Possible Cause & Correction

Check the following items:

• Check fuel pump relay by connecting test light between fuel pump relay connector ignition feed circuit and ground. Turn ignition on. Light should illuminate for 2 seconds. If light does not illuminate for 2 seconds, see RELAYS under MODULES, RELAYS & SOLENOIDS in appropriate SYSTEM & COMPONENT TESTING article. For location of fuel pump test connector, see COMPONENT LOCATIONS in appropriate SYSTEM & COMPONENT TESTING article.
• Check for open injector fuse(s).
• Check for poor quality or alcohol contaminated fuel.
• Check for binding or sticking TP sensor, or high TP sensor voltage with throttle closed.
• Check EGR operation.
• Check for leaking fuel injector.
• Ensure resistance of Engine Coolant Temperature (ECT) sensor circuit is within specification. See appropriate SENSOR OPERATING RANGE CHARTS article.
• Check resistance of ECT and Intake Air Temperature (IAT) sensors. On a cold engine, ECT and IAT sensor readings should be within 5°F of each other.
• Check for proper spark output using Spark Tester (J-26792).
• Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits.
• Check fuel pressure. See FUEL SYSTEM PRESSURE TEST under BASIC FUEL SYSTEM CHECKS in appropriate BASIC DIAGNOSTIC PROCEDURES article.
• Check for plugged injectors. Perform injector balance test. See FUEL INJECTOR BALANCE TEST under FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article.
• Check for loose ignition coil ground and power feed circuit connections. Also check ignition coil fuse.
• Check for faulty in-tank fuel pump check valve (if equipped). A faulty in-tank fuel pump check valve will allow fuel to drain back to tank after engine is stopped. To check this condition, turn ignition off, disconnect fuel pressure line at fuel rail and remove filler cap. Using a radiator pressure tester, apply 15 psi (1.0 kg/cm² ). If pressure holds for 60 seconds, check valve is okay.
• Ensure the installed PCM program is correct for the particular vehicle. Check with dealer for latest application information.
• Check for restricted exhaust system, such as a damaged or collapsed pipe, muffler or catalytic converter.
• Check Idle Air Control (IAC) system. Check for vacuum leak at high idle. Check for binding of throttle blade or linkage. Check for foreign material in IAC bore of throttle body. Check for proper connection of IAC valve electrical connector. Check for failure of A/C compressor or relay.
• Check Manifold Absolute Pressure (MAP) and/or Mass Airflow (MAF) sensor. Check air intake tube for air leaks, blockage or damage.
• Inspect Crankshaft Position (CKP) sensor clearance and resistance. Check harmonic balancer interrupter rings for bent or missing vanes.
• Check if PCV valve is stuck open.
• Using a scan tool, check the Idle Air Control (IAC) operation.
• Check basic engine mechanical problems (i.e., compression, head gasket(s), valves). Check for incorrect valve timing, bent push rods, broken valve springs or worn camshaft lobes.
• Check PCM and engine grounds for correct locations, tight and clean connections. See WIRING DIAGRAMS article.