Genie GS1930 will not lift two people

[FrozenR190]

The Genie GS1930 scissor lift will work with one person seeming just fine but will not go up with two people in it. Did find older thread on this too which was very helpful. Tested pressure at test port at about 2400lb. On the valve block turned system relief valve and lift relief valve all the way in (about 3 turns) and pressure only increased to about 2600lb-2700lb. Still will not lift two people. Book said to set at 1800 to 3700. Took apart the adjustable relief valves and found no noticeable problems. Put gauge on line out of pump and only get 2500lb. Didn't know if air in line at that test could skew pressure reading. Should the pump higher? Removed return line and when raising for the first moment no oil comes out but then flows starts (when lift goes up). Any suggestions or input would be great. I see in the manual some models could have a overload relief on the lift cylinder but I don't think this one does. It's GS1930 GS3008B-96718 serial#

 

[Rick39]

Put two people on it and try to lift. Hold it on lift up when it stops and allow it to struggle for 10 seconds or so.

I'll bet the pump will be nearly hot enough to burn your hand after that.

I'll also bet that the oil looks like chocolate milk instead of cherry juice.

Every one of the dozens that I've seen with that issue was the pump. There is a kit to change it to new style but you can get away with just changing pumps.

 

[FrozenR190]

The lift is low hours and oil very clean. Doesn't seem to run hot. However I have not worked it for 10 seconds when it stops lifting. I'll run it longer and see if it heats up. Thanks. Is there a simple way to test pump? The way it returns oil when lifting seems make me think it's by passing pressure off somewhere.

 

[Rick39]

If it returns a good flow of oil when trying to lift but not moving then the pump may be OK.

I had a few that had motor controller issues causing lift problems but those were older than yours.

The simplest way to check a pump is the heat test. Get them to put two guys on the lift, let the motor run for a little while while unsuccessfully trying to lift, and feel the pump.

Either that or run the motor on full voltage, restrict the flow to build up pressure, and test the flow.

 

[FrozenR190]

Looks like it is the pump. Before replacing pump I tied lift cylinder line directly to pump ..... to bypass the pressure relief valves. Still would not go up with the weight of more than one person on. Ordered new pump and put it on. Now works good. Little surprised pump would be worn out on 360Hr machine but I'm learning.

 

[92U 3406]

My first guess was the pump was worn out. Seen it a couple times. Little trick with hydraulics, heat indicates an internal leak. If you held the function for 20 or so seconds I bet the pump would have been very hot.

Also on those lifts I believe the hourmeter only counts when a function is actually in use. Gotta think that 360 hours is a lot of up/down or travelling. We change oil/filter in our electric scissors every 100 hours/annually (whichever comes first). Also keep an eye on the hydraulic lines to the front drive wheels, they tend to crack and break over time due to the steering angles.

 

[Rick39]

I agree, 360 hours is a fair number of hours on an electric unit, figure one hour on an electric is 10 on an IC machine.

Again, I will bet that the hydraulic oil is badly contaminated.

I've seen dozens of those pumps fail and every one had the remains of ground up pump mixed in with the hydraulic oil.