h. Difficult Starting, Fuel Mixture Too Rich. Air cleaner oil cup overfilled, or cleaner elements exceptionally dirty, choking off adequate air supply to carburetor. Check the oil cup level. If oil cup level is correct, remove, clean, and install cleaner elements (par. [76]).
32. IGNITION SYSTEM.
a. When checking ignition system for trouble, make the most obvious and simple checks first. For example: Turn on ignition and light switch, observe lights to ascertain battery current supply; then check to see that current is reaching spark coil, circuit breaker, etc. Faulty spark plugs are responsible for the great majority of engine ignition troubles. There is no service for spark plugs other than sandblast cleaning and correct adjustment of electrodes. Questionable spark plugs must be replaced (par. [83]).
b. Remedy all poor connections in ignition wiring system ( [fig. 48]).
c. Remove circuit breaker cover, operate engine with starter pedal, and observe opening and closing of circuit breaker points. Correct point gap when breaker lever fiber is on highest point of cam is 0.022 inch. For adjustment refer to paragraph [84].
d. Testing for High Tension Spark. Spark at plug gaps depends upon condition and operation of circuit breaker points, condition of condenser, and condition of spark coil and high‐tension cables. Testing the ignition system is best done by means of elimination, testing each unit by replacement until trouble is located; then replacing serviceable units which were removed.
(1) Remove spark plug cable terminal from either plug, leaving other cable and plug connected (to effect ground return of high‐tension current); turn engine until circuit breaker points are closed; turn ignition and light switch on; hold high tension cable terminal ¼ inch from cylinder; open and close circuit breaker points with finger and observe spark jump at gap. If spark jumps gap, it indicates ignition primary and secondary circuits are complete.
(2) No spark at high‐tension gap calls for testing of primary and secondary circuits. Turn engine until breaker points are held open; hold cable end ¼ inch from cylinder; turn ignition switch on and with the bit of a screwdriver, make a good ground connection between breaker movable (lever) point, and the ground. If a good spark is obtained at high‐tension cable terminal gap when ground connection made by screwdriver is broken, clean or replace faulty breaker points (par. [84]).
(3) If circuit breaker points are in good condition, but no spark (or a very weak spark) occurs at high‐tension gap, replace condenser (par. [85]) and repeat test under step (1) above. If replacement of condenser does not remedy trouble, replace spark coil (par. [89]).