22. FUEL INJECTION SYSTEM MXU 500i TROUBLESHOOTING Engine won't start Backfiring or misfiring during acceleration · Battery voltage too low · Ignition system malfunction · Fuel level too low · Pinched or clogged fuel hose Poor performance (drive ability) and poor · Faulty fuel pump operating system fuel economy · Pinched or clogged fuel hose · Clogged fuel injector · Faulty fuel injector · Faulty spark plug or wrong type · Clogged Airflow Bypass Valve · Wet spark plug Engine stall, hard to start, rough idling · Intake air leak · Fuel contaminated/deteriorated · Pinched or clogged fuel hose · Idle speed miss adjusted · Wet spark plug 22-8