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8. FUEL INJECTOR OPERATION WARNING: The fuel system is under a constant pressure (even with the engine off). Before testing or ser- CAUTION: After each Fuel Injector actuation, start the engine to clean the cylinder of fuel. Failure to do so Start the engine and allow the fuel pressure to reach maximum pressure. Ignition on, engine not running. Using the scan tool, actuate the Fuel Injector for the cylinder that indicated the misfire. Monitor the fuel pressure gauge. Does the fuel pressure gauge indicate a drop in fuel pressure? Yes >> Go To 9 No >> Go To 10 NOTE: Turn the ignition off, remove the Fuel Pressure gauge, and connect the fuel lines before continuing. 9. ENGINE MECHANICAL PROBLEM Check for any of the following conditions/mechanical problems. ENGINE VACUUM - must be at least 13 inches in neutral ENGINE VALVE TIMING - must be within specifications ENGINE COMPRESSION - must be within specifications ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks. ENGINE PCV SYSTEM - must flow freely TORQUE CONVERTER STALL SPEED - must be within specifications POWER BRAKE BOOSTER - no internal vacuum leaks FUEL - must be free of contamination CAM LOBES - must not be worn excessively CYLINDER LEAKAGE TEST - must be within specifications VALVE SPRINGS - cannot be weak or broken Are there any engine mechanical problems? Yes >> Repair as necessary. Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) No >> Go To 17 10. FUEL INJECTOR Turn the ignition off. Disconnect the Fuel Injector harness connector of the misfiring cylinder. Ignition on, engine not running. NOTE: When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinders Injector Using a 12-volt test light connected to 12-volts, probe the Injector Control circuit. With the scan tool, actuate the Fuel Injector. Does the test light blink/flicker? Yes >> Replace the Fuel Injector. Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE) No >> Go To 11 9 - 234 ENGINE ELECTRICAL DIAGNOSTICS KJ |