How long was your hose from the water source and how much of a drop?I got an 8 year old generac and this weekend I tried gravity feeding it. It actually worked quite well. PSI was down from hooking up to the house. I'd say it was running around 1500-1700 psi. Washed the wife's truck and went through about 12 gallons of water. Pump did start to heat up so it gives me an idea.