zjkim

First time poster here. Have a '78 SC w/ 52k miles. However, having some issues with the car dying after the engine is warmed up. Basically the car runs perfectly when cold, but after 5-10 minutes of engine being at operating temp, engine cuts out and won't start back until the engine has cooled. Any suggestions? Thanks.

Steve Weiner-Rennsport Systems

Hi,

Welcome to Rennlist!!!

To troubleshoot and fix the problem, you need to find out whether its an ignition or fuel related problem.

I would check the ignition by snapping an extra plug into #1's plug wire, ground it, and then crank the engine, watching the plug for a nice fat blue spark. You may need a helper to do this. If you see a good spark, its time to check the fuel pump and relay for a problem.

If you don't see a spark, you may have either a coil or CD Ignition box failure.

wwest

Use water spray to cool the CDI box and see if it restarts.

Porsche did not choose the best semiconductors of the era.

Should the above procedure work then look into the alternator/VR output voltage as measured in the engine compartment.

CDI is not well protected from over-voltage (>15 volts) events and our ('78 Targa) cars seem to be especially subject to battery over charging.

wwest

Steve,

Would it not be a bit easier to test for spark using the wire removed from the center of the distributer cap?

theiceman

either way works . centre distributor sure snaps pretty good.