1990 Volvo 740 Fuel Pump Relay Location: Find & Fix It Fast (Complete Guide)

Your 1990 Volvo 740's fuel pump relay is located inside the trunk. Specifically, it is mounted on a metal bracket attached to the vertical metal frame behind the left side interior trunk panel trim (the driver's side in left-hand-drive cars). You must remove the large, felt-like trunk liner panel on that side to access it. The relay itself is typically a white or tan plastic box with electrical terminals on the bottom and often has the number "207" stamped on it. This is the critical relay responsible for powering the fuel pump when you turn the ignition key.

Location Details: Trunk Mounting

  • Exact Spot: Look for the relay behind the large, felt-covered interior trim panel on the left inner fender wall of the trunk (driver's side for LHD models). It is not visible with the panel in place.
  • Access Method: To see the relay, you must remove this panel. It is usually held in place by plastic push-pins or metal clips around the edges and sometimes a screw or two near the top where it meets the rear shelf trim. Carefully pry out the clips/screws and pull the panel away from the metal bodywork. The relay is mounted directly to the metal behind this panel.
  • Relay Appearance: The fuel pump relay is commonly a white or tan plastic cube, roughly 1.5 inches square, with several metal terminals protruding from its base. It plugs into a socket attached to the metal bracket. Look for the identifying number "207" on its top or side – this is the standard Bosch part number for the fuel pump relay in this era of Volvo 740s. Other relays in the car may have different numbers (like 100, 102, 103, etc.).

Function: Why the Relay Matters
The fuel pump relay acts as an electrical switch controlled by the ignition system and engine control computer (ECU). Its primary function is to supply high-current electrical power to the fuel pump only when required – specifically when the ignition is turned on (priming) and while the engine is cranking or running. When you turn the key to the "run" position or start cranking, a small signal from the ignition switch or ECU activates an electromagnet inside the relay. This electromagnet pulls internal contacts closed, completing the high-amperage circuit that sends full battery power to the fuel pump. If this relay fails, the fuel pump receives no power, leading directly to a no-start condition.

Symptoms of Failure: When to Suspect the Relay
A failing or failed fuel pump relay in your 1990 Volvo 740 will almost always result in an engine that cranks normally but refuses to start. There are other possible causes, but the relay is a common and critical suspect. Watch for these key symptoms:

  1. Cranks But Won't Start: The most definitive sign. The starter motor spins the engine, but there is no firing or attempt to run. The engine simply keeps cranking without starting.
  2. No Fuel Pump Sound: Listen carefully near the fuel tank (rear of the car) when you first turn the ignition key to the "run" position (before cranking). You should hear a distinct buzzing or humming sound for about 1-2 seconds as the pump primes the system. Complete silence from the fuel pump area is a strong indicator of either relay failure, fuse failure, pump failure, or wiring breaks. Lack of sound alone doesn't isolate the relay, but it points strongly to the fuel delivery circuit.
  3. Engine Dies While Driving: A relay that becomes intermittent may suddenly cut power to the fuel pump while driving. This causes the engine to die immediately as if the ignition was turned off. It might restart after cooling down or being jiggled, then fail again unpredictably.
  4. Intermittent Starting Problems: The car starts fine sometimes but refuses to start on other attempts, particularly after being warm, sitting briefly, or during specific weather conditions. This points to electrical issues like a failing relay.
  5. No Spark (Sometimes): While the relay primarily powers the pump, its failure will prevent the engine from running regardless of spark presence. However, some 740s use the same relay output signal to also power the ignition system components (like the power stage). A completely dead relay can cause both no fuel and no spark, preventing any chance of starting.

Precautions: Safety First
Working on the fuel system requires caution. Before touching any electrical components related to the fuel system, ALWAYS DISCONNECT THE NEGATIVE (-) BATTERY TERMINAL. Use a wrench to loosen the clamp and move the cable away from the battery post. Gasoline vapors are extremely flammable. Sparks can cause fire or explosion. Never smoke or have open flames nearby. Work in a well-ventilated area. Avoid creating sparks. Handle the relay and electrical connectors carefully; forcing them can break terminals or wiring.

DIY Testing: Confirming Relay Failure
While replacing the relay is often inexpensive and simple, confirming it's the culprit before buying parts is wise. Here’s a basic test procedure:

  1. Listen for Pump: With an assistant turning the ignition key to "run" (not crank), listen intently at the rear of the car for the fuel pump priming hum (1-2 seconds). No sound is suspicious.
  2. Access Relay: Follow the steps above to access the relay in the trunk.
  3. Identify & Remove: Locate the relay marked "207". Pull it straight out of its socket. Inspect the socket terminals for corrosion or damage (clean gently with electrical contact cleaner if needed).
  4. Relay Swap (If Possible): Find another identical relay in one of the under-hood fuse/relay boxes (like relay 103, commonly for the radiator fan). Temporarily swap this known-good relay into the fuel pump relay socket.
  5. Key-On Test: With the "borrowed" relay installed, turn the ignition key to "run." Does the fuel pump now hum? If yes, your original relay is faulty.
  6. Listen at Tank: If you couldn't hear the pump initially, you can also try feeling the fuel lines near the engine (use caution!) for pressure after key-on. If pressure builds or the pump hums after the swap, the relay was bad.
  7. Test Port (Advanced): Most 740s have a fuel pump test port near the diagnostic connector in the engine bay (usually a red or black connector). With key "on," carefully jumping terminals 4 (+) and 6 (pump ground) as per the service manual diagram specific to your VIN should activate the pump if the fuse and wiring are good. This bypasses the relay. If the pump runs, the relay circuit is faulty.

Replacement: Step-by-Step
Replacing a confirmed faulty relay is straightforward:

  1. Buy the Correct Part: Obtain a new Bosch "0 332 019 207" relay or a high-quality exact equivalent (Hella, NGK, etc.). Genuine Bosch is recommended. Carry your old relay to the parts store to match the markings and terminal pattern exactly.
  2. Disconnect Battery: ALWAYS disconnect the negative battery terminal first.
  3. Access Relay: Remove the left trunk interior trim panel to expose the relay location.
  4. Remove Old Relay: Simply grasp the old relay firmly and pull it straight out of its socket. Avoid wiggling excessively.
  5. Install New Relay: Align the terminals on the new relay exactly with the pins in the socket. Push it straight down until it seats fully and clips in place. Listen/feel for a click.
  6. Reconnect Battery: Reattach the negative battery cable securely.
  7. Test: Turn the ignition key to "run." You should immediately hear the fuel pump prime for 1-2 seconds. Crank the engine. It should start normally. Replace the trunk trim panel.

Common Misconceptions: Where It's NOT
Due to the trunk location being unusual for many car models, owners often look in the wrong places:

  • Under the Hood: While the engine bay fuse/relay boxes contain important relays (main, fan, A/C, etc.), the primary fuel pump relay for this model year is exclusively in the trunk.
  • Under Dashboard: Fuse panels exist under the dashboard, but these hold fuses only, not the main fuel pump relay.
  • Fuel Tank/Pump Itself: The relay is a separate electrical component mounted remotely, not part of the pump assembly at the tank. You cannot access it by removing the fuel tank cover plate inside the trunk floor.

Beyond the Relay: Other Culprits
If you've confirmed the new relay works and the pump still doesn't run, investigate further:

  • Fuel Pump Fuse: Locate the fuse box under the dashboard near the driver's knees. Check fuse number 6 (typically a 15-amp fuse, verify specific diagram for your car) for the fuel pump. Inspect visually and test with a multimeter for continuity (resistance near zero ohms).
  • Fuel Pump Itself: After confirming fuse and relay are good and power reaches the pump connector (using a multimeter), the pump itself could be faulty. This requires access near/at the fuel tank.
  • Inertia Switch: The 740 has an impact safety switch (inertia switch) near the driver's feet under the kick panel trim. Its purpose is to cut fuel pump power in an accident. Check if it's tripped (a red button pops up) – push it back down to reset it.
  • Wiring Issues: Damaged wires, corroded connectors (especially at the relay socket or pump connector), or broken ground points in the fuel pump circuit can prevent operation. Look for obvious damage and test with a multimeter.
  • ECU or Ignition Signal: The relay needs the correct signal from the ignition system or ECU to activate. While less common than fuse/relay/pump failure, a complete ECU failure or wiring break in this signal path can cause issues. Professional diagnosis is usually needed here.

Maintenance Tips: Proactive Care
Prevention is better than cure:

  • Relay Age: These relays can fail due to age and electrical load cycling. Consider replacing it preventively with a quality Bosch part if the car has very high mileage or the original is still fitted.
  • Clean Connections: Occasionally cleaning the relay socket terminals (when disconnected) with electrical contact cleaner and a small brush can prevent voltage drop issues.
  • Battery Health: Ensure your battery and charging system (alternator) are functioning properly. Low system voltage can stress relays and electrical components.

Finding the fuel pump relay is the critical first step in diagnosing or fixing a sudden no-start caused by fuel pump silence in your 1990 Volvo 740. Remember its unique trunk location on the driver's side behind the trim panel, look for the "207" relay, and always prioritize electrical safety by disconnecting the battery. Understanding its function and common failure symptoms allows for efficient and confident troubleshooting. While other issues can cause similar problems, knowing exactly where to find and test this crucial relay empowers you to get your Volvo back on the road quickly.

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