How did you hook the garden hose up?
Mine has a 'T' just after the gate valve off of the pump, and water goes both ways- to the motor and to the pump, helps keeping the wear ring/impeller lubed/cool. Some of the water drains out the pump intake, even after the hose is off.
Try the 'Below Needles Bridge' on the U. S. Bureau of Reclamation, Lower Colorado Region. Hourly data.
The water is let out at Davis Dam, 4600 cfs is about 1 unit. Note the hour of release.
Below Needles Bridge is the next stream gage...
Everything would need to be swapped.
Distributor and ignition system.
Oil cooler and power steering cooler.
Front accessory drive and components, water pump, alternator, power steering pump and sea water pump.
Flywheel, drive hub, and starter.