engine ignition issues

[spidee1666]

HI, my name is Ryan and I'm working with a friend on a couple of 1972 240z's. These cars are awesome and fun to work on. The problem we're having with one is that we can get it to start fine, but in order to keep it running we have to hold the key just past the on position. Not engaging the starter, in between the on and start position. As soon as we let the key go and it goes back to the on position the engine dies.

We already tried switching out the key switches on the steering column and that didn't work. Also checked fuses but may just try replacing some, just in case. Any help would be great. Thanks

Ryan

[Carl Beck]

Hi Ryan:

As I recall..... when you have the ignition switch on the "START" position, it by-passes the ballast resister and feeds 12 volts directly to the coil, when the switch returns to the "RUN" position the voltage going to the coil, is run though the ballast resister....

So if you have checked the ignition switch - check to see if you are getting voltage through the ballast resister. Many times it is as simple as a bad connection, broken wire or lose connection.

Good luck,

Carl B.

[Nissanman]

Hi Ryan,

when you crank and start the engine, the ignition ballast resistor is bypassed, thus providing the full battery voltage to the ignition circuit.

Once it fires and you [normally] return the key switch to the "ON" position, the ballast resistor is switched into service, reducing the ignition voltage to less than battery.

Sooo, if replacing the ignition switch didn't help, you need to determine if that ballast resistor wiring is good.

If you have a multimeter, check the continuity of the resistor, disconnect wiring first.

Alternatively, check at the ballast for correct voltages, wiring connected.

You could prove the resistor faulty by simply bridging it out, but don't run it for long like that, the coil will overheat.

It appears great minds think alike AND at the same time!

[spidee1666]

Thanks guys...I'll give those ideas and methods a try. I'll let you know if I have luck with fixing the problem.

Thanks again,

Ryan

[spidee1666]

Thanks again guys I got in working. I'm not sure if it was the ballast resistor or not, but it was a loose wire on a ceramic resistor that is connected to the distributor cap. Mounted up by the front of the engine compartment on the drivers side.

[=Enigma=]

Yup, that would be the ballast resistor.