Gold Lifetime Member
Join Date: Aug 2013
Location: San Antonio, TX
Re: Help Plz - Car wont start - Turn ignition and Blow the fuse
Are you talking the fusible link on the main power feed to the firewall connector, or the fusible link on the charge wire from the horn relay bus bar to the battery? If the former, and if all electrical accessories work correctly and the fuse does NOT blow when your ignition switch is turned on, but then DOES blow when you turn it all the way to start (and if the fuse is the right size), clearly the cause is excessive drain through the ignition switch in the start position. That would be from the wire from the ignition switch to the starter. Places it could be shorted include the starter (you already removed this I think), the wire run from the firewall connector across the firewall to the starter (chafed wire?), the firewall passthrough (damaged? or perhaps just no dielectric grease and arcing somehow? not sure if the latter is possible based on contact position), underdash (chafed wire?), or within the ignition switch itself (arced and the start position contact is shorted to ground?). I guess you could have the resistor bypass wire to the coil shorted somehow but I'm not certain that would do it.
I think my approach would be to, with the car turned off, pull apart the firewall connector and take an ohmeter to check for resistance between a good ground and the engine side then the dash side of the ignition wire in the firewall connector. Should be infinite; whichever side is low/no resistance is where your problem is. Could also then pull the plug for the ignition switch off and repeat it with the contact in the plug and the contact in the switch. Should at least narrow down which segment is shorted.
1967 RS driver with a 327/210... but now with an M20, HEI, AAW harness w/ halogens and relays, Dakota Digital, Moto-Lita, TMI interior, and a few other toys