Check firstly the solenoid connection on the starter, a spade connector prone to corrosion and working loose. Clean and tighten it.
This fault shows as intermittent no crank.
Check firstly the solenoid connection on the starter, a spade connector prone to corrosion and loose. Clean and tighten it.
This fault shows as intermittent no crank.
I'm not much use on these kind of problems but have you tried a 220 ohm resistor across the plug terminals?
Also probably needs a new pressure cap as it shouldn't have blown with only 3/4 reading on gauge.