So the pressure is too low.
Is the limiting valve set correctly?
Can you check the pressure between the pump and the control valve?
If it remains low before the valve, I'm afraid, you'll have to do something with the gear pump.

I am having the same problem with a H20T, tilt, sideshift and steering all appear to be working, but lift is weak.
Empty forks move as if all were well, but with a load on lift is slow if at all.
I checked the pressure at port marked MP on the control valve, and get a reading of 1500PSI. The internet shows this pump as being able to produce 320bar. (4500PSI)
Is there anyone who has a breakdown of the valve and where the relief valves and test ports are located for lift and other functions?
Any other suggestions and comments welcome.

Hi Swoop223,
You're definitely right.
I think, the pressure check should be the FIRST thing to do, before the pump replacement.

thanks Karait, terminology wasn't correct for the pump(s), but i still wonder if he checked the pressures after replacing that pump and set them.

Swoop223,

On Linde 350's there's a hydrostic (multipiston) pump for travel and a tandem gear pump for hydraulics, steering and hydrostat boost.
So, generally, adem k concluded it right replacing the gear pump.

When you say "gear pump" do you mean the main pump? Or the hyd pump? Or both?
It's been a while since i worked on a H20 but.i seem to remember the main pump for propulsion and the hyd pump piggy backed on it for hyd.
does that sound about right?
So which one did you replace and did you set the relief pressures after installing?

How about the hydrostatic steering?
Is it smooth?

How about the other functions (tilt, siedeshift).
Are they working properly?

Are you able to measure the pressure in the working hydraulics?
You should have (depending upon the truck capacity and the type of the mast) something between 165 and 250 bar.

Is the pressure limiting valve properly set?
The valve is located low, on the first, control section of the control valve. You may check, if it didn't stuck.

Are there no nozzles in the control valve lift/lower section?
Remove the hydraulic hoses from the first section and look inside.
If you find some rings with small diameter hole in it - remove them.

Well.. enough for now.

Good luck