Rig it up so that YOU are the switch. Let switch hang down, Pull the run wire off switch and see if motor stops. If not, it ain't the switch. The coil is picking up voltage somewhere else. How many hot wires to coil/HEI?????
Assuming the run wire from the run position is going to the coil and assuming the start position on the switch has a wire to the starter. Need to know what type starter you have. Solenoid or foot stomp. Did this happen out of the blue or were you tinkering???? "rewiring" something? Replaced something? Come clean now, give it up! Still have a ballast resistor (white ceramic block on firewall) hooked up?
Continuity is a good check BUT if you have 9 volts with the key off, follow the 9 volts backwards !!!!!!!!!!!!!!!!!..to the source. Key off.
Remember, all a switch does is touch things together......whenever in doubt about a switch, disconnect it and touch the stuff together yourself. No need to take switches apart until you prove it is the switch. They can act intermittent and fool a continuity test and/or the minute current in a continuity test is not enough to find bad switch contact engagement.
This trouble is often caused by a misunderstanding of the contacts on back of switch especially regarding: IGN 1 and IGN 2 assuming you have an original style switch.
