I believe the whole system is responsible for keeping the fluid from draining due to gravity as it should be a closed system. If I recall correctly the pump is a bi-directional pump, pumps one direction for fluid to the front of the vehicle and the other direction for the rear window washer nozzle.

 

The headlight washer and windshield wiper systems have independent circuits.
In the pump (number 11), in the spray nozzles (numbers 1 and 2) or in lift cylinders (number 3) there should be some system that prevents the release of liquid when the pump does not send pressure.

I'll have to take it all apart and see what's wrong.

 

Edited.

 

Thank you, I will try that