Possible Cause & Correction
- Check the following items:
- Check fuel pump relay. To do this, connect test light between fuel pump test terminal (terminal "G" of ALDL on most vehicles) and ground. Turn ignition on. Light should illuminate for 2 seconds. If not, see FUEL PUMP RELAY in the article SYSTEM/COMPONENT TESTS . For location of fuel pump test connector, see COMPONENT LOCATIONS in the article I - SYSTEM/COMPONENT LOCATIONS .
- Check for poor quality or water contaminated fuel.
- Check that TPS is not sticking or binding.
- Check EGR operation.
- Check for a leaking injector. To do this on TBI systems, disconnect injector electrical connector at injector. Crank engine and watch for fuel leakage.
- Check that resistance of coolant sensor circuit or coolant sensor is not too high. See CODE 15 chart in appropriate TESTS W/CODES article, or the SENSOR RANGE CHARTS article.
- Check ignition system for a worn distributor shaft, bare or shorted wires, incorrect pick-up coil resistance, loose ignition coil ground or moisture in distributor cap. Check for adequate spark using Spark Tester (ST-125).
- Check for shorts by spraying plug wires with fine mist of water.
- Remove spark plugs and check for wet plugs, cracks, improper gap, burned electrodes or heavy carbon deposits.
- Check for correct fuel pressure in all speed ranges.
- A faulty in-tank fuel pump check valve will allow fuel in lines to drain back to tank after engine is stopped. To check this condition, turn ignition off, disconnect fuel pressure line at fuel rail, remove filler cap, and connect a radiator test pump and apply 15 psi (1.0 kg/cm2 ) pressure. If pressure will hold for 60 seconds, check valve is okay.
- Check that PROM/MEM-CAL in vehicle is correct for that vehicle. See ECM/PROM under ENGINE PERFORMANCE for latest application information.
- Check for restricted exhaust system.