1. Verify the New Fuel Pump Installation:
* Properly grounded? A poorly grounded fuel pump won't work. Double-check all grounding connections.
* Correct pump? Ensure you installed the *correct* fuel pump for your specific engine and model year. A wrong pump can cause problems.
* Wiring harness: Inspect the wiring harness to the fuel pump for any damage, corrosion, or loose connections. Pay close attention to the power and ground wires.
2. Check for Fuel Pressure:
This is crucial. You need a fuel pressure gauge to test the pressure at the fuel rail (where the injectors are). The correct pressure should be specified in your owner's manual or a repair manual for your specific engine. Low or no pressure indicates a problem beyond the pump.
3. Other Potential Problems (if fuel pressure is low or absent):
* Fuel Filter: A clogged fuel filter is a common cause of low fuel pressure. Replace it. It's cheap and easy to do.
* Fuel Pump Relay: A faulty relay can prevent power from reaching the pump. Swap the relay with a known good one (another relay of the same amperage rating – usually found in the underhood fuse box).
* Clogged Fuel Lines: Rare, but possible. Check the lines for kinks or blockages, especially the line between the tank and the filter.
* Fuel Tank Sender Unit: This unit measures the fuel level and can sometimes interfere with fuel flow if faulty. Replacing this is more involved.
* Fuel Pressure Regulator: This regulator maintains fuel pressure in the fuel rail. A faulty one could cause low or no pressure.
* In-Tank Fuel Pump Module: If you only replaced the pump itself and not the entire module assembly, there could be other components within the module that are faulty.
* Wiring issues at the pump: A break in the wire itself could be happening near the pump.
4. Check the Injectors (if you have fuel pressure):
If you *do* have fuel pressure, the problem might be with the fuel injectors themselves. They could be clogged or electrically faulty. This requires specialized tools and testing.
5. Start Simple, Eliminate Possibilities:
* Start with the easiest and cheapest fixes first: Fuel filter, relay swap.
* Use a fuel pressure gauge: This is the most important diagnostic tool in this situation.
* Consult a Repair Manual: A Haynes or Chilton manual for your Silverado will provide detailed diagrams and troubleshooting steps.
If you're not comfortable performing these checks yourself, take it to a qualified mechanic. Improperly working with fuel systems can be dangerous. Incorrectly diagnosing the problem could lead to further damage or even fire.
