Your battery is dead.
What is the voltage at the battery "at rest" and when it drops at 3 seconds of hydraulic stall?
Other things to check include the suction hose for collapsing or pin hole suction causing foaming of hydraulic oil.
Check pressure not so much under load, but at max stroke of hydraulic cylinder (lift would be best, this avoids a most of the possibility of bypass in the cylinder).
This is ONLY to be used to report flooding, spam, advertising and problematic (harassing, abusive or crude) posts.