mxu 50 Manuel atelier : Page 34

          1. GENERAL INFORMATION                                                                         ATV 50


 ENGINE STOPS IMMEDIATELY AFTER IT STARTS

 Inspection/Adjustment                        Symptom                     Probable Cause

 Check if fuel reaches
 carburetor by loosening
 drain screw.
                                                                          Empty fuel tank
                                 Fuel reaches       Fuel does not         Clogged float valve
                                 carburetor         reach carburetor      Clogged charcoal canister
                                                                          Clogged fuel filter
                                                                          Faulty auto fuel valve
 Remove spark plug and
 install it into spark plug
 cap to test spark by
 connecting it to engine
 ground.
                              Plug not fouled or    Plug fouled or        Fouled spark plug
                              discolored            discolored            Incorrect heat range plug
 Remove spark plug and
 install it into spark plug
 cap to test spark by
 connecting it to engine                                                  Fouled spark plug
 ground.                                                                  Faulty CDI unit
                                                     Weak or inter-       Faulty A.C. generator
                                 Good spark          mittent spark        Faulty ignition coil
                                                                          Broken or shorted high
                                                                          tension wire
 Test cylinder                                                            Faulty ignition switch
 compression (using a
 compression gauge).
                                                                          Worn cylinder and piston
                                                                          rings
                                 Normal                 Abnormal          Blown cylinder head gasket
                                 compression            compression       Flaws in cylinder head
                                                                          Faulty reed valve
                                                                          Seized piston
 Check carburetor for
 clogging.


                                 Not Clogged             Clogged          Clogged carburetor jets


 Check ignition timing.

                                                                          Faulty CDI unit or A.C.
                                Correct timing      Incorrect timing      generator
                                                                          A.C.G. flywheel not aligned

 Check carburetor air
 screw adjustment.

                                                                          Mixture too rich (turn screw
                              Correctly adjusted   Incorrectly adjusted   out)
                                                                          Mixture too lean (turn screw
                                                                          in)


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