QuestionQUESTION: I am able to start my car but as soon as I set the key to the run position it stops. The car has nut run in about 5 years and none of the other electrical parts work. It does have a new battery though.
ANSWER: Noah,
The late Spitfires had an ignition system with a 6V coil and a ballast resistor in the wiring harness. So there are actually 2 power connections to the coil.
Normally power to the coil goes through the ballast resistor and the coil sees the approx 6V it needs for normal running.
When you run the starter the ballast resistor is bypassed and the coil sees full battery voltage.. somewhere between 8-10 volts as the starter motor cranks the engine.
On your car it sounds like the ballast resistor part of the circuit is missing or damaged. An easy test is to hook a voltmeter to the coil (+) lead and see if there is voltage with the key in the "run" position, engine off.
The other possibility is a fault with the electrical part of the ignition switch.
Cheers,
Jim
---------- FOLLOW-UP ----------
QUESTION: I can't check the coil right now (middle of the night). Could you address the possibility of a problem with the anti run on valve?
AnswerNoah,
If the oil light is going out as the engine is trying to start, it's not likely to be a an anti-run on valve issue.
The anti-run on valve is tied into the oil pressure switch. In proper operation, as the engine slows down (and oil pressure drops) the anti-run on valve vents the intake to atmosphere, making sure the engine isn't pulling in fuel and trying to keep running.
Why not do a voltmeter test on the coil first before borrowing other trouble?
Cheers,
Jim
