74 road runner starts when key is released from start

[flamesoldier]

My 74 road runner will crank for ever and wont start until i stop and release from cranking it starts. I have 12v going to both sides of ballast what is this issue?

 

[Don Frelier]

I'll bet you don't have 12 volts during cranking your probably just checking it in the run position.
Usually bulkhead connector.

 

[Kern Dog]

I have this same issue with this truck:

It is difficult to pin down, too.
It often happens upon first start after sitting. Sometimes it does it after I've driven it awhile.
I've changed ballast resistors and ignition switches and the problem persists. It costs nothing to pull the bulkhead plugs and clean the terminals but I don't know if that is the problem. I have power enough to crank, the radio works, the wipers and lights too.

 

[Nacho-RT74]

Ign switch fail or some problem on brown circuit between ign switch and ballast.

mostly sure you loose also the brake light on cluster while cranking.

 

[SMS68]

If you have a replacement ignition switch, there is an 18ga black wire that has to be removed on some applications. Not sure if that’s your issue, but it might be worth checking.

 

[72RoadrunnerGTX]

The small black wire on replace later ignition switches would not be involved with starting. Assuming a stock ’74 ignition system, as Nacho mentions, disconnect the ballast resistor leads and verify +12v on the brown wire (Ign2) while cranking. This symptom normally points to a failure of one of the resistors in the dual ballast resistor. Do a continuity check on both resistors.

 

[Nacho-RT74]

Failure on resistor would be backwards… starting while cranking and cutting when releasing the key but this could be posible just on points car, because on elect ign the resistor failure won’t allow to feed the ECU while cranking either.

in this case if engine starts up when key is released, the coil is still getting the juice throught the resistor, hence why I point out to some missing connection between ign switch and brown wire at resistor. Either ign switch plug or bulkhead. Even ign switch itself.

 

[It’s just me]

My 74 road runner will crank for ever and wont start until i stop and release from cranking it starts. I have 12v going to both sides of ballast what is this issue?

I’m having this issue now. What did you do to resolve the issue?