The 2003 Chevy avalanche came standard with a 5.3-liter eight-cylinder engine and a four-speed automatic transmission. The fuel pump on your Avalanche is located inside the fuel tank and may be the cause of sluggish performance or a non-starting engine. The fuel systems consists of the fuel pump and strainer, fuel lines, fuel filter, fuel pressure regulator, fuel rail and fuel injectors. To test the fuel pump correctly and efficiently diagnose the fuel pump, there are a few specialty tools needed, but they generally are available to rent at parts stores.
Instructions
- 1
Park the vehicle on a level surface and set the parking brake. Turn the ignition to the Off position. Lift the hood and support it with the hood prop rod. Remove the bolt securing the plastic cover to the top of the engine with the socket and ratchet.
2Locate the fuel rail that is over the intake manifold and find the Schrader valve; it has a black cap. Remove the cap to expose the valve. Wrap a shop rag around the valve and slowly depress the valve with a screwdriver to relieve fuel pressure.
3Install the fuel pressure gauge onto the Schrader valve and turn the gauge valve to the closed position. Squeeze the tabs for the quick disconnect fitting on the fuel return line, and separate the return line from the fuel rail. Install the fuel shut-off insert between the fuel rail and return line by clicking them into place.
4Install the scan tool to the OBD-II port below the driver side dashboard. Turn on the scan tool and allow it to communicate with the vehicle computer. If necessary, enter requested information such as make, model and year. Attach the 3/8-inch rubber hose to the opposite end of the fuel pressure gauge.
5Enter "diagnostics" mode on the scan tool, then select "fuel system." Direct the rubber hose from the pressure gauge to the small gas can. Turn the shut-off insert valve to the open position. Enable the fuel pump and slowly open the pressure gauge valve to bleed any air from the fuel system. Close the valve when there no longer is any air or hissing noise coming from the rubber hose. The diagnostic scan tool should have turned off the fuel pump; if not, select the option on the scan tool to turn off the fuel pump.
6Watch the fuel pressure gauge and turn the fuel pump on with the scan tool. Proper fuel pressure is 62 psi for gasoline and 54 psi for E85 engines. If the fuel pressure does not rise to or above the required psi, inspect the fuel sending lines for any leaks and replace the fuel filter, then proceed to the next step. If the fuel pressure exceeded the pressure requirements and the engine still is sluggish or does not start, inspect and replace the fuel pressure regulator and test drive the vehicle.
7Again check the fuel pressure after replacing the fuel filter and any damaged fuel lines. If the pressure still does not meet the required psi, visually inspect the fuel pump wire harness connector for damage or corrosion, and inspect the ground wire that travels from the fuel pump to the frame rail. Replace any damaged wire or harness. Check the fuel pressure after repairing any wiring damage; if there are no damaged wires or the pressure doesnt meet the required psi, replace the fuel pump and fuel strainer.
8Remove the scan tool from the vehicle and turn the ignition key to the Off position. Open the valve on the pressure gauge to relieve the fuel pressure. Disconnect the fuel pressure gauge and install the Schrader valve cap.
9Squeeze the tabs for the fuel shut-off insert quick connect fittings and remove the insert from between the fuel rail and return line. Connect the return line to the fuel rail by clipping the line into the fitting on the fuel rail. Install the plastic engine cover and tighten the retaining nut snug with the socket and ratchet. Shut the vehicle hood and test drive the vehicle to ensure the engine is running smoothly.
