My 260z has a Mallory Unilite distributor, promaster Coil (#29440), and a Mallory Ignition Active Power Filter. Starting this year, when I drive it a short distance the engine just dies. When I go through the Unilite diagnotics, it show the ignition module has failed the test where I measure the voltage between the negative side of the coil and a ground with both the ignition module LED blocked and open. I've tried replacing the ignition module but the problem persists. Mallory's tech suggested a better coil ground so it now has a dedicated ground wire going directly to the battery.

I can restart the car after it sits until the engine compartment cools down. The ignition module then reads good. It will run for just a couple of minutes but again shuts down.

I don't think the fuel tank is building up a vacuum because opening the cap doesn't result in a rush of air and doing so will not start the car up again.

I recently added a new radiator cooling fan to replace a fan that stalls and draws a high current and installed an under engine splash guard so I should be getting better air circulation. I got rid of the dead head fuel system a PO installed and the fuel now flows back to the tank to minimize vapor lock. The fuel pressure gauge shows adequate fuel pressure.

Should I try a new coil or power filter?

1 minute ago, Jeff Berk said:

it show the ignition module has failed the test where I measure the voltage between the negative side of the coil and a ground with both the ignition module LED blocked and open. I've tried replacing the ignition module but the problem persists. Mallory's tech suggested a better coil ground so it now has a dedicated ground wire going directly to the battery.

Maybe it needs a better module ground. And/or heat sink.

The module looks like the typical GM module that grounds through the mounting points, and sinks heat through the contact of the bottom with the mounting surface.

Edited 1 hour ago1 hr by Zed Head