1. Verify Fuse Integrity (Again, More Thoroughly):
* Visual Inspection Isn't Enough: Even if a fuse looks fine, it might be blown. Use a multimeter to test continuity across the fuse terminals. A blown fuse will show infinite resistance (open circuit).
* Check All Relevant Fuses: There might be multiple fuses related to the fuel pump circuit. Consult your owner's manual to find all potentially relevant fuses and relays (fuel pump relay is a common culprit). Test *each one* individually with the multimeter.
2. Fuel Pump Relay:
* Location: Find the fuel pump relay in your underhood fuse box or a separate relay center (location varies by year and trim). The owner's manual is crucial here.
* Testing: A multimeter is necessary. You'll need to test for power at the relay's input and check if the relay is switching properly when the ignition is turned on. There are many online guides and videos specific to 1999 Silverado fuel pump relay testing – search for "1999 Silverado fuel pump relay test" on YouTube.
* Swap the Relay (if possible): If you have a spare relay, try swapping it with a known good one (of the same type) to rule out a faulty relay.
3. Wiring Harness Inspection:
* Visual Inspection: Carefully examine the wiring harness leading from the fuse/relay to the fuel pump. Look for any signs of damage, chafing, corrosion, or broken wires. Pay close attention to areas near the tank where wires are subject to movement and abrasion.
* Continuity Testing: Use a multimeter to check continuity between the fuse/relay and the fuel pump connector. Disconnect the fuel pump connector before testing. If you have no continuity, you have a break in the wiring somewhere along the line. Tracing this requires patience and potentially probing the wiring along its path.
* Ground Connection: A poor ground connection can prevent the fuel pump from receiving power. Locate the ground wire for the fuel pump and ensure it's clean and securely connected.
4. Inertia Switch:
* Location: Some vehicles have an inertia switch that cuts power to the fuel pump in the event of a collision. Locate this switch (usually under the dash or in the engine compartment – check your manual) and check if it's tripped. Reset it if it is.
5. Fuel Pump Wiring Connector:
* Check the connector: Examine the connector at both the fuel pump and the harness for corrosion or damage. Clean any corrosion and ensure a secure connection.
6. Fuel Pump (Least Likely, But Possible):
* It's Possible (but Less Likely): It's conceivable that the fuel pump itself is malfunctioning, even if it's not getting power. However, you should troubleshoot the power delivery issues first.
Important Safety Precautions:
* Disconnect the battery's negative terminal before working on the electrical system.
* Be careful when working near fuel lines and the fuel tank. Avoid sparks and open flames.
* Use appropriate safety glasses and gloves.
If you're not comfortable performing these tests yourself, it's best to take your truck to a qualified mechanic. They have the tools and expertise to diagnose and repair the problem efficiently and safely. Remember, the detailed wiring diagrams in your owner's manual (or a reputable online repair manual) will be invaluable throughout this process.
