briefly then dies
- The engine turns over but does not fire
- No fuel pressure at the fuel rail
- The fuel pump does not run when the ignition is turned on
These symptoms can also be caused by other issues, such as a bad fuel pump, clogged fuel filter, or electrical problems. However, the relay is one of the easiest components to test first.
How to Test the Fuel Pump Relay
Testing the fuel pump relay is a straightforward process that you can do with basic tools. Here are the steps:
Step 1: Locate the diagnostic connector. Under the hood, near the driver's side strut tower, you will find a small plastic box. This is the diagnostic connector. Inside the box are electrical terminals. Look for the terminals labeled FP (fuel pump) and +B (battery positive) .
Step 2: Jump the terminals. Use a short piece of wire to connect the FP and +B terminals. This bypasses the relay and allows the fuel pump to operate if the ignition key is on. If the fuel pump starts running when you jump these terminals, the relay is likely faulty .
Step 3: Listen for the fuel pump. With the test wire in place, turn the ignition key to the ON position (do not start the engine). You should hear a humming sound from the fuel tank area. This sound indicates the fuel pump is receiving power. If you hear the pump running, the fuel pump itself is working, and the problem is likely the relay or the circuit that controls it.
Step 4: Test the relay directly. Remove the relay from the fuse box. Use a multimeter to check for continuity between the relay terminals. Apply 12V power to terminals 85 and 86 to energize the coil. When the coil is energized, you should hear a click and continuity should be present between terminals 30 and 87. If not, the relay is bad .
Step 5: Swap with a known good relay. If you are unsure about the test results, you can swap the fuel pump relay with an identical relay from another circuit, such as the horn or A/C relay. If the car starts with the swapped relay, the original is faulty .
Common Causes of Fuel Pump Relay Failure
Fuel pump relays can fail for several reasons. Age and wear are the most common causes. The relay's internal contacts can become corroded or worn over time, preventing proper electrical connection. Heat and vibration from the engine compartment can also damage the relay's internal components .
Electrical issues such as voltage spikes or short circuits can also cause relay failure. A faulty ECU or wiring problems in the fuel pump circuit can put additional stress on the relay. Moisture or corrosion in the fuse box can also affect the relay's operation.
Step-by-Step Replacement Guide
Replacing the fuel pump relay on a 1991 Toyota Camry is a simple job that takes about 15 minutes. Here is what you need to do:
Step 1: Safety first. Make sure the vehicle is off and the key is removed from the ignition. Disconnect the negative battery cable to prevent any electrical accidents.
Step 2: Locate the fuse box. Open the hood and find the fuse box on the driver's side, near the strut tower and firewall.
Step 3: Remove the fuse box cover. Press the tabs on the sides of the cover and lift it off. Look at the diagram on the underside of the cover to identify the fuel pump relay position.
Step 4: Remove the old relay. Grasp the fuel pump relay firmly and pull it straight out of its socket. You may need to use a relay puller tool or a pair of pliers, but be careful not to damage the socket.
Step 5: Inspect the relay and socket. Check the relay's prongs for any signs of corrosion or damage. Also inspect the socket for any debris or corrosion. Clean the socket if necessary.
Step 6: Install the new relay. Press the new relay firmly into the correct socket. Make sure it is fully seated.
Step 7: Reinstall the fuse box cover. Put the cover back on and press down until it clicks into place.
Step 8: Reconnect the battery. Reconnect the negative battery cable and tighten the terminal.
Step 9: Test the system. Turn the ignition key to the ON position and listen for the fuel pump to prime. Start the engine and verify that it runs properly.
Other Components to Check
If replacing the fuel pump relay does not solve the problem, there are several other components you should check:
The EFI main relay. This relay is also located in the engine compartment fuse box. It provides power to the entire fuel injection system, including the ECU and fuel pump circuit. If this relay fails, the fuel pump will not receive power .
The fuel pump fuse. Check the 30 amp AM2 fuse in the main fuse box. This fuse protects the fuel pump circuit. If the fuse is blown, the fuel pump will not work .
The fuel pump itself. The fuel pump is located in the fuel tank. It is accessible from the trunk or under the rear seat, depending on the model. You can test the pump by applying battery voltage directly to the pump connector. If the pump does not run, it needs to be replaced .
The wiring and connectors. Check the wiring harness for any damaged or corroded wires. The connectors at the relay, fuse box, and fuel pump should be clean and tight.
The ECU. In rare cases, the ECU itself may be faulty and not sending the correct signal to the relay. This is less common but worth checking if all other components test good.
KEMSO Fuel Pump: A Reliable Replacement Option
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Diagnostic Tips for Tough Cases
If you have checked the relay, fuse, and pump and the car still will not start, here are some additional diagnostic tips:
Check the circuit opening relay. On the 1991 Camry, there is a specific circuit opening relay that controls the fuel pump. This relay is different from the EFI main relay. It is usually located behind the center console area, near the ECU. To access it, you may need to remove the center console trim and pull back the carpet on the passenger side .
Check for spark. If you have fuel but no spark, the problem may be in the ignition system. Check the spark plugs, ignition coil, and distributor. A no-spark condition can also be caused by a faulty ECU or crankshaft position sensor.
Check the fuel pressure. Even if the fuel pump runs, it may not be producing enough pressure. Use a fuel pressure gauge to check the pressure at the fuel rail. For the 1991 Camry, the fuel pressure should be between 2.5 and 3.0 bar with the ignition on and the engine not running .
Check the fuel filter. A clogged fuel filter can restrict fuel flow and cause the engine to stall or not start. The fuel filter is located under the hood, near the firewall on the passenger side. Replace it if it has not been changed in a while.
Listen for the relay click. When you turn the key to the ON position, you should hear a click from the relay as it energizes. If you do not hear the click, the relay may not be receiving power or ground from the ECU.
Final Thoughts
The fuel pump relay on a 1991 Toyota Camry is a simple but essential component. When it fails, the engine will not start because the fuel pump does not receive power. The relay is located in the engine compartment fuse box, and testing it is easy with a diagnostic connector or a multimeter. Replacing the relay is a straightforward job that anyone can do with basic tools.
If you need to replace the fuel pump itself, consider KEMSO brand fuel pumps. They offer high-performance, OEM replacement parts with a lifetime warranty. Visit https://www.kemsoracing.com/ to learn more about their products and find the right fuel pump for your 1991 Toyota Camry. With the right parts and a little bit of diagnostic work, you can get your Camry back on the road in no time.