1. Electrical Problems:
* Blown Fuse: Check the fuse box for a blown fuse related to the fuel pump. The specific fuse may be labeled, or you may need to consult your owner's manual.
* Relay Failure: The fuel pump is usually controlled by a relay. A faulty relay will prevent power from reaching the pump. Testing the relay with a multimeter is necessary.
* Wiring Issues: Look for broken, corroded, or loose wires in the wiring harness leading to the fuel pump. This includes checking the connections at the pump itself. Rodents can sometimes chew on wiring harnesses.
* Inertia Switch: Some cars have an inertia switch that cuts power to the fuel pump in a collision. Check if this switch has tripped (usually located under the dash or in the engine compartment). Resetting it might resolve the issue.
* Ignition Switch Problem: A malfunctioning ignition switch can prevent power from reaching the fuel pump circuit.
* Computer (ECM) Issues: In some cases, a faulty engine control module (ECM) could be responsible, though this is less likely to be the primary cause unless there are other engine problems.
2. Fuel Pump Problems:
* Pump Failure: The fuel pump itself could have failed. This is a common point of failure as they are mechanical devices subject to wear and tear.
* Pump Wiring/Connector: Even with power reaching the harness, a problem in the connector at the pump or the pump itself could prevent it from working.
3. Other Potential Problems:
* Fuel Pump Relay Circuit: This involves tracing the relay’s power and ground circuits to ensure there are no shorts or open circuits that are preventing it from operating.
* Low Fuel Level: While unlikely to completely cut power, an extremely low fuel level might trigger a sensor that temporarily disables the pump (check your fuel gauge).
Troubleshooting Steps:
1. Start with the easiest: Check the fuel pump fuse first. This is the quickest and cheapest check.
2. Check the inertia switch: Reset it if it's tripped.
3. Listen for the fuel pump: When you turn the ignition key to the "on" position (without starting the engine), you should hear a brief humming sound from the fuel pump. If you don't hear it, this points to an electrical problem or a pump failure.
4. Use a multimeter: Test the voltage at the fuel pump connector. You should have battery voltage when the ignition is on. If you don't, trace back the wiring to find the break in the circuit.
5. Check the relay: Test it with a multimeter or swap it with a known good relay of the same type.
6. Inspect the wiring: Look for any signs of damage, corrosion, or loose connections in the wiring harness running to the fuel pump.
7. Check the fuel level: Rule out a completely empty tank.
If you're not comfortable working with car electrical systems, it's best to take your Sunbird to a qualified mechanic. Improperly diagnosing and repairing electrical issues can be dangerous.
