I have a 1978 lifted bronco with 400m and 4 speed manual trans. which currently has had the following replacements: Starter, alternator, voltage regulator (5th one), ignition switch, battery (optimum red top), and other various parts.
Issue:
The vehicle does not need the clutch engaged to start in the nuetral position. However if you have a gear selected and do not engage the clutch the vehicle jumps forward...obviously...but when you push the clutch back in and go to drive the starter keeps kicking over even if you take the key to the off position and remove it. normally i remove the battery terminal but before i could the negative cable melted.
Now before this happend it was charging at 18 volts and when i took it to checker to be looked at we would put the test machine on the battery and this would cause the starter to keep kicking until the battery tester was removed from the battery leads. I was told replace the ignition as the regulator replaced new already and fine. I did. This fixed the 18 volt charge back to 14 so thought it was fixed. Then every once in awhile the car wouldn't kick over unless i jiggled the ignition then pow it starts. NOw after forgetting to push in the clutch with gear in and the negative battery cable melted it wont kick over but everything comes on like normal with another brand new red top battery and voltage regulator. The starter just wont engage...
This is driving me absolutely crazy at this point...
All the negative battery cables are attached and fuses are good...no burnt wires beside where the negative battery end melted on the battery.
I was told it could be a short somewhere but i can't find a short from the ignition to the battery. I was told theres a switch or something in the clutch peddle that could be bad and cause this...this is the only part i havn't replaced.
If anyone has any idea of what to do or who to have check it..PLEASE...i begging help i'm on my last straw...
Thanks

 

I've had something like that happen when I put the ignition module from a different truck in mine. Just kept cranking. never really knew why. I doubt that is your problem though

There was no clutch switch on my 78 bronco...If it has to do w/ the clutch, could be something to do w/ the fact it's mechanical, and if your mounts are bad it will move the body on the frame. Possibly putting power to/touching together the Red/Bl wire that goes to your soleniod??

 

The starter solenoid could be bad. You don't mention anything about checking or changing the starter solenoid up by the battery. Small wire hooked to the solenoid that is the farthest forward( should have a S above the wire on the solenoid) Should get power when you turn key to crank position. If you are getting power when in crank. Then make sure tranny in nuetral and jump the two big posts on the side of the solenoid( I use a big pair of pliers without insulated handles.) If starter cranks, replace solenoid. If starter doesn't crank, Starter bad. providing you have power to the front big post on solenoid.

Also need to see if it has a clutch switch or not.

I was replacing voltage regulators fairly often, The alternator shop told me the regulator was not getting a good ground.( my screws that mounted it to the fenderwell did not tighten down real good. Redrilled new mounting holes and put new bolts in and haven't replaced one since.