Re: Restart is hard after the winter
10V is a healthy voltage while cranking. It is not such a healthy voltage while just the glow plugs are on.
I have a 3 cyl Kubota, and I can tell you with hot glow plugs and a healthy battery it will start up as soon as I think about touching the start button.
You don't need starter fluid, or a new battery (given that you say it turns over healthily, you need to methodically figure out what the problem is. You need compression, fuel, air, and maybe some heat, and it will start. Find out which one is missing.
The clue might be in the history. What did you do last?
You say there is no air in the fuel. How do you KNOW? I suggest bleeding from the screw right on the fuel injection pump body. This would be my very first step if my engine turned over but did not start.
1984 Bristol 31.1
Alameda, California, USA