Simple explanation of system
Rotating reluctor produces a spark, this spark is amplified by amplifier and drives the negative of the coil to ground, thus producing spark at plug.
Common ignition problems are ........
Non genuine spares fitted to ignition system, in particular rotor arm,dizzy cap and leads causing....
Rotor arm shorts through brass contact reducing spark
Dizzy shorts causing poor spark
Leads break down causing poor / intermittent spark
Relace all with genuine Lucas or Bosch
Stuck or fallen off bob weights.... twist rotor arm , should spring back
Amplifier, usually fails open circuit... no spark at all.
Repalace with new type, ( do not overtighten ) about £24 with grease, new plug and crimps
Reluctor coil fails o/c on lead ends or internally ... replace ...Expensive
If you remove the dizzy make certain you mark the position of the rotor arm before you remove.... ( Take a picture ) and mark the body of dizzy to block.
It can be replaced 180 deg out and will not work at all.
Check connections to all ignition components, push home and re-crimp where required
Try removing condenser while you trace fault, these can short out.
Other common faults apart from pump etc are coolant sensor, if this fails you may not be able to start easily and when you do the car will probably run ok while hot but not start again when cold. Shows up as flooded plugs
Don't forget to check all air hoses for leaks and check,clean or replace crank case breather filter
Good Luck
Fred