No spark with ignition key it run position.

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   I'm getting good spark with the ignition key in the "start" position and the engine seems to want to run; BUT when I let loose of the key and it spring returns to run position, nothing. 

Any ideas?  I seem to have good ground not only at the battery but the engine, starter relay, alternator, etc.

This is in a 1948 CJ2A with:
* 6 to 12v conversion
*single wire GM alternator
* electronic ignition in old-school look distributor housing
* 4-post Ford starter relay

Here is a diagram of my current wiring:

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tbigham Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 08 Mar. 2015 Location: United States Status: Offline Points: 4	Post Options Post Reply Quote tbigham Report Post Thanks(0) Quote Reply Topic: No spark with ignition key it run position. Posted: 08 Mar. 2015 at 7:04am
	I'm getting good spark with the ignition key in the "start" position and the engine seems to want to run; BUT when I let loose of the key and it spring returns to run position, nothing. Any ideas? I seem to have good ground not only at the battery but the engine, starter relay, alternator, etc. This is in a 1948 CJ2A with: * 6 to 12v conversion single wire GM alternator electronic ignition in old-school look distributor housing * 4-post Ford starter relay Here is a diagram of my current wiring:
	javelinadoc SG,UT

rocketeer Members Profile Send Private Message Find Members Posts Add to Buddy List Member Sponsor Member Joined: 26 June 2008 Location: Lehighton, PA Status: Offline Points: 3473	Post Options Post Reply Quote rocketeer Report Post Thanks(1) Quote Reply Posted: 08 Mar. 2015 at 1:28pm
	The easiest way to test the switch would be to disconnect the wire from the switch to the coil at the coil end, connect a voltmeter to the wire and then turn on the key and see if there is voltage. If not then there's a problem with either the wire or the ign switch. To eliminate the wire run the same test but this time connect the voltmeter to the ign post of the switch. If no voltage then the switch is bad. If there is voltage at the post but not the other end of the wire then the wire is bad. Edited by rocketeer - 08 Mar. 2015 at 1:42pm

tbigham Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 08 Mar. 2015 Location: United States Status: Offline Points: 4	Post Options Post Reply Quote tbigham Report Post Thanks(0) Quote Reply Posted: 11 Mar. 2015 at 8:06pm
	Thanks Rocketeer. That makes perfectly good sense. I'll give that a try. I just need a primer on basic function of ignition switches. So here is another basic question, regarding the ignition switch: With the key held in the "start"position, there is obviously current flowing through the ST contact on the back of the switch, BUT, does current also flow through the IGN contact? It would have, too, correct? And when the key returns to the "run" position, after starting, current stops flowing through the ST contact, but continues to flow through the IGN contact, no? Again, thanks for your response.
	javelinadoc SG,UT

rocketeer Members Profile Send Private Message Find Members Posts Add to Buddy List Member Sponsor Member Joined: 26 June 2008 Location: Lehighton, PA Status: Offline Points: 3473	Post Options Post Reply Quote rocketeer Report Post Thanks(0) Quote Reply Posted: 11 Mar. 2015 at 8:25pm
	When you hit "Start" the relay is not only feeding voltage to the starter but also from the "I" post to the coil as I mentioned in an earlier post. Usually that system is used to bypass the resistor during starting. Without seeing your system first hand it's very difficult to figure out exactly how it should be wired since it's not a standard system. After you perform the tests above and determine if that wire has voltage then the next step would be to determine if the voltage remains when you hit "Start". To do that disconnect the cable from the relay to the starter motor then perform the same test as above while holding the key in the "Start" position. If the voltage goes away leave everything wired as it is but if the voltage stays then I would remove the wire that runs from "I" on the relay to the coil.

tbigham Members Profile Send Private Message Find Members Posts Add to Buddy List Member Joined: 08 Mar. 2015 Location: United States Status: Offline Points: 4	Post Options Post Reply Quote tbigham Report Post Thanks(0) Quote Reply Posted: 13 Mar. 2015 at 6:51am
	Thanks for the advice, Rocketeer. Indeed I located the problem: a bad wire from the ignition to the coil. After replacing it the engine started on the first try. Pretty exciting! Which I guess means that the wiring diagram I posted above works. Again, thanks for your input.
	javelinadoc SG,UT

rocketeer Members Profile Send Private Message Find Members Posts Add to Buddy List Member Sponsor Member Joined: 26 June 2008 Location: Lehighton, PA Status: Offline Points: 3473	Post Options Post Reply Quote rocketeer Report Post Thanks(0) Quote Reply Posted: 13 Mar. 2015 at 12:50pm
	Glad you got it going. Larry