FredR

A fully charged battery in good condition should show something in the region of 12.6 to 12.8 volts. If there is no load in the system then the battery and jump post should show the same value. Invariably there will be some small current flow. When everything is shutdown and locked the current draw should be about 30mA if the system is leakproof. The 12.3 volts at the jump post suggests to me more amps are flowing than should be the case. If I get chance tomorrow I will check the voltage on my jump post for comparison purposes.

Musse

Thanks for the input Fred. First thing I did this morning was check the voltage at the battery against the voltage at the jump post and then read more or less the same. 13,4 (fully charged) vs 13,2 at the jump post.

We then attempted to start again. One injector seemed to work and one cylinder fired. We read about ~9 at the jump post while cranking.

Next we pulled one of the injector connectors and saw 12 volts. So AFAIK, this meant we did not have a short in the injector harness. We then provided 12v + a ground directly to the injector and it didn't open - so we realized we might be dealing with stuck injectors. The car has been idle for ~20 years so it made sense it could be the cause. After applying 12v for a while, lightly tapping it, plus using a heat gun carefully, the injector become unstuck. After reconnecting it we then had 2 cylinders firing and this was strong indicator that the other injectors were also stuck. One by one we went through the injectors to get them unstuck using the same methods and finally - voilá! It started right away and runs smoothly!

After ensuring nothing leaked, we took it for it's first 3km drive in almost 20 years. It went perfectly, breaks, clutch (bleed earlier the same day), steering etc. was perfect. Some slight vibrations liely due to the tires not being rotated very often (fingers crossed this will improve as I drive more and more).

This has been a ~ 2 year on-and-off project. Starting with pulling the engine in 2022 - a huge thanks to the patient and helpful 928 Rennlist community! Here's a photo of the car right before the first drive

FredR

Some good progress. These cars do not like to sit idle for too long. Sounds as though you need to remove the injectors and get them ultrasonically cleaned and tested.

If the tyres have been on the car for 20 years then you need to ditch them pronto and get new rubber.

Alan

I’d suggest you replace the battery ground strap. Cleaning may not be sufficient. If the battery is not new - replace it too - it may have developed a higher internal resistance that will affect cranking current - and recharge rate. If it’s new that is unlikely.

Alan