Yeah, those switches can show their age after 40+ years. It was just worn out.

Excellent! Cheap easy fix.

Most likely, you're having issues with the switch on the back on the ignition key.

SteveJ nailed it!

Excellent! Cheap easy fix.

SteveJ nailed it!

That's only because I spend too much time reading threads here and over at Zcar.com.

There have been many similar threads over the past 18 or so years.

I wish I saw this post earlier as I had the same problem years ago and figured it out.

The interim trick to get out of trouble is to only turn the key ~ 90% of the way to full-stop when cranking.

The underlying problem is that the contact for the ignition in the ignition switch is not making (probably due to carbon or corrosion) however the contact for the starter in the ignition switch is making....thus you get the starter but not the spark. If you only turn enough so that both contacts are making and avoid the carbon patch, it will both crank and spark.

The fix is to change the ignition switch or to really douse it with contact cleaner.

Here is the required replacement part:

Edited September 12, 201410 yr by Blue

Yep. That's the part. I was just too lazy to search for it for my original post. As a matter of fact, Phil, I think you posted that solution in one or more of the threads I have read addressing this problem.

And here's why it needs to be replaced:

Well it looks like I spoke too soon, new ignition looks to have failed on me after trying it for the second time today, accessories are on but no cranking and I plugged the factory one back in to check and it started with that. I also had taken the module off the back of the factory ignition too have a look inside but bolted it back together after needing it again and now it works like normal.

I was keeping my mouth shut (fingers off the keyboard?) until I was fairly sure. I think the switch you bought is for a ZX. I'm not completely sure about the cross compatibility. I have one sitting around at home along with a Beck-Arnley S30 style switch (Amazon.com: Beck Arnley 201-1179 Key, Lock And Ignition Switch Assembly: Automotive). I haven't tested the style you put in your Z, but I know the Beck-Arnley part works fine since I have it in my 260Z.

Here's a good reference on the electrical switch - Ignition Switch 70-83 (Electrical): 280 ZX 79-83 #4 - Electrical 4 - Misc Electrical 4 - 20098-EPBE - Z Specialties Online Store - If we don't have it in stock, we can get it!

I was keeping my mouth shut (fingers off the keyboard?) until I was fairly sure. I think the switch you bought is for a ZX. I'm not completely sure about the cross compatibility. I have one sitting around at home along with a Beck-Arnley S30 style switch (Amazon.com: Beck Arnley 201-1179 Key, Lock And Ignition Switch Assembly: Automotive). I haven't tested the style you put in your Z, but I know the Beck-Arnley part works fine since I have it in my 260Z.

Thats dissapointing if thats the case steve as I asked if it was plug and play for a 240z before I bought it, I have contacted the seller about a replacement just waiting to see who pays postage though.

Here's a good reference on the electrical switch - Ignition Switch 70-83 (Electrical): 280 ZX 79-83 #4 - Electrical 4 - Misc Electrical 4 - 20098-EPBE - Z Specialties Online Store - If we don't have it in stock, we can get it!

I see the back of those modules look different to mine as well, they have two screws on the module whereas mine has one (71 240z) and the size of my module is a lot smaller on the back.

Edited September 14, 201410 yr by mossy