12 --- Weak spark at plug or erratic firing
Battery voltage low. In certain conditions low battery charge, especially when coupled with a badly sulphated battery, may result in misfiring. If the battery is in good general condition it should be recharged; an old battery suffering from sulphated plates should be renewed.
Spark plug caps or high tension leads shorting. Check the condition of both these items ensuring that they are in good condition and dry and that the caps are fitted correctly.
Spark plug type incorrect. Fit plugs of correct type and heat range as given in Specifications. In certain conditions a plug of hotter or colder type may be required for normal running.
Ignition timing incorrect. Check the ignition timing.
Faulty ignition coil. Partial failure of the coil internal insulation will diminish the performance of the coil. No repair is possible, a new component must be fitted.
Ignition system fault. Refer to Chapter 6 - Ignition.
© March 2015