1. Listen for the Fuel Pump Prime:
* Turn the ignition key to the "ON" position (without starting the engine). You should hear a whirring sound for a few seconds from the fuel tank area. This is the fuel pump priming the system. If you don't hear it, the pump might be faulty, or there could be a problem with the pump relay or fuse.
2. Check the Fuel Pressure:
* This requires a fuel pressure gauge. You'll need to connect the gauge to the fuel system's test port (location varies depending on the engine; consult your repair manual). The pressure should be within the specifications listed in your owner's manual or a repair manual specific to your Tahoe's engine. Low or no pressure indicates a fuel pump problem, but could also point to other issues (fuel filter, pressure regulator, etc.).
3. Inspect the Fuel Pump Relay and Fuse:
* Locate the fuel pump relay and fuse in your Tahoe's fuse box (usually under the hood or inside the cabin). Check the fuse for a blown element (a broken wire inside). If it's blown, replace it with one of the same amperage rating. If the fuse blows immediately after replacement, there's a short circuit somewhere in the system. If the fuse is okay, check the relay by visually inspecting it for damage, or swap it with another relay of the same type (if possible). This helps to isolate whether the problem is with the relay itself or another part of the system.
4. Check for Power at the Fuel Pump:
* This requires a multimeter. You'll need to access the fuel pump wiring connector (usually located near the fuel tank). With the ignition ON, check for voltage at the connector. If there's no voltage, the problem could be a faulty wiring harness, relay, or even a computer problem. This step requires some electrical knowledge and careful attention to safety.
5. Observe the Engine's Performance:
* If the engine cranks but won't start or sputters and dies, a faulty fuel pump is a strong possibility. However, this symptom could be caused by many other issues, so it's not definitive proof.
6. Smell for Fuel:
* If you smell fuel, it could indicate a leak. While not directly related to pump function, a leak could be caused by a faulty pump.
Important Considerations:
* Repair manuals: Consult a repair manual specific to your 1999 Chevy Tahoe. These manuals provide detailed diagrams, specifications, and troubleshooting procedures.
* Professional help: If you're not comfortable performing these checks, take your Tahoe to a qualified mechanic. Working with fuel systems requires caution and proper tools.
If you've checked these points and still suspect a faulty fuel pump, replacing it will likely require dropping the fuel tank, which is a more involved repair job best left to someone with experience.
