Symptom Checks

Perform the following:

Check if engine will start with throttle closed. If engine starts, go to CIRCUIT TEST Z in appropriate article and check for intermittent causes of no-start condition:

For 4.2L Pickup, see TESTS W/CODES - 4.2L .

For 4.6L Pickup, see TESTS W/CODES - 4.6L .

Check if engine will start at part throttle. If engine starts, Idle Air Control (IAC) system may be defective. Go to CIRCUIT TEST KE, step 2) in appropriate TESTS W/CODES article.
Check ignition and fuel system. See CIRCUIT TEST A in appropriate article:

For 4.2L Pickup, see TESTS W/CODES - 4.2L .

For 4.6L Pickup, see TESTS W/CODES - 4.6L .

Check for restricted exhaust system. See CIRCUIT TEST HF in appropriate TESTS W/CODES article.
Check engine mechanical condition. Check compression, camshaft, valve train components, etc. If no problems are indicated, return to SYMPTOM DIAGNOSIS to identify any additional symptoms or go to CIRCUIT TEST Z in appropriate article and check for intermittent faults:

For 4.2L Pickup, see TESTS W/CODES - 4.2L .

For 4.6L Pickup, see TESTS W/CODES - 4.6L .