The Complete Guide to 1991 Toyota MR2 Fuel Pump Replacement: Diagnose, Repair & Stay Running

Replacing a faulty fuel pump in your 1991 Toyota MR2 is a critical repair you can undertake yourself with the right preparation, tools, and safety precautions, restoring essential fuel delivery and engine performance. Ignoring a failing pump leads to stranding and engine damage. This detailed guide walks you through the entire process – from diagnosing a bad pump, gathering parts and tools, safely performing the removal and installation, to post-repair checks – empowering you to successfully complete this essential repair on your classic Japanese sports car.

Understanding the Fuel Pump's Role and Failure Symptoms

The electric fuel pump in your 1991 MR2 (specifically, models built on the SW20 chassis) is the heart of the fuel delivery system. Located inside the fuel tank, its primary job is to draw fuel from the tank and deliver it under consistent pressure (typically in the range of 35-45 PSI for non-turbo models, slightly higher for turbos) through the fuel filter to the fuel injectors. A properly functioning pump ensures the engine receives the precise amount of fuel required for combustion under all operating conditions – starting, idling, acceleration, and high-speed driving.

Failure symptoms are unmistakable and worsen as the pump deteriorates:

  1. Engine Cranking But Not Starting: The most common and obvious sign. The engine turns over normally but refuses to fire because no fuel reaches the cylinders.
  2. Engine Stalling: The car starts but dies shortly after, often after a few seconds or minutes, especially under load or when the pump heats up. This intermittent operation is a hallmark of a weakening pump motor.
  3. Loss of Power or Hesitation: During acceleration or while driving uphill, the engine lacks power, sputters, or hesitates significantly. This happens because the pump cannot deliver adequate fuel volume or pressure to meet demand.
  4. Engine Sputtering at High Speed/RPM: Similar to hesitation, but specifically occurring when maintaining highway speeds or at higher engine revolutions.
  5. Whining or Humming Noise from the Fuel Tank: A loud, unusual whining or buzzing sound coming from the rear of the car, particularly when the ignition is turned on (before starting) or while the engine is running, signals bearing wear or internal motor issues. A slight normal hum is standard; excessive noise is not.
  6. Surging: Unexpected and abrupt increases or decreases in engine speed while cruising at a steady throttle position, caused by erratic fuel pressure.
  7. Hard Starting When Warm: Difficulty restarting the engine shortly after shutting it down when it's at operating temperature, often related to vapor lock exacerbated by a weakening pump struggling to move warm fuel.

Confirming the Need for Replacement: Diagnosis First

Before undertaking the significant task of replacing the pump, confirming its failure is vital. Avoid unnecessary repairs by systematically checking:

  1. Verify Fuel Level: While seemingly basic, ensure there is ample fuel in the tank (over 1/4 full is recommended) before proceeding. Running the pump dry damages it.
  2. Check Inertia Switch: The 1991 MR2 has a fuel pump cutoff inertia switch designed to stop the pump in an accident. It's typically located in the rear trunk area near the shock tower or behind the interior trim. Ensure it hasn't tripped accidentally due to a bump or impact. Reset it by pressing the button on top.
  3. Listen for the Pump: Turn the ignition key to the "ON" position (do not start the engine). You should hear the fuel pump run for about 2-3 seconds to prime the system. A distinct humming sound should emanate from the rear (fuel tank area). Complete silence strongly points to a pump or circuit failure.
  4. Check Fuel Pressure: This is the definitive diagnostic step. You'll need a fuel pressure gauge kit designed for fuel injection systems.
    • Locate the Schrader valve on the fuel filter located near the front passenger side of the engine compartment (looks like a tire valve stem).
    • Relieve system pressure first! See the safety section below for the correct procedure.
    • Connect the gauge according to the kit's instructions.
    • Turn the ignition ON (or jumper the pump circuit - see below) to activate the pump. Observe the pressure reading.
    • Compare it to the factory specifications (consult a repair manual - generally 35-45 PSI for non-turbo, potentially 40-50+ PSI for turbo models at idle/full vacuum). Low or zero pressure confirms a pump or fuel delivery problem.
    • Watch if the pressure holds after the pump stops. A rapid drop could indicate a bad pump check valve, injector leak, or a pressure regulator issue (though pump is still the prime suspect if no pressure builds).
  5. Check Electrical Supply (if pump silent):
    • Locate the fuel pump relay in the main fuse/relay box in the engine compartment (check your owner's manual for precise location - often near the battery). Swap it with a known good relay of the same type (e.g., radiator fan relay).
    • Use a multimeter to check for 12V+ power at the fuel pump electrical connector located above the fuel tank access cover in the trunk floor. You will likely need to disconnect the connector. Have an assistant turn the key to ON while you probe the correct terminal (consult a wiring diagram - often the Black/Yellow wire is switched power).
    • Check for continuity on the ground circuit at the pump connector.
  6. Jumper the Pump (Confirmation Test): If electrical checks point towards the pump circuit being okay but the pump doesn't run during priming:
    • Locate the diagnostic connector under the hood (often a small black box near the fuse/relay box). It has terminals labeled FP and +B.
    • Connect FP and +B terminals together using a jumper wire or paperclip.
    • Turn the ignition key to ON. This bypasses the relay and ECU, supplying constant 12V+ directly to the pump if the rest of the circuit is good.
    • If the pump now runs (and wasn't running before jumpering), the problem lies before the pump (relay, ECU, wiring, inertia switch). If it still doesn't run with direct power jumpered, the pump itself is faulty.

Essential Tools and Replacement Parts

Gathering everything beforehand ensures a smoother process. Replacement fuel pumps for the 1991 MR2 are widely available.

  1. Replacement Fuel Pump: This is the core component. You have options:
    • OEM Toyota/Denso: The best quality, reliability, and fitment. Expensive but lasts the longest. The Denso part number is often the same as Toyota. Confirm for your specific model.
    • High-Quality Aftermarket: Brands like Bosch, ACDelco, Delphi offer reliable alternatives. Bosch pumps are common replacements and often recommended.
    • Budget Aftermarket: Can be significantly cheaper, but reliability and lifespan vary greatly. Proceed with caution; fuel pump failure leaves you stranded.
    • Pump-Only vs. Complete Sending Unit Kit: The original equipment pump is often sold as a pump-only module designed to attach to the existing fuel level sending unit assembly inside the tank. Highly recommended: Purchase a complete assembly kit that includes the fuel level sender (float arm) and sometimes a new strainer/filter sock and locking ring. This simplifies installation, ensures compatibility with the gauge, and addresses common sending unit failure points like worn rheostats (which cause inaccurate fuel gauge readings). Reusing old parts attached to the pump module is risky and often leads to premature failure or gauge issues.
  2. Recommended Consumables/Add-ons:
    • New Fuel Filter: Essential. Located in the engine bay, it traps debris that could damage the new pump and injectors. Replace it simultaneously.
    • New Strainer/Sock Filter: Included in most kits, but essential if not. Prevents debris from entering the pump.
    • O-Rings & Seals: Critical! The access cover gasket/seal and the seal for the fuel pump locking ring (if applicable). Fuel leaks are dangerous. Always use new seals. High-quality kits often include them.
    • Fuel Injector Cleaner: Adding a quality cleaner to the first tank of gas after replacement helps flush the system.
  3. Essential Tools:
    • Basic hand tools: Sockets (8mm, 10mm, 12mm, 14mm are common), wrenches, screwdrivers (Phillips #2/#3, JIS if possible, flathead).
    • Deep Well Sockets: Crucial for the fuel pump lock ring nut if replacing the entire assembly (typically a large nut requiring a 10" extension and deep socket – common sizes are 54mm, 62mm, or 3-1/8"). A large adjustable wrench or specialized pump lock ring removal tool might also work.
    • Fuel line disconnect tools (the correct size for late 80s/early 90s Toyota connectors). Plastic tools are safest. Avoid metal picks near fuel.
    • Jack and Jack Stands or Ramps + Wheel Chocks (ensure parking brake is firmly set first).
    • Safety Glasses & Nitrile Gloves (fuel resistant).
    • Fire Extinguisher (ABC type) readily accessible.
    • Drain Pan (for fuel spillage).
    • Large Rag/Towels for absorbing drips.
    • Shop Vacuum (optional, for debris cleanup around access area).
    • Pliers (needle nose, lineman's).
    • Wire Cutters/Crimpers & Butt Connectors or Soldering Iron/Solder/Heat Shrink (for electrical connection if necessary – best practice is soldering and heat shrink).
    • Multimeter (for verification).
    • Flashlight or Work Light.
    • Pry tool (plastic trim removal tool is ideal).
    • Penetrating oil (like PB Blaster) for stubborn bolts.
  4. Important Safety Gear (NON-NEGOTIABLE):
    • Proper Eye Protection: Gasoline splashes cause severe eye damage.
    • Chemical-Resistant Gloves (Nitrile): Protects skin.
    • Well-Ventilated Area: Never work in an enclosed garage without ventilation. Gasoline fumes are highly explosive and toxic. Use fans pushing fumes out.
    • No Ignition Sources: No smoking, sparks, open flames, pilot lights, or running engines nearby. Disconnect the battery negative terminal before starting work!

Crucial Safety Precautions for Fuel System Work

Working with gasoline demands utmost caution. A single spark can cause an explosion and severe injury or fire. Adhere strictly to these rules:

  1. Work Outdoors or in Extremely Well-Ventilated Area: Ideal: Outside, under a carport, or in a garage with doors fully open and forced ventilation if possible. Fume buildup is deadly.
  2. Eliminate ALL Ignition Sources: Prohibit smoking within 50 feet. Unplug battery chargers. Disconnect the battery negative terminal. Ensure no sparks from tools (use only hand tools – no power tools near the tank area). Ground yourself before touching components.
  3. Disconnect Battery Negative Terminal: The first step before any work begins. This prevents accidental sparking.
  4. Relieve Fuel System Pressure! This is critical before disconnecting any fuel lines.
    • Locate the fuel pump fuse or relay (check owner's manual – often labeled "EFI" or "Fuel Pump").
    • Start the engine and let it idle.
    • Carefully pull the fuel pump fuse or relay while the engine is running. The engine will sputter and die within a few seconds as fuel pressure depletes.
    • Turn the ignition OFF.
    • Crank the engine for 3-5 seconds to ensure any residual pressure is released.
    • Place a rag around fuel line connections before carefully disconnecting them to catch any residual fuel drips. Wear eye protection.
  5. Use Proper Containment & Cleanup: Have drain pans and large rags ready to catch spilled fuel immediately. Fuel evaporates quickly but leaves flammable residue. Dispose of rags properly outside after use. Do not use gasoline-soaked rags indoors. Clean spills promptly with detergent and water.
  6. Fire Extinguisher Ready: Keep a charged ABC fire extinguisher within immediate reach. Know how to use it.
  7. No Power Tools: Never use grinders, drills, or electric impacts near the fuel tank or during disassembly. Sparks are inevitable.
  8. Protect Skin and Eyes: Gasoline irritates skin and can be absorbed. Nitrile gloves offer good protection. Eye protection is mandatory.

Step-by-Step Guide: Removing the Old Fuel Pump (1991 MR2)

Access is gained through the rear trunk floor.

  1. Preparation: Park on a level surface. Disconnect the battery negative terminal. Gather all tools, parts, containers, and safety gear. Ensure ventilation. Relieve fuel pressure (as detailed above). Ensure the trunk is empty.
  2. Access the Fuel Pump Hatch: The fuel pump assembly is located under a large, round or square access panel in the trunk floor carpet. Remove trunk floor carpeting and trim pieces as necessary to expose a large metal access plate held down by several (usually 4-8) Phillips head screws or bolts. Use a large flathead screwdriver carefully for stubborn screws; penetrating oil may help. Pry up the cover gently with a pry tool if it sticks. Set screws aside safely.
  3. Clean the Area Thoroughly: Use a shop vacuum or compressed air to clean debris, dust, and road grime away from the access opening before removing the pump. Prevent any foreign material from falling into the tank. Lay clean rags around the opening.
  4. Disconnect Electrical Connectors: Find the main electrical connector plugged into the top of the fuel pump assembly or the fuel level sender. This connector supplies power to the pump and carries the fuel gauge signal. Carefully disconnect it (often involves pressing a release tab and pulling). There might be a secondary ground wire (black) attached to a screw nearby; note its position and remove the screw.
  5. Disconnect Fuel Lines: Two fuel lines connect to the top of the pump assembly/sender unit inside the access hatch:
    • Supply Line: The line delivering fuel TO the engine (often connected to the pump outlet).
    • Return Line: The line bringing unused fuel BACK to the tank from the engine bay regulator.
    • Identify: Use your finger to gently trace the lines back towards the front; the return line is usually smaller in diameter or follow the markings if present.
    • Disconnect: Press the safety tabs on the Toyota-specific plastic quick connectors inwards towards the connector body. While holding the tabs depressed, pull the connector straight off the metal fuel line nipple. Do NOT pull the lines. If extremely stuck, use the correct size plastic fuel line disconnect tool inserted between the connector body and the locking tabs to help release it. Have a rag ready as a small amount of residual fuel will drip out. Immediately cap or plug the disconnected fuel lines temporarily to minimize fumes and prevent debris entry. Protect the exposed pump outlets.
  6. Vapor/Vent Hoses (if applicable): Depending on the exact configuration of your 1991 model, there might be one or two smaller rubber vapor/vent hoses connected to the top of the sender unit assembly. These are typically held on by spring clamps or small hose clamps. Mark their positions (or take a picture) and carefully remove the clamps using pliers. Slide the hoses off the nipples.
  7. Remove the Pump Locking Ring: This secures the entire pump/sender assembly to the fuel tank.
    • Look for a large plastic nut (lock ring) with tabs around its perimeter. Do not confuse this with the metal ring underneath it.
    • Use the correct tool:
      • Deep Socket: The safest way. Identify the exact size (commonly 54mm, 62mm, or 3-1/8") and use a deep well socket on a long extension and breaker bar or long ratchet. Turn it COUNTERCLOCKWISE to loosen. Expect significant resistance; it might "crack" loose.
      • Special Tool: Some lock rings have a specific pattern usable with a purpose-made wrench.
      • Large Adjustable Wrench/Pliers/Large Screwdriver & Hammer (Last Resort): Carefully tap the notches counterclockwise gently with a brass drift punch or wood block to avoid cracking the ring. Avoid excessive force. Stripping this ring complicates removal significantly.
    • Unscrew the lock ring completely and set it aside. Note its orientation relative to the tank or assembly (a tab often fits a slot).
  8. Lift Out the Assembly: Carefully lift the entire fuel pump/sending unit assembly straight up and out of the fuel tank. Be prepared for fuel spillage from the pump housing and soaked sock filter. Have rags and a drain pan ready. Tip it slightly to drain excess fuel back into the tank. Do not let the float arm (fuel level sender) catch on the tank opening. Note the assembly's orientation – a locating tab on the tank flange usually aligns with one on the assembly base. Take pictures or mark alignment points if needed.
  9. Remove Pump from Sending Unit (if replacing only pump): Only if you purchased a pump-only module AND are confident the sender is good:
    • Note all hose connections and wiring points between the pump and the sender bracket.
    • Disconnect small rubber hoses (often inlet and outlet). May have clamps.
    • Carefully disconnect the power and ground wires to the pump itself (often soldered or spade connectors).
    • Unclip or unbolt the pump from the bracket/hanger assembly.
    • Recommendation: Avoid this complexity unless absolutely necessary and the sender is proven reliable. Replacing the entire assembly is preferable.

Step-by-Step Guide: Installing the New Fuel Pump Assembly

  1. Prepare the New Assembly:
    • Compare it visually to the old unit for exact match.
    • Transfer Components (if needed): If the new kit didn't include a strainer/sock filter, carefully transfer the new one onto the pump inlet. Ensure it's secure. Transfer the outlet fitting/collar if applicable. Double-check all O-rings are present on the assembly base and ports. Lubricate ALL O-rings and seals lightly with clean engine oil or vaseline only. Avoid petroleum jelly near critical rubber. Do not lubricate the locking ring seal groove.
    • Electrical Connection: If the new pump came separate (not pre-wired to the sender), you must connect its wires to the harness on the hanger assembly. Soldering and sealing with heat shrink tubing is the most reliable method. Twist-splice connectors (e.g., barrel connectors) are acceptable if properly crimped and sealed with heat shrink. Ensure polarity is correct (typically + and - are marked on the pump; match to the assembly harness).
  2. Prepare the Tank Opening: Clean the sealing surface on the tank flange meticulously. Remove any old gasket material, dirt, or debris using a clean rag. Inspect the tank opening seal and the groove in the locking ring. Ensure both are spotless and dry.
  3. Position the New Assembly: Carefully lower the new (or rebuilt) pump/sender assembly down into the fuel tank. Align the locating tabs correctly (match the marks you made earlier). Ensure the float arm moves freely and isn't kinked. Push the assembly flange down firmly against the tank seal surface so it sits fully flush and level.
  4. Install the Locking Ring Seal: Take the new sealing O-ring or square-ring for the locking ring. Clean and lightly lubricate it with clean engine oil. Place it exactly in the groove around the neck of the pump assembly flange. Ensure it isn't twisted. It must fit perfectly into the groove.
  5. Hand-Tighten the Locking Ring: Place the large locking ring over the assembly neck. Carefully thread it on by hand COUNTERCLOCKWISE (yes, counterclockwise - this can be counter-intuitive; turning it clockwise initially might thread it slightly onto the ring, but securing requires turning against its normal removal direction - counter-clockwise to tighten it). Align the tabs/slots correctly. Finger-tighten as much as possible, ensuring it stays seated properly on the new seal. Do not use tools yet. Ensure the assembly flange remains flat against the tank surface and the seal is compressed between the ring and the tank flange.
  6. Final Tighten the Locking Ring: Using the deep socket, locking ring tool, or adjustable wrench, tap the ring COUNTERCLOCKWISE firmly but cautiously. You want it tight enough to compress the seal sufficiently to prevent leaks, but overtightening can crack the plastic ring or distort the metal tank flange. Tighten approximately 1/8 to 1/4 turn after snug. Listen/feel for resistance increase indicating seal compression. Avoid excessive force. If a torque specification is available, use it.
  7. Reconnect the Hoses: Connect the vapor/vent lines first (if applicable), securing them with their new clamps or existing spring clamps in their original positions.
  8. Reconnect the Fuel Lines: Identify the supply and return lines correctly. Remove any temporary caps/plugs. Ensure the connector release tabs are unlocked. Push each connector firmly and squarely onto its respective metal nipple on the pump assembly. You should hear and feel a distinct "click" as the internal locking tabs engage. Tug firmly on the connector to ensure it's fully locked. Failure to connect securely will cause immediate, dangerous fuel leaks.
  9. Reconnect Electrical: Plug the main electrical connector firmly back into the sender unit/pump assembly. Reattach the ground wire securely to its mounting screw point nearby. Ensure all connections are secure and protected from chafing.
  10. Verify Connections: Visually double-check all hoses, lines, and electrical connections are securely attached. Ensure the locking ring is tight. Ensure no tools or rags are left inside the access area.
  11. Reinstall Access Cover: Carefully clean the mounting surface of the access plate and the car's body. Place the access cover back over the opening. Install and tighten all screws/bolts securely. Replace trunk carpeting and trim panels as needed.

Post-Installation: Testing and System Priming

  1. Final Visual Check: Before reconnecting the battery, perform one last inspection around the pump access area for any obvious leaks, dangling wires, or forgotten tools.
  2. Reconnect Battery: Reconnect the battery negative terminal securely.
  3. Key ON - Pump Priming: Turn the ignition key to the "ON" position (do not start). Listen carefully for the new fuel pump to run for its standard 2-3 second prime cycle. You should hear its characteristic hum from the rear. This builds initial fuel pressure. Perform this step 2-3 times (Key ON, listen, wait 10 seconds, Key OFF, repeat) to ensure the system pressurizes fully.
  4. Check for Leaks - Stage 1: Carefully inspect the top of the fuel pump assembly visible through the access hole (don't stick your head directly over it - look from the side) and along the fuel lines near their connections. Use a mirror and flashlight if needed. LOOK and SMELL. Are there any drips or the strong odor of gasoline? If you see or smell ANY leak, IMMEDIATELY turn the key OFF. Do not start the engine. Fix the leak immediately.
  5. Start the Engine: Assuming no leaks, crank the engine. It might take slightly longer to start than usual (up to 10 seconds) as air is purged from the lines and fuel fills the rail. Be patient. Once it starts, listen for unusual noises from the pump. A steady hum is normal; whining, grinding, or screeching are not.
  6. Check for Leaks - Stage 2: With the engine running, carefully re-inspect all fuel line connections at the pump, the vapor lines, and the sealing ring under the locking ring for leaks. Also check the area under the car near the tank and along the lines running forward. Pay extreme attention. Engine heat increases risk.
  7. Check Fuel Gauge Operation: Observe the fuel gauge on the instrument cluster. It should accurately reflect the fuel level in the tank (if you installed a new sending unit assembly). If it reads empty or full incorrectly, there could be an issue with the sender or gauge circuit (often needing to drive a short distance to stabilize).
  8. Test Drive: Once satisfied there are no leaks and the engine runs smoothly at idle, take the car for a short, cautious test drive. Pay close attention to:
    • Smooth starting (hot and cold).
    • Smooth acceleration without hesitation.
    • Ability to maintain highway speeds steadily.
    • Absence of engine stalling.
    • Normal sounding pump operation.
  9. Retorque and Final Inspection: After the test drive and the engine has cooled down significantly, perform one final visual inspection for any signs of weeping fuel around connections or at the pump access seal.

Potential Issues & Troubleshooting Post-Installation

Even with careful installation, minor issues can arise:

  1. Engine Doesn't Start After Installation:
    • Verify fuel pump priming (Key ON: Listen for pump hum).
    • Recheck all electrical connectors are fully plugged in (main plug at pump, inertia switch).
    • Double-check main electrical plug orientation – did you plug it in backwards? (Unlikely due to shape).
    • Confirm the inertia switch is still reset.
    • Verify fuel lines are connected to the correct ports (Supply vs. Return swapped?).
    • Check fuel pump fuse (did you blow it?).
    • Verify fuel line connectors fully "clicked" and locked onto the pump nipples.
    • Ensure the locking ring is tight enough, compressing the seal properly.
    • Use the FP/+B jumper method described earlier to verify pump operation. If it runs jumpered, check relay/ECU circuit.
    • If pump runs but no start, recheck fuel pressure at the rail Schrader valve.
    • Consider air trapped in fuel rail – crank longer while gently pressing throttle.
    • Did you forget to replace the fuel filter and it's now clogged with debris dislodged during pump replacement? (Change it!).
  2. Fuel Gauge Reads Incorrectly (after new assembly install):
    • Did the assembly get installed rotated? Ensure locating tab alignment.
    • Defective new sending unit – test resistance across sender terminals while moving float arm slowly (consult manual for Ohms vs. level specs).
    • Poor ground connection at the sender or instrument cluster.
    • Faulty instrument cluster gauge.
  3. Fuel Leak Observed:
    • IMMEDIATELY STOP THE ENGINE!
    • Visually pinpoint the leak source:
      • Locking Ring Seal Area: Was a new seal used? Was the sealing surface clean and dry? Was the ring tightened correctly?
      • Fuel Line Connections: Did they click fully? Are the safety tabs engaged? Is an O-ring missing or damaged?
      • Vapor Hoses: Are they fully seated and clamped?
      • Pump Outlet Fittings (if applicable): Did you transfer/screw them correctly?
    • Identify source and rectify immediately. Do not drive. Replace damaged components. Ensure surfaces are clean.
  4. Unusual Pump Noise (Whining/Grinding/Screeching):
    • Did the pump sit without fuel? Running dry, even briefly, damages it.
    • Was the inlet strainer fully submerged during priming? Running above fuel momentarily causes noise.
    • Possible faulty or defective replacement pump.
    • Is there a restriction in the fuel line (e.g., kink, clogged filter)? Check fuel pressure.
  5. Engine Runs Rough, Hesitates, or Lacks Power:
    • Verify fuel pressure with gauge. Low pressure can be a bad regulator (less likely), incorrect pump application, clogged filter, or restriction.
    • Ensure air is purged from the system (drive more).
    • Check for vacuum leaks unrelated to fuel pump work.
    • Run injector cleaner through a full tank.
    • Consider if the old fuel filter is severely clogged (replace it!).

Essential Maintenance Tips and Longevity

  1. Replace Fuel Filter Regularly: Follow Toyota's severe service interval – change the inline fuel filter every 15,000-30,000 miles. A clogged filter forces the pump to work much harder, shortening its lifespan significantly.
  2. Keep the Tank Clean: Avoid running the car perpetually on low fuel. Sediment settles at the bottom and gets sucked into the pump strainer. Aim to refill when the tank reaches 1/4 full. Periodically adding a quality fuel injector cleaner helps keep the entire system (including pump and sock filter) clean.
  3. Use Quality Fuel: While fuel quality varies, sticking with Top Tier detergent gasoline certified retailers (when available) can help minimize deposits. Avoid consistently contaminated stations. Use the correct octane rating as specified in your owner's manual (usually 87 for non-turbo).
  4. Address Surging/Hesitation Promptly: These can be early signs of a weakening pump. Diagnosing early allows you to replace it before complete failure strands you. Perform a fuel pressure test if symptoms arise.
  5. Prevent Water Contamination: Avoid filling up during tanker deliveries at gas stations (stirs sediment). Ensure your fuel filler cap seal is intact. Contaminated fuel (water) can damage pump components.

Replacing the fuel pump in your 1991 Toyota MR2 is a significant task, but entirely achievable with patience, preparation, and strict adherence to safety protocols. Following this comprehensive guide empowers you to diagnose the fault, source quality parts, perform the repair safely and effectively, and ensure your classic sports car continues to run reliably for many more miles. Remember, safety is paramount when working with gasoline; never compromise on ventilation, ignition sources, or system pressure relief. Your diligence ensures a successful outcome and the continued enjoyment of this iconic Japanese automobile.

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