HARD STARTING OR A NO START CONCERN MAY OCCUR ON SOME VEHICLES. THIS MAY BE DUE TO DIESEL FUEL DRAINING OUT OF THE FUEL INJECTION SYSTEM BACK INTO THE FUEL TANK. THIS CONDITION CAUSES THE INJECTION SYSTEM TO LOSE ITS PRIME WHICH LEADS TO LONGER STARTER ENGAGEMENT TIMES FOR ENGINE SHUTDOWN PERIOD. INSTALL A DIESEL FUEL CHECK VALVE (F5HZ-9285-AA) ON THE FUEL RETURN LINE AT THE REAR OF THE ENGINE.