1. Check the Basics:
* Power: The most common cause. The fuel pump needs power to run. This involves checking:
* Fuse: Locate the fuel pump fuse in your fuse box (usually under the hood or in the interior). Check for a blown fuse and replace it if necessary. Your owner's manual will show you the fuse box diagram.
* Relay: Many '89 Chevy trucks use a fuel pump relay. This is a small electrical switch that activates the pump. Locate the relay (often near the fuse box) and try swapping it with a known good relay of the same amperage (again, consult your owner's manual). You can usually hear the relay click when it's working properly.
* Wiring: Inspect the wiring harness leading to the fuel pump for any damage, corrosion, or loose connections. Pay close attention to the area where the wiring enters and exits the fuel tank.
* Inertia Switch: Some vehicles have an inertia switch that cuts power to the fuel pump in case of a collision. This is usually a small, red button located under the dash or in the engine compartment. Press it to reset it if it's tripped.
* Fuel Pump Inhibitor Switch: Some vehicles, especially those with manual transmissions, have a clutch safety switch (or similar) that prevents the fuel pump from operating unless the clutch is depressed. If you have a manual transmission, check if this switch is functioning correctly.
2. Testing the Fuel Pump (requires some mechanical skill):
* Listen for the pump: With the key in the "ON" position (don't crank the engine), have someone listen near the fuel tank. You *should* hear a brief hum or whirring sound from the pump as it primes. If you don't hear anything, this points to a power or pump problem.
* Direct Power Test (Use CAUTION!): This is potentially dangerous. Disconnect the negative battery terminal before starting. This test requires you to directly apply power to the fuel pump wiring. You'll need a test light or a multimeter to apply 12V to the pump wires (while maintaining the negative terminal connection). Only do this if you have experience with automotive electrical systems. If the pump runs with direct power, then the problem is likely with the fuse, relay, or wiring. If it still doesn't run, the pump itself may be faulty.
3. Further Diagnosis:
If the above steps don't solve the issue, you'll likely need further diagnostics:
* Professional mechanic: This is recommended if you're uncomfortable working with automotive electrical systems or fuel systems. They have the tools and expertise to pinpoint the problem more accurately.
* Fuel pressure test: A mechanic can perform a fuel pressure test to check if the fuel pump is delivering the correct pressure. Low pressure indicates a pump or related component problem.
* Fuel pump replacement: If the pump itself is faulty, it will need to be replaced. This is a more involved repair that typically requires dropping the fuel tank.
Safety Precautions:
* Gasoline is highly flammable. Work in a well-ventilated area, away from open flames and sparks.
* Disconnect the negative battery terminal before working on any electrical components.
* Use caution when working near the fuel tank.
* Consult your vehicle's repair manual for specific instructions and diagrams.
Remember, working on fuel systems can be dangerous. If you're unsure about any step, seek professional help. A faulty fuel pump can leave you stranded, so addressing this issue promptly is important.
