240z ignition help

[280znewbie]

I picked up a 71 manual 240z. I can't get any spark from it at all. I have check the points gap which was .018. I have voltage to positive side of coil at both key on and start position. I have used a ohm meter to check that the plug on the distributor is grounded and it is when the point is closed. I have full battery voltage at the negative side of the coil as well as the wire from the coil to the cap. What would be the issue? A condenser of some sort?

Edited June 14, 2016 by 280znewbie

[Chickenman]

Pop the cap off and rotate the motor until the points open.  When the points are open ( key on of course )  you should have zero voltage on the negative side of the coil terminal. Have someone crank the car while you observe the points. If you see a spark at the point contacts when they open, that indicates a bad points condenser. A bad condenser will cause a weak or no spark problem. Check the condition of the points and make sure they are not burned or badly corroded. 

 

A quick way to test the points system is to put a 12v test light, ground the alligator clip to chassis and hold the test light tip on the negative terminal. If the test light pules that indicates that the point system is working correctly. If the test light stays on or off steady, or flickers weakly then you know you have a problem with the points system. If the test light pulses strongly, then you likely have a bad coil ( assuming still no spark from coil Hi Tension lead ).

 

Of course, do check the resistance of the Hi Tension coil lead. Make sure it's not not " Open "

 

Here's a good article on how to test points. This is on a VW, but it's a universal method for all points systems.

 

http://www.shoptalkforums.com/viewtopic.php?t=123687

[Chickenman]

Edit: And please don't start the same thread in different places. That gets hard to follow. Stick to one thread.

[NewZed]

I think that you meant zero current when the points are open, not voltage.  He'll have battery voltage when the points are open, and a voltage drop when the points are closed.  Points are the switch to ground.

[280znewbie]

Thanks both of u for that info. Unfortunately that's stuff that I've checked for the most part. I just need to use a test light on the coil to check for pulse. Im thinking the condensor is bad. Does it mount on the distributor or the fender?

Edited June 15, 2016 by 280znewbie

[280znewbie]

Also I've noticed when the points are closed I still have full 12v on the negative post, is that a ground issue on the distributor or a problem with the condenser?

Edited June 15, 2016 by 280znewbie

[beermanpete]

If you have 12 volts on the negative coil terminal when the points are closed there is an open circuit between the coil and ground. The path is through the wire leading from the coil to distributor body, feed through, internal wire between the feed through and points, points, ground lead within the distributor, distributor body, and engine block. Try using a test light. Connect the ground clip to the negative side of the coil and make sure it lights when toughing the probe to the ground. Next, place the probe on each of the various circuit nodes in the circuit (with the points closed) starting at the coil moving towards the engine block. The light should be out at each node until you get to a point past the break in the circuit. When the light comes on you will know the fault is between the points where the light is off and on.