When I change my fuel filters, I have to turn over my starter for more than a minute and do it in 20 second intervals with a few minutes between each interval so the starter doesn't overheat. (I have a '98 e300). That is to get enough fuel into the system. I suspect you have to do the same.

Are you using a block heater? You may need one to start an '83 diesel in 20 degree temperatures that hasn't been started in 15 years. At 20 degrees you are getting into a temperature area where some people routinely use block heaters on older diesels.

If you are not using a block heater, I suspect you would be best off to wait until the temperature has been above 50 degrees before you try to start the car again. Wait until the second day so the temperature of the motor rises.

There are lots of people who know more about '83 240s than I do. Give some of them time to weigh in before you do much more.