Previous posts will indicate that I had a similar problem on a '71 4/4 fitted with Lumenition electronic ignition. I bought and fitted a new coil and ballast resistor but after installation I found that the car wouldn't start at all. I then found that the "king" lead (coil to distributor) had a possible break in the carbon core. I fitted an old lead I had kicking around and the car started instantly and has run without interruption so far.
