Did you prime fully?
I think I've figured out your problem.
Over priming. More than three strokes of the Knob BEFORE turning the old girl on, often leads to erratic performance. If you stroke too many times, it can lead to a prematurely flooded bore, and that leads to erratic behavior for quite a while especially if by that time your battery has gone flat! In that case you have to wait a while for he battery to recover before giving it another go, but whatever you do, don't overdo it this time or your battery will be done before you manage to get her going. You might as well give up for the day in that case.
Equally you have to be careful not to UNDER PRIME. There is nothing worse than not pumping enough, not getting enough into the bores. If that happens she'll never get going and you'll be looking at some heavy maintenance bills if this continues for any length of time. If you are constantly under priming, it may be that you have a worn primer. As these get older they start to fail, not pumping enough in or leaking. In that case you should go and see someone who maybe able to give it an overhaul to increase pressure again.
I can never understand my old girl. One day she fires up at the first touch, others I can be pumping quite a few times and she never wants to gets started. In that case I just pump like mad for a few seconds then go for it, that normally gets her sparks lit.
I guess they all are a bit temperamental - even modern ones who like the red knob all the way out to start with then shoved right in at the first cough with no pumping or anything....
Anyway good luck.
PS What sort of Van was it?