Jonathan Spencer wrote:
About a week later I had the trailer ready and she started after a bit
of persuasion. (It's very easy to flood the engine with too much
choke.) We let it idles for maybe 10 minutes and then untied the warps.
Once out in the river, it was my intention to give her a good thrash up
and down by way of a workout. But the engine would rev up to maybe half
speed, run for a short while (not more than a minute) and then cut out.
Turning the key to crank got it going again but it repeated this several
times. So we made out way to the jetty by the ramp and hauled her onto
the trailer. That's as much as I can say.

It could be the fuel pump or a clogged fuel filter.