A 1 HP, 10 GPM pump, lifting from 300', can only produce 38 PSI. From 340' it can only produce 21 PSI. If it was a 1 HP, 10 GPM pump, it probably overheated because it couldn't build up to 40 or 50 and shut off. If it is a 1 HP, 7 GPM pump. it will produce about 6 GPM and can build enough pressure to shut itself off. A 1.5 HP, 10 GPM pump will deliver about 12 GPM from 300' and 40 PSI, and can shut itself off.