240z ignition problem

[mossy]

Got a problem on my 240z ignition, if i hold the key to crank it, all it will do is continue cranking but if i release it, it will start.

[SteveJ]

While it's cranking, see if you're getting 12VDC to ground at the positive terminal of the coil. Most likely, you're having issues with the switch on the back on the ignition key.

[Captain Obvious]

Could also be a problem with the ballast resistor or connections to it maybe?

[SteveJ]

Doubtful, Captain. When the key is in the START position, the Green/White wire gets 12 VDC and doesn't go through the resistor. It goes through the tach and comes out Black/White, going on to the coil. In the ON position, a Black/White wire carries 12 VDC to the ballast resistor and comes out as the Green/White wire described above. Unless someone monkeyed around in the dash harness, the G/W wire should be connected one of the terminals energized when the key is in the START position.

[Zed Head]

Maybe CO meant that both wires are connected through the resistor? Anyway, it sounds like low voltage to the ignition system, or a weak ignition module if it's electronic ignition. When you let go of the key, you get full voltage and a spark and the engine starts.

I had a module that produced a weak spark and the engine would only start with starting fluid. Had to change the module.

You didn't give many details mossy.

[mossy]

I've got the 280zx electronic dizzy and that's right zed head when I release the key it starts up. It makes it a pain to start especially when it's cold as you do t know when to release the key.

I'll check the voltage at the coil while cranking then.

[Zed Head]

Stock coil? Still using the ballast?

Check the connections to the module, and make sure the distributor is grounded well. The current to charge the coil has to pass through the module to ground, you might just have dirty connections.

Forgot to say, to SteveJ's point in#4, if you just installed the distributor you may not have installed the two power wires correctly. One of those details. Is this a new problem on an old setup, or a new setup with new problems?

Edited September 1, 2014 by Zed Head

[mossy]

I'm not real good with all this electronic stuff so bear with me, so I have a 280zx electronic dizzy with e12-80 module, stock coil and no ballast at the coil, when the car was first on the road after being restored a little over a year ago I don't remember having this problem and dash wires are factory and untouched. So I'm guessing if theres nothing wrong at the coil I may need one of these?

Ignition Switch Starter Keys SET Datsun Nissan 240Z 260Z 280Z 510 620 | eBay

Here is a pic of the coil

Edited September 2, 2014 by mossy
added pic

[Zed Head]

SteveJ might have a thought (actually his Post #2 advice is the way to go!). 240Z wiring is odd to me, wires run to all sorts of different places before they get to their primary purpose. By the diagram, two wires should be connected together at the harness, a green with blue stripe (GRN/BLU) and a black with white stripe (BLK/WHT). Then a single BLK/WHTshould connect to the coil positive, along with the wire to the E12-80, which I assume is the big red one in your picture.

And that seems to be what your picture shows. The diagram also shows a separate wire to the starter solenoid. So you may be right, you need a new switch. SO, as I've done before, I've distracted someone from the good initial advice - check the coil positive for voltage with the key turned to Start. You don't even need to disconnect anything, just stick the probe on coil +, and the other to ground, then turn the key. You'll probably see it jump to 12 with the key On then drop to zero at Start.

Here's a link to a 71 diagram. http://www.atlanticz.ca/zclub/techtips/wiringdiagrams/240z/1971_240z.gif

Thanks for letting me work on your puzzle and sorry for delaying you from the fix!

[Captain Obvious]

I have no ballast at the coil

My keen troubleshooting skills are now telling me that it's not the ballast resistor or the connections to it.

You can disregard my previous input.

I'd take a look at the switch on the back of the ignition key assy.

[mossy]

I'd take a look at the switch on the back of the ignition key assy.

Looks like this might be the culprit then, I tested for voltage at the coil and had 0 volts at accessories, 12v at on position and when cranking 0 volts again. Thanks for everyones help I'll keep you posted on the outcome.

[mossy]

Quick update, bought a new ignition from ebay and problem solved starts straight away!