14. DOWNTOWN 125 i FUEL SYSTEM (Auto Control Fuel Injection System) 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 · Clogged fuel filter (fuel pump) · Pinched or clogged fuel hose · Clogged fuel injector · Faulty fuel injector · Faulty spark plug or wrong type · Cut by ECU due to angle detect sensor or incorrect function Engine stall, hard to start, rough idling · Intake air leak · Fuel contaminated/deteriorated · Pinched or clogged fuel hose · Idle speed misadjusted 14-4