1991 Toyota Camry Fuel Pump Relay Location & Ultimate Troubleshooting Guide

Finding the fuel pump relay in your 1991 Toyota Camry is straightforward: it's inside the relay box located just above the passenger footwell area near the firewall. Accessing it requires removing a small trim panel.

The seemingly simple task of locating the fuel pump relay in a 1991 Toyota Camry is crucial. This small electrical component acts as a switch, controlled by the engine computer, that sends high-power battery voltage to the fuel pump when you turn the ignition key to "Start" or "Run." If this relay fails, the fuel pump won't activate, meaning your Camry won't start or will stall unexpectedly after running briefly on residual pressure. Knowing precisely where to find it and how to confirm its status is essential for diagnosing and fixing common no-start or fuel delivery issues with this classic sedan.

The Exact Location: Passenger Footwell Relay Box

The primary relay box for engine-related components, including the fuel pump relay, on the 1991 Camry is situated within the passenger compartment. Here’s how to find and access it:

  1. Position: Open the passenger side front door. Look at the far right side (towards the center of the car) of the passenger footwell area. Specifically, look up and slightly towards the center console near where the bottom of the dashboard meets the transmission hump and firewall. The relay box is mounted vertically on the inside of this structural support.
  2. Cover: This small rectangular or square-shaped black plastic relay box will have a removable cover. The cover typically snaps into place. You won't see individual relays until this cover is removed. It might be partially obscured by the carpet edge or other trim components.
  3. Accessing it:
    • Remove any floor mats.
    • Gently pull the edge of the passenger side carpeting away from the transmission hump and firewall area in the footwell. You may need to temporarily tuck it back to get clear visibility and working space.
    • Locate the small vertical section of interior trim panel covering the relay box mounting area on the side of the transmission tunnel. This panel is usually made of dark plastic or vinyl and matches the lower dashboard.
    • Remove the Trim Panel: This panel is secured by plastic clips or small Phillips-head screws, often found at the top and bottom edges. Carefully pry off any clips using a trim removal tool or a flat-head screwdriver wrapped in cloth to prevent scratches. Remove any screws. Set the panel aside.
    • See the Box: With the panel removed, the black plastic relay box should now be fully visible, mounted directly onto the metal body structure.
    • Remove the Relay Box Cover: Locate the small tabs on either side (or top/bottom) of the relay box cover. Gently squeeze these tabs inward while simultaneously pulling the cover straight off towards you. Set the cover aside.
  4. Identifying the Fuel Pump Relay: Inside the relay box, you'll see several similar-looking relays plugged into sockets. Relays in older Toyotas like the '91 Camry are usually small cubes, often blue, black, or yellow, with multiple electrical blade terminals underneath. The specific relay you need might have a label on the relay box cover (though these often fade or become illegible). Crucially, look for labeling printed on the plastic relay box housing itself or molded into the plastic near each relay socket. Common labels used by Toyota include:
    • "FUEL PUMP" (Most direct)
    • "FP" (Abbreviation)
    • "CIRCUIT OPENING RELAY" (COR - Toyota's common name for this function). On the 1991 Camry, look for "CIRCUIT OPENING RELAY" printed on the relay box near the socket. This is your fuel pump relay.
    • If labels are missing, compare your relay layout to verified diagrams found in a factory service manual (FSM) or highly reputable repair database (like ALLDATA or Mitchell1 - note the brand of reliable source).
  5. Relay Removal: Once positively identified, grasp the fuel pump relay firmly near its base and pull it straight out from its socket. It may require a bit of effort if it hasn't been removed in a long time.

What Does the Fuel Pump Relay Do? Understanding its Role

Before diving into troubleshooting, it's critical to understand precisely what the fuel pump relay does and how its function differs from the fuel pump fuse:

  1. Function: The fuel pump relay is a remotely controlled, heavy-duty electrical switch. Its primary job is to manage the high electrical current (amperage) required by the electric fuel pump. Drawing this current directly through the ignition switch or engine computer would overload those components.
  2. Control Signal: The engine computer (ECU) determines when the pump needs power. When you turn the key to "Start" or "Run," the ECU sends a small, low-current ground signal to the relay's control coil circuit. This is the "on" command.
  3. Power Switching: This small control signal activates an electromagnet (the coil) inside the relay. The electromagnet pulls internal contacts closed. These closed contacts complete the much larger "power circuit," allowing full battery voltage to flow through the relay from its power source terminal (fuse), out its output terminal, and down to the fuel pump itself.
  4. Safety: Initial Prime: When you first turn the key to "Run" (before cranking), the ECU typically energizes the relay for just 1-2 seconds to "prime" the fuel system and build pressure for starting. If the engine doesn't start within a few seconds, the ECU de-energizes the relay as a safety measure to prevent flooding and pump damage. Once the ECU detects cranking or engine running (via a signal from the distributor), it keeps the relay energized continuously.
  5. Relay vs. Fuse: It's vital to understand the difference:
    • Fuel Pump Relay: Controls when the pump receives power. A faulty relay means no power when commanded.
    • Fuel Pump Fuse: Provides primary circuit protection against overcurrent (shorts, overloads). A blown fuse breaks the circuit entirely. Both a blown fuse and a failed relay will prevent the pump from running. Always check the fuse first (located in the Main Under-Hood Fuse Box near the battery) as it's easier.

Symptoms of a Faulty Fuel Pump Relay (1991 Camry)

A malfunctioning fuel pump relay in your '91 Camry will directly prevent fuel delivery to the engine. The symptoms often mimic a completely failed fuel pump or ignition problem:

  1. Engine Cranks But Won't Start: This is the most common symptom. The starter turns the engine over, but there's no fuel reaching the injectors because the pump isn't running.
  2. Engine Stalls Suddenly After Starting: The relay may initially function when cold but fail as it heats up internally. The car may start and run briefly, then stall abruptly a few seconds or minutes later. It may not restart until the relay cools down (a characteristic sign of relay failure). Cooling time can range from minutes to an hour.
  3. No Sound from the Fuel Tank at Key-On: When you turn the ignition key to "Run" (don't crank), you should hear a distinct whining or humming sound for 1-2 seconds coming from the rear of the car (under the back seat). This is the pump priming. If you hear nothing, it points towards a power problem upstream of the pump itself – a blown fuse or a bad relay/ECU command. Always check the relay/fuse circuit before condemning the pump. Access the pump area by folding down the rear seat bottom cushion.
  4. Lack of Fuel Pressure: The most definitive test for a fuel delivery problem is checking the Schrader valve pressure test port on the fuel injector rail. If there's no pressure after turning the key to "Run" or during cranking, it confirms fuel isn't being delivered, implicating the pump, relay, fuse, or wiring. This requires a fuel pressure gauge compatible with the valve fitting.
  5. Intermittent Starting Problems: Random failures to start, seemingly without pattern, can be a symptom of a relay with failing internal contacts that only sometimes make a connection. The engine may sometimes crank and start normally, other times it cranks without starting. This unpredictability is highly frustrating.
  6. Check Engine Light (CEL): While not exclusive, a failing relay might sometimes cause the ECU to set a diagnostic trouble code (DTC) related to fuel system issues or circuit problems. However, the '91 Camry's OBD-I system is less comprehensive than modern cars, so the absence of a CEL doesn't rule out the relay. Use an OBD-I code reader specific to Toyota if the light is on.

Testing the 1991 Camry Fuel Pump Relay (Step-by-Step)

You can perform several checks to determine if the relay itself is the culprit after confirming the fuel pump fuse is good. Disconnecting the battery negative terminal is recommended safety practice before testing.

  1. Initial Swapping Test (Simple Check):

    • Locate another identical relay in the same passenger footwell relay box (e.g., the EFI Main Relay, Fan Relay, or possibly the Horn Relay). The "CIRCUIT OPENING RELAY" is usually identical in design and terminal layout to the EFI Main Relay in this generation.
    • Swap the suspected fuel pump relay with a known working relay of the same type.
    • Attempt to start the car. If the problem disappears (pump primes, car starts), the original relay is bad. If the problem persists, the relay is likely not the issue (but double-check fuse power).
    • This test is only valid if the relay you swapped in is known to be good for its own function.

  2. Basic Physical and Auditory Test (Power Cycling):

    • Remove the relay (as per the location steps above).
    • Reconnect the battery negative terminal.
    • Have a helper turn the ignition key to the "Run" position.
    • Listen: You might hear a faint audible "click" sound from the relay socket area if the ECU is correctly trying to energize the relay's control coil. Lack of a click does not definitively condemn the relay; it could be a problem with the ECU's signal or wiring to the control side of the socket. A click confirms the control circuit is at least trying to activate.
    • Observe: Plug the relay back into its socket firmly. Have the helper cycle the key "Off" -> "Run". You should feel and potentially hear a distinct "click" from inside the relay itself as it energizes (when key turned to "Run") and de-energizes (when key turned back to "Off"). Lack of a tactile "click" strongly suggests an internal failure within the relay.

  3. Multimeter Continuity Test (Power Circuit - Requires Relay Removal):

    • Disconnect the Battery Negative Terminal. Crucial for safety.
    • Remove the relay.
    • Identify the Relay Terminals: Look at the bottom of the relay. It will have 4 or 5 metal blade terminals. Find the diagram printed on the relay body or use a known diagram source. For the '91 Camry Circuit Opening Relay, the standard configuration is two larger terminals (usually designated 30 and 87) for the high-current power circuit and two smaller terminals (usually 85 and 86) for the control coil.
    • Test Resistance Across Control Coil (85 & 86):
      • Set your digital multimeter to measure Ohms (Ω - Resistance).
      • Place one probe on terminal 85 and the other on terminal 86.
      • A good relay coil typically shows resistance between 50-120 Ohms (check relay specifics if possible). Significantly higher resistance (OL / Open Circuit) or zero resistance indicates a faulty coil.
    • Test Power Circuit Continuity (Normally Open - 30 & 87):
      • With the meter still on Ohms.
      • Place one probe on terminal 30, the other on terminal 87.
      • With the relay OFF: There should be NO continuity (Meter shows OL / Open Circuit). The internal contacts are open.
      • Activate the Relay Manually: Apply direct power to the control coil. You need a fused jumper wire set and a known voltage source like your car battery (or a spare 12V battery):
        • Carefully connect Battery Positive (+12V) to relay terminal 86.
        • Carefully connect Battery Negative (Ground) to relay terminal 85. CAUTION: Ensure probes don't touch other terminals. Use wires with clips if possible.
      • With the relay ON (Coil Energized): Place one probe on terminal 30, the other on terminal 87. The meter should now show CONTINUITY (near 0 Ohms). If it still shows Open Circuit, the internal power contacts are burned out or stuck open.
    • NOTE: Some relays may have a diode across the coil for voltage spike suppression. This can cause an initial continuity reading that then drops as the multimeter charges the internal capacitor. Refer to your meter manual.

  4. In-Socket Voltage Testing (Confirms Power & Signals - Advanced):

    • Reconnect the Battery Negative Terminal.
    • Remove the relay cover but plug the relay back into its socket fully. This test requires the relay to be plugged in.
    • Set your multimeter to measure DC Volts (20V scale).
    • Test Constant Battery Voltage (Terminal 30 Power Source):
      • Identify the terminal 30 wire pin in the socket (use diagram/wire colors from FSM: Often Black wire with Red stripe / Black/Red).
      • Touch the meter BLACK (negative) probe to a known good ground point (unpainted metal on body or engine).
      • Touch the meter RED (positive) probe to the metal socket terminal for terminal 30 (back-probe carefully without shorting to adjacent pins). You should read Battery Voltage (approx. 12.5V) at ALL TIMES (Key On or Off). No power here indicates a blown fuse or wiring fault upstream.
    • Test ECU Control Signal (Terminal 85 Ground - Key ON/Run):
      • Identify terminal 85 socket pin (Often Light Green wire with White stripe / Light Green/White).
      • Touch meter RED probe to this socket pin (careful back-probe).
      • Touch meter BLACK probe to a known good ground.
      • Turn ignition key to the "Run" position (Do Not Crank).
      • You should read Battery Voltage ONLY for the initial 1-2 seconds when the key is first turned to Run. This indicates the ECU is providing the ground path (through its internal switch) for a short time to activate the relay. The voltage you're measuring is battery power pulled through the relay coil and down to ground via the ECU.
      • If voltage is present longer than 2 seconds without cranking, that's incorrect. If voltage is never present, the ECU may not be commanding the relay, or there's an open in the ground control path wiring.
    • Test Switched Power to Relay Coil (Terminal 86):
      • Identify terminal 86 socket pin (Often Blue wire with White stripe / Blue/White or Red/White).
      • Touch meter RED probe to this socket pin.
      • Touch meter BLACK probe to ground.
      • Turn ignition key to the "Run" position. You should read Battery Voltage continuously while the key is in "Run". This is the ignition-switched +12V source feeding the other side of the relay coil. Loss of power here indicates an ignition switch or wiring issue.
    • Test Relay Output Power to Fuel Pump (Terminal 87):
      • Identify terminal 87 socket pin (Often Blue wire with Black stripe / Blue/Black).
      • Touch meter RED probe here.
      • Touch meter BLACK probe to ground.
      • Turn ignition key to the "Run" position.
      • You should read Battery Voltage at terminal 87 only for the 1-2 seconds that the pump primes. This reading confirms the relay is switching power from Terminal 30 to Terminal 87 as commanded. Lack of power here with good input power and ECU signal points directly to the relay.

Replacing the Fuel Pump Relay (1991 Toyota Camry)

Once you've confirmed the relay is faulty:

  1. Obtain the Correct Replacement:

    • Toyota Genuine Part: The most reliable option. Use the part number found on your old relay or consult the dealer/Toyota parts catalog. Common Toyota numbers for this era Circuit Opening Relay include 28300-** series part numbers. Know the exact relay type.
    • High-Quality Aftermarket: Brands like Denso (Toyota's primary supplier), Bosch, or Standard Motor Products (SMP) are generally reputable. Avoid the absolute cheapest options.
    • Take the Old Relay: Physically match the replacement. Ensure the terminal pattern (4 or 5 blade locations) and plastic base shape are identical. Confirm any critical specifications (amperage rating, voltage, coil resistance if listed) are the same or exceed the original.

  2. Disconnect Battery Negative Terminal: Always disconnect power before working on electrical components to prevent sparks and potential damage.

  3. Access the Relay: Follow the location steps above to remove the trim panel and relay box cover.

  4. Remove the Bad Relay: Grasp the relay firmly near its base and pull it straight out of the socket. Rocking slightly may be necessary if it’s stuck. Avoid pulling by the plastic cover only.

  5. Install the New Relay:

    • Align the new relay's terminal blades exactly with the socket slots.
    • Push the relay straight down firmly into the socket until it seats completely. You should feel and hear it click into place.
    • Ensure the relay is fully seated – misalignment or partial insertion can cause poor contact and malfunctions.

  6. Reinstall Components: Replace the relay box cover. Snap or screw the interior trim panel back into position over the relay box. Tuck the carpeting back neatly.

  7. Reconnect Battery Negative Terminal: Secure the clamp tightly.

  8. Test Operation:

    • Turn the ignition key to "Run". You should hear the fuel pump prime for 1-2 seconds.
    • Start the engine. It should start and run normally.
    • Monitor for the initial problem (stalling, no start) recurring in the short term.

Choosing the Right Replacement Relay

For longevity and reliability, prioritize these options:

  • Toyota OEM (Genuine): Manufactured to exact specifications. Highest cost, but most assurance of compatibility and durability. Obtain through Toyota dealership parts counters or reputable online Toyota parts sellers.
  • Denso (Original Supplier): Denso often manufactured the original relays installed on Toyotas at the factory. Their aftermarket relays are typically identical to OEM and offer excellent quality at a slightly lower price point. Denso is consistently recommended by mechanics for Toyota electrical parts.
  • Reputable Aftermarket Brands (e.g., Bosch, Standard Motor Products): Major suppliers with solid reputations in the automotive parts industry. Ensure you purchase from authorized sellers to avoid counterfeits. Quality is generally good, though variation can sometimes occur. Bosch relays are widely respected globally.
  • Avoid: Generic "no-name" or excessively low-cost brands. These frequently suffer from poor contact materials, weak internal springs, and inferior plastic housings prone to cracking or heat distortion. They may work initially but often fail prematurely, leaving you stranded again.

Beyond the Relay: Other Causes of Fuel Pump No-Power

If replacing the relay doesn't solve the problem, investigate these other potential causes systematically:

  1. Blown Fuel Pump Fuse: Always the first thing to check (often a 15A or 20A fuse). Located in the Main Fuse Box under the hood near the battery. Find the fuse labelled "EFI," "FUEL PUMP," or "INJ."
  2. Bad Fuel Pump Itself: The pump motor can burn out. Test using the fuel pressure port on the rail. If no prime sound and you have confirmed power at terminal 87 of the relay socket (for 1-2 seconds at Key ON), the pump or its wiring/in-tank harness is likely bad. Accessing the pump requires removing the rear seat bottom cushion and opening an access panel in the floor.
  3. Fuel Pump Wiring Faults: Damaged, corroded, or broken wiring between the relay output (Terminal 87), the underbody harness connection, and the fuel pump itself. Common failure points include connectors near the relay box, grommets passing through the firewall or floor, and in the trunk/under seat areas where wires can chafe. Check for voltage drop along the circuit.
  4. Faulty Engine Control Unit (ECU): The ECU may not be sending the ground signal to terminal 85 to activate the relay. Diagnosing this requires specialized knowledge and verifying ECU inputs/outputs. Consult factory wiring diagrams and pinout tests. This is less common than other failures but possible.
  5. Faulty Ignition Switch: If there's no power to the relay control coil (Terminal 86) in the "Run" position, a malfunctioning ignition switch could be interrupting the ignition-switched +12V supply to multiple critical components. Check for power at terminal 86 per the testing section above.
  6. Bad Ground Connections: The fuel pump requires a good ground path to function. Corrosion or looseness at the pump ground strap/wire (under rear seat near pump), the engine ground strap, or the main battery ground can cause intermittent or complete failure. Visually inspect connections, clean terminals, and ensure tightness.
  7. Damaged EFI Main Relay: The EFI Main Relay (also located in the passenger footwell relay box) powers the ECU itself and often other fuel injection components like injectors and sensors. If this relay fails, the ECU has no power to command the fuel pump relay. Test or swap the EFI Main Relay (usually identical to FP relay) as described earlier. Observe the ECU lights and check for any ECU power.

Maintenance Tips for Your 1991 Camry's Fuel System

Preventive measures can extend the life of your fuel pump relay and entire fuel system:

  1. Regular Relay Inspection/Cleaning: Periodically (e.g., during oil changes), access the relay box. Remove the cover. Unplug and firmly reseat each relay one by one. This action scrapes minor corrosion off terminals, ensuring good electrical contact. Visually check relays for signs of excessive heat damage (melting plastic, severe discoloration, burnt smell). Use electrical contact cleaner if terminals look dirty/corroded. Protect other components with a rag.
  2. Keep Connections Clean and Dry: Ensure the relay box area is clean and dry. Moisture ingress corrodes terminals over time. Verify the weather stripping around doors and the firewall is intact to prevent water leaks into the footwell. Address leaks promptly.
  3. Use Quality Fuel: Consistently using major brand fuel helps prevent contamination and undue strain on the fuel pump.
  4. Avoid Constant Low Fuel: Running the tank consistently very low makes the fuel pump work harder (fuel cools it) and increases the risk of sucking sediment from the bottom of the tank into the pump strainer. Keep tank at least 1/4 full when possible.
  5. Replace Fuel Filter: A clogged fuel filter forces the pump to work much harder to push fuel, increasing electrical current draw and stressing the pump windings and relay contacts. Replace the inline fuel filter according to your maintenance schedule (typically 15,000-30,000 miles). Find the filter under the car, usually near the tank or along the frame rail.

Conclusion: Mastering Fuel Pump Relay Access in Your 1991 Camry

Successfully locating, testing, and replacing the fuel pump relay in your 1991 Toyota Camry is a manageable DIY task that can save significant time, diagnostic expense, and frustration. Remember the key steps: Identify the relay box above the passenger footwell near the firewall/transmission hump, remove the trim panel, open the box cover, and locate the relay labelled "CIRCUIT OPENING RELAY" on the box housing itself. Always verify the condition of the fuel pump fuse first using the fuse tester or multimeter continuity function. Employ swapping, power cycling, and multimeter testing techniques outlined to confirm relay function. Prioritize genuine Toyota or Denso parts for replacement reliability. By understanding this vital component's role and symptoms of failure, you empower yourself to troubleshoot fuel delivery issues effectively and keep your reliable '91 Camry running smoothly for years to come.

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