Discussion:
Toyota 7FGCU25 slow hydraulics

This machine has a bail clamp on it. When operating the clamp or tilting, the hydraulics slow down when you throttle it up high. The clamp and tilt go about 1/2 speed and you can tell that a releif valve has opened. If you let the rpms go back down low the valve seems to close and the movement speeds up. Any ideas where to start checking the control valve that has lots of valves on it (SAS and seat switch)? Thanks for and ideas.
  • Posted 8 Feb 2011 08:33
  • By mrfixit
  • joined 11 Dec'08 - 1,434 messages
  • New York, United States
Showing items 1 - 4 of 4 results.
Hi!
Check for the suction pump filter,i had a similar problem once but all hidraulic functions were afected.

Regards!
  • Posted 12 Feb 2011 03:09
  • By feitor
  • joined 6 Jan'11 - 161 messages
  • Leiria, Portugal
my email: rc.feitor@hotmail.com
it is possible (not likely) that a pump could do that but it would probably be caused by severe oil starvation causing cavitation. is the oil foamy, is the system noisy, is the lift circuit affected? if it is a pump problem it will affect all systems including steering to some degree. where are you connecting your guage. dead head the steering and see if the symptoms change.
  • Posted 11 Feb 2011 10:23
  • By toyzilla
  • joined 29 Mar'10 - 175 messages
  • Texas, United States
easier to ask forgiveness than to ask permission.
I'm still baffled on this one. Took the relief vavle out and everything seems in order. Adjusting the valve doesn't increase pressure. It's about 1500 max up to half throttle then it drops off to 900 at full throttle. This control valve has 3 electric solenoids. One shuts down the hydraulics when energized, I guess for the SAS. One needs to be energized to allow the forks to lower. And one on the tilt section that works the tilt self leveling feature, that shuts off when using that feature and the button is pushed and the forks are level. They all seem to be working fine.
Could the pump cause this problem? I've never seen a gear pump with the problem of pressure drop when the rpms are increased.
  • Posted 11 Feb 2011 05:22
  • By mrfixit
  • joined 11 Dec'08 - 1,434 messages
  • New York, United States
the releif valve on that truck is a double stem valve, the first section does lift and the second does tilt and auxiliary functions.
you can adjust the small stem without changing lift pressure.
  • Posted 8 Feb 2011 11:41
  • By toyzilla
  • joined 29 Mar'10 - 175 messages
  • Texas, United States
easier to ask forgiveness than to ask permission.

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