911SC won't start

[AUSDave]

Hi all. New to the forum and 911 ownership. Just wanted to ask for some help diagnosing a problem with our car. It's a 1980 911SC LHD from the US purchased earlier this year. Had some issues resolved when we bought it such as overhauled WUR and cold start valve, replaced cracked airbox, new fuel accumulator and some other minor things. I was a mechanic in a previous life and do some basic work on the car. Have changed the plugs, leads and removed the A/C compressor ( so much easier to get to plugs etc)

Anyway the problem is we went on a drive on a fairly hot day recently and the car got very warm and then just died. We let it cool a little and it started but we didn't get far. We let it cool a little longer, it started again but it didn't go far before stopping again. This time it wouldn't start after a very long cool down. We got it towed home and hasn't started since. It turns over easily but has a weak spark. I can hear fuel getting to injectors and smell fuel so i don't suspect its a fuel issue. Coil is original black Bosch - reads 0.5ohm on primary and 720ohms on secondary. I opened the CDI box and visually looks ok but i am not sure what else to check for there. Rotor and dizzy cap look fine.

Any ideas?

I suspect the coil and am thinking of getting an MSD P/N82222 High Vibration Coil. Do these require the non resistor rotor? We currently have the original rotor which looks fine.

I was wondering if anyone with an SC in Adelaide has a known good coil and CDI unit i can borrow to test if one of them is the issue.

Thanks

David

[RDM]

I had a similar intermittent issue that (I believe) was caused by the CDI box. Read down to post 12 (and thereafter) here.

https://forums.pelicanparts.com/porsche-911-technical-forum/958213-memorial-day-diagnosis.html