<VV> Hard/non-starting 110

[Tom Berg]

My neglected '61 Rampside has a 110 engine (from a '65 or so car) that starts fine when cold. But drive it a while and shut it off, and it will crank slowly (errr, errr, errrrrr, errrrrrrrrr) but not enough to restart the engine. The battery is OK (about three years old and was used to start my '64 a few weeks ago). Jumping the battery (with my Costco charger/starter) doesn't help much; the cranking motor turns a bit faster, but again, not enough. 
But if I leave the car for a little while and return to it, the engine will start. That sounds like vapor lock, right? But the truck has an electric pump that keeps working. Next time I'll carry a bottle of water and pour it over the fuel lines and pump, then see what happens.
Meanwhile, any thoughts? 
--Tom in Ohio