13. FUEL INJECTION SYSTEM Downtown 300i ABS TROUBLESHOOTING Engine fail to start Backfiring or misfiring during acceleration · Intake manifold air leak · Ignition system malfunction · Fuel contaminated/deteriorated · Pinched or clogged fuel hose · Faulty fuel pump · Clogged fuel filter, throttle body · Sticking fuel injector needle · Faulty fuel pump operating system · Carbon deposit stayed on the fuel injector · Spark plug dirty · Fuel pressure incorrect Engine stall, hard to start, rough idling Poor performance (drive ability) and poor · Intake air leak fuel economy · Fuel contaminated/deteriorated · Pinched or clogged fuel hose · Pinched or clogged fuel hose · Faulty injector · Idle speed fail to adjust · Fail to perform PTS/ISC reset 13-6