Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Procedures
2004 Oldsmobile Bravada RWDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
- Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L SONOMA & S10 PICKUP article. After performing diagnostic system check, go to next step.
- Turn ignition on, with engine off. Using scan tool, command fuel pump relay on. Does fuel pump operate? If yes, go to next step. If no, diagnose fuel pump electrical circuit. Refer to FUEL PUMP ELECTRICAL CIRCUIT TEST under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 2.2L SONOMA & S10 PICKUP article.
- Turn ignition off. Turn A/C system off. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Install Fuel Pressure Gauge (J-34730-FF). Turn ignition on, with engine off. Command fuel pump relay ON with scan tool. Observe fuel pressure gauge with fuel pump commanded ON. Is fuel pressure 55-62 psi (379-427 kPa)? If yes, go to next step. If no, go to step 9 .
- Fuel pressure may vary slightly when fuel pump stops. After fuel pump stops, fuel pressure should stabilize and remain constant. Note fuel pressure when fuel pump stops running. If fuel pressure decreases more than 5 psi (34 kPa) in one minute, go to step 7 . If fuel pressure does not decrease more than 5 psi (34 kPa) in one minute, go to next step.
- Relieve fuel pressure to 10 psi (69 kPa). Monitor fuel pressure gauge for 5 minutes. Does fuel pressure decrease by more than 2 psi (14 kPa)? If yes, go to step 17 . If no, go to next step.
- Operate the vehicle within the conditions to reproduce the original symptoms. Monitor O2 and fuel trim parameters with a scan tool. Do the scan tool parameters indicate a lean condition? If yes, go to step 12 . If no, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L SONOMA & S10 PICKUP article.
- Turn ignition off. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Disconnect fuel feed hose from fuel rail. Install Fuel Line Shut-Off Adapter (J-37287) between fuel hose and fuel rail. Open valve on fuel pipe shut-off adapter. Turn ignition on, with engine off. Command fuel pump relay ON with scan tool. Bleed air from fuel pressure gauge. Command fuel pump relay ON and then OFF with scan tool. Close fuel feed pipe shut-off valve. Monitor fuel pressure gauge for one minute. Does the fuel pressure remain constant? If yes, go to next step. If no, go to step 15 .
- Turn ignition off. Open fuel feed pipe shut-off valve. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Raise and support vehicle. Disconnect fuel return pipe from fuel filter. Install Fuel Line Shut-Off Adapter (J-37287) between fuel return pipe and fuel filter. Open fuel return pipe shut-off valve. Turn ignition on, with engine off. Command fuel pump relay ON with scan tool. Bleed air from fuel pressure gauge. Command fuel pump relay ON and then OFF with a scan tool. Close the fuel return pipe shut-off valve. Monitor the fuel pressure gauge for one minute. Does fuel pressure remain constant? If yes, go to step 16 . If no, go to step 17 .
- Is the fuel pressure greater than 62 psi (427 kPa)? If yes, go to step 11 . If no, go to next step.
- Turn ignition off. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Raise and support vehicle. Disconnect fuel return pipe from fuel filter. Install Fuel Line Shut-Off Adapter (J-37287) between fuel return pipe and fuel filter. Open the valve in the fuel pipe shut-off adapter. Turn ignition on, with engine off. Bleed air from the fuel pressure gauge. Monitor fuel pressure gauge. DO NOT allow fuel pressure to exceed 75 psi (517 kPa). Excessive pressure may damage fuel system. Command fuel pump relay ON with a scan tool. Slowly close the valve in the fuel return pipe shut-off adapter, while the fuel pump is operating. Does the fuel pressure increase to greater than 62 psi (427 kPa)? If yes, go to step 16 . If no, go to step 12 .
- Inspect fuel return pipe for a restriction. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 16 .
- Inspect for a restricted fuel filter or fuel feed pipe. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
- Inspect the harness connectors and the ground circuits of the fuel pump for poor connections. Did you find and correct the condition? If yes, go to step 18 . If no, go to next step.
- Remove fuel sender assembly. Inspect fuel pump flex hose for damage, in-tank fuel pump harness connectors for poor connections, fuel strainer for a restriction or fuel tank for contaminants. Did you find and correct the condition? If yes, go to step 18 . If no, go to step 17 .
- Turn ignition off. Raise fuel rail assembly with fuel pipe connected. Turn ignition on, with engine off. Command fuel pump relay ON with scan tool. Locate and replace leaking fuel injector. After repairs, go to step 18 .
- Replace fuel filter. After replacing fuel filter, go to step 18 .
- Replace fuel sender. After replacing fuel sender, go to next step.
- Operate the system in order to verify the repair. Did you correct the condition? If yes, system is okay. If no, go to step 3 .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.