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DIAGNOSIS OF TROUBLE.

A. Engine stops unexpectedly while driving.

  1. What were the immediately preceding symptoms?

    2. (a) Did the power fall off smoothly. with an occasional popping in the carburettor? If so, the cause is probably in the petrol system.

    (b) Did the engine stop suddenly, possibly with, a very brief period of irregular running? If so the cause is probably in the ignition system.

B. Testing the Petrol System.

  1. Does the carburettor flood on lifting the needle valve A?

    2. No. The fault lies between the carburettor float chamber and the tank.

    Yes. The fault lies between the float chamber and the cylinder.

C. Testing Petrol Supply between Carburettor Float Chamber and Tank.

  1. Does the petrol flow on opening the autovac drain cock B? (Turn handle to horizontal position.)

    2. (a) Yes. The fault is between the autovac and float chamber.

    (i) Is the cock C open? (Handle vertically downwards,)

    (a) Yes. The fault lies in the pipe D to the carburettor. Close cock C and disconnect pipe D by unscrewing unions at each end, and blow through the pipe to clear it.

    (b) No. The fault is either in:-

    (i) The petrol supply from the tank to autovac or

    (ii) The suction system from induction pipe to autovac