I'm getting a weak spark (yellowish) off the coil wire - the wire going to the distributor. What could the problem(s) be? If it is the coil and/or the ignition module- is there a way to test these components?
Hi Stan-------------The procedure for testing these and other components in the electrical system is outlined in the factory service manual. There was a manual for 260Z for sale recently in the parts and accessories section of this site. If you can't find a factory manual, get the one by Haynes. It's available at Auto Zone and most other large parts stores. Less than $10, last time I bought one.
Disconnect the 4 pin round connector coming off the COIL. Coil measurements are referenced to the NEGATIVE side of the coil.
This is from the factory service manual and thereby for stock parts:
Measurements taken @ 68 degrees F
Primary Resistance .............= .45 to .55 ohms
Secondary Resistance..........= 8.5k to 12.7k ohms
Ballast Resistor, end to end....= 1.2 to 1.4 ohms
The spark should jump a 7mm gap.
For the Primary resistance make sure you take into account the lead resistance of your meter. Even then it may be closer to 1 ohm.
As far as the Ignition Module, the service manual and Nissan call out a special piece of equipment to check it. But if you verify the COIL as good, have 12 volts to your ignition system, all wiring is good (no cracks, nothing shorted, nothing burnt, connections clean and good, no wires with high resistance) then you should be able to test an ignition module in a known good car. Else the module is probably bad if no spark or if you have a weak spark.