My HF 6000lb midrise lift has been going strong for almost a decade and it's been great -- until this morning. I tried to lift my 2011 Cadillac DTS to inspect the brakes and the steering rack, and was instantly disappointed because the lift wouldn't budge the car -- not one inch.
It didn't make sense because I've lifted all my vehicles (including my '03 Dodge Dakota 4x4) without much hassle. After a thorough inspection of the oil level, the cylinders and the hose I came to the conclusion that it's a possible pressure problem.
Most all 120v and 240V Chinese electric/hydraulic power units have a pressure adjustment valve on the side of the pump. Here's mine -- covered by a large plastic hex cap, or on other manufcaturers units I've seen them use just a plug.
Underneath the cap is a slotted adjustment valve that you turn with a large flat blade screwdriver to the right (clockwise) to increase pressure, and to the left (counterclockwise) to decrease pressure. To fine tune it I hit the lift button while at the same time turning the valve adjustment clockwise until the lift started to move the load - then another 1/4 turn. In less than a minute my old lift was moving a 4300lb Caddy up and down without a problem.
Assuming that all other components are in good shape, a slight pressure adjustment on your lift may be necessary to lift heavier loads. These pumps are set to a medium range at the factory to increase motor and pump life and for most of my use over the years that was enough. For this Caddy, I had to adjust on the fly --
A word of CAUTION -- like all things it's easy to go overboard with the adjustment. If a little adjustment is good, then a large adjustment isn't necessarily better -- the pump and motor will work harder as the pressure increases.
