Here's a breakdown of how to check your fuel pump:
1. Listen for the Fuel Pump:
* Key On, Engine Off (KOEO): Turn the ignition key to the "ON" position (don't start the engine). You should hear a brief humming sound from the fuel pump in the fuel tank. This usually lasts for a few seconds. This confirms the pump is receiving power and is trying to prime the system. If you don't hear this, it could indicate a faulty pump, a blown fuse, or a problem with the fuel pump relay.
2. Check the Fuel Pump Relay:
* Locate the Relay: Consult your owner's manual to find the location of the fuel pump relay in your fuse box (usually under the hood or inside the car). The relay itself might be labeled, or you can compare the relay with the diagram in your owner's manual.
* Visual Inspection: Examine the relay for any signs of damage, such as burning or corrosion.
* Relay Swap (if possible): If you have another relay of the same amperage and type, try swapping it with the fuel pump relay. This helps determine if the relay itself is the problem. If the problem goes away after the swap, you've found your culprit.
3. Check the Fuel Pump Fuse:
* Locate the Fuse: Your owner's manual will show the location and amperage of the fuel pump fuse.
* Visual Inspection: Check for a blown fuse (a broken filament is usually visible). Replace it if necessary with a fuse of the same amperage.
4. Check Fuel Pressure (Most Difficult):
This requires a fuel pressure gauge and involves some specialized knowledge. Proceed with extreme caution. Gasoline is extremely flammable.
* Obtain a Fuel Pressure Gauge: You'll need a fuel pressure gauge designed for automotive use.
* Connect the Gauge: The connection point for the fuel pressure gauge varies depending on the specific year and model. Consult a repair manual for your vehicle to find the correct location and procedure.
* Check Pressure: Turn the key to the "ON" position. The gauge should show the fuel system pressure (your vehicle's specifications should indicate the proper pressure range). Low or no pressure indicates a potential fuel pump issue.
5. Inspect the Fuel Pump Wiring:
* Access the Fuel Pump (Advanced): Accessing the fuel pump requires dropping the fuel tank – a significantly more complex procedure requiring specialized tools and potentially a lift or jack stands. Unless you are comfortable with automotive repair and have the necessary tools and safety equipment, this should be done by a qualified mechanic.
* Check Wiring for Damage: Inspect the wiring harness leading to the fuel pump for any signs of damage, such as frayed wires, corrosion, or broken connections.
Important Considerations:
* Repair Manual: A repair manual specific to your 1997 Pontiac Sunfire is highly recommended. It will provide detailed diagrams and procedures for accessing and testing the fuel pump and related components.
* Professional Help: If you're not comfortable performing these checks yourself, take your Sunfire to a qualified mechanic. Working on the fuel system is potentially dangerous if not done correctly.
By systematically checking these components, you should be able to narrow down the cause of your fuel pump problem. Remember safety first! If you are unsure about any step, seek professional help.
