Checking spark plugs
(when the engine crankshaft can be rotated by the starter)
Pic. 7.6. Insulator defect
Connect the high voltage spark plug wire to the spark plug removed from the cylinder head. Connect outer electrode (frame) candles with «weight» (with engine bracket), turn the engine crankshaft with the starter. If the spark plug is good, then a spark will jump between the electrodes of the spark plug (rather weak, since the discharge passes in the atmosphere with a small gap). If the spark plug is defective, the spark will not appear due to leakage of charge through the spark plug insulator (pic. 7.6).
Checking high voltage spark plug wires
Check cap and wire insulation for cracks.
Pic. 7.7. Scheme for measuring the resistance of a candle wire
Measure wire resistance (pic. 7.7).
Note. The resistance of the high voltage spark plug wire should not be higher than 10 kOhm (BOUGI) or 22 kOhm (R16AIPS) per meter of wire. If the wire resistance is higher than the specified value, then replace the wire.