1973 Scamp won't start in start only in run. With a Twist....

Have checked all the wiring I can think of and they check good. I have a new ECU and ballast resistor. Got 5.5 volts in run and 10.5 volts in start at the coil. Have jumped straight from the battery to the positive of the coil. Also the coil negative straight to ground on the battery. Still won't start in start except VERY intermittently. What the? Any ideas?