Possible Causes & Corrections
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Check the following items:
- Ensure vehicle operator is using correct starting procedure.
- Inspect Engine Coolant Temperature (ECT) sensor. Use scan tool to compare ECT with ambient air temperature on a cold engine. If coolant temperature reading is more than 5 degrees more or less than the ambient air temperature on a cold engine, inspect for a high resistance in the coolant sensor circuit or the sensor itself.
- Inspect Fuel Rail Pressure (FRP) sensor. Use scan tool to observe FRP with engine off. FRP reading should be 1.1-1.4 MPa. If not , inspect for high resistance in the low reference, 5-volt reference circuits, or FRP sensor.
- Inspect the Crankshaft Position (CKP) sensor reluctor wheel. Remove the CKP sensor and attempt to move the reluctor wheel front to back or side-to-side with a probe. If there is any movement the reluctor wheel retaining bolts are loose.
- Inspect the fuel pressure regulator 12-volt circuit for an intermittent short to ground. Observe the FRP Command percent while cranking. A range of 85-95 percent indicates a possible short to ground condition.
- Inspect the fuel supply to the fuel injection pump.
- Inspect for a restricted fuel filter.
- Inspect for air in the fuel system.
- Inspect for external fuel leaks.
- Inspect for high engine oil level.
- Inspect fuel return from the fuel injection pump.
- Inspect fuel injectors. Perform Fuel Injector Balance Test using a Tech 2 scan tool.
- Inspect fuel tank cap vent for proper operation.
- Inspect glow plug system for proper operation.
- Inspect for a slow cranking speed.
- Inspect air cleaner and air intake ducts for a restrictions or leaks.
- Inspect for a restriction in turbocharger inlet duct.
- Inspect for a restriction or a leak in the intake manifolds.
- Inspect exhaust system for a possible restriction.
- Improper valve timing.
- Bent push rods.
- Worn rocker arms.
- Low engine compression. See CYLINDER COMPRESSION PRESSURE under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 6.6L SIERRA & SILVERADO - DIESEL article.
- Broken or weak valve springs.
- Worn camshaft lobes.
- Inspect for an intermittent CKP signal.
- Compare scan tool data at idle with scan tool data list. See PID VALUE CHARTS in PID VALUE CHARTS - SILVERADO & SIERRA article.
- Check Service Bulletins for control module software updates.