914 Won't Start Properly When Cold

It does it in the morning if it's cold after flying the previous day so on the ground for maybe 18 hours max. It can happen the same day if not started for several hours, but usually it's fine after the fisrt start.

Electric pumps would be on just before starting so not for any length of time.

Thanks Bill !

A guy at my local airport had a similar problem and it turned out that his choke cables were sticking and thus the starting carbs were not being properly activated.  Can you verify that the choke levers on the carbs are moving to their proper positions?

Thanks - yes triple checked that and swapped the complete carbs with spares, but no change :-(

I think you have an electrical problem not making proper connection during cold as you indicated 40 F. 

Did you try heating all electrical connections with say a hair dryer or heat gun carefully on low heat and start the engine and see if it is ok. You basically are simulating starting engine during warm ambient temperature. 

Another way is try starting engine on one module switch. Let it run few seconds and shut down if it starts and go feel the cylinders. The one that is cold is the problem. If all hot, let it cool and try same with other switch on only. If you do find a cold cylinder, back track and trouble shoot wiring to final spark to that cylinder. Don't preheat while doing procedure in this paragraph. Take extra care making sure no one is near prop if you get help. 

We did try warming the ignition modules as they are known to have issues at low temperatures and it seemed to help the starting, but we proved it wasn't them by (temporarily) installing brand new units. Looks like the general warming of the engine area helped so we will see if we can try and narrow down which part needs to be warmed.

The problem happens with either both or just ignition circuit A or circuit B selected. We did check the temperature of each cylinder with both ignition circuits on and it running like in the video and found they were all warm. We will try it with only one ignition circuit live to see if that shows up anything.

Thanks to all for the input !