Engine hesitancy/misfire

[andyelan]

Martin

I had a very similar problem to this on my Europa Special and it was a faulty coil which was breaking down when it got hot. Once the car had stopped for a while, especially if the engine cover was opened, the problem disappeared only to reoccur once the under bonnet temperature built up again. A new coil solved all the problems

With trying to diagnose problems conventional ignition components you should to bear in mind the following
1) The insulation of items like the coil, condenser, rotor arm etc can break down when hot and then recover when cool. Problems will therefore occure only after a few miles running and then disappear again once the car's been stood for a while and cooled down.
2) Its hardest for the ignition to fire the plugs when the cylinder pressure is high which is generally with the enging under load and with high throttle opening. If any components in the ignition systm are below par, therefore, misfires will often occure up under these condition.
3) If the problem is fuel starvation, its very unliky both carburettor float chambers will empty at the same time, therfore the engine will first drop onto just two cylinders before stopping. Ignition components are common, however, so if, for example, its the coil that's faulty, all cylinders would cut out together.
4) If the engine has stopped because of fuel starvation (assuming you've a mechanical pump) it will take a lot of cranking befor it will restart because you've got to refill the float chambers. If its an electrical problem, the engine should restart stright away once everythings cooled down.
5) Don't think that replacing item like rotor arms, condensers etc with new parts will automatically solve a problem. Moderen parts made in China are noware near as good in quality as the old parts used to be.

This has been a bit wordy I know, but hopefully this may give you some food for thought

Andy