GPV13 User
Manual ◄ 17
TESTING & TROUBLESHOOTING
GENERAL
Tests and adjustments should be performed periodically
to ensure the power unit is operating at maximum ef-
ficiency. Stanley Circuit Tester (Part Number 04182) is
recommended. This tester can be used to isolate prob
-
lems in both the engine and hydraulic system prior to
any power unit disassembly.
TESTING THE HYDRAULIC CIRCUIT
The following tests can be performed to ensure that the
hydraulic pump is supplying the correct flow and pres-
sure and that the system relief valve is operating prop
-
erly.
During these tests, make sure the engine is warm and
operating smoothly. If test results are not as specified,
refer to the troubleshooting table in this section for pos
-
sible causes.
TESTING THE 5 GPM HTMA TYPE 1 OR 8
GPM HTMA TYPE II CIRCUIT
To test the circuit, proceed as follows:
1. Set the throttle control lever to the far left or full throt
-
tle position.
2.
Connect the Stanley Circuit Tester across the hose
ends (where the tool would normally be connected).
3.
Fully open the tester restrictor valve (counterclock-
wise).
4.
Start the engine and allow it to run until warm.
5.
With the engine at full operating speed, the test
flow gauge should read 4–6 gpm/15–23 lpm on
GPV135H02 or 7-9 gpm/26-34 lpm on GPV138B02.
6.
Slowly turn the restrictor valve clockwise while watch-
ing the pressure gauge. The flow rate should stay at
4–6 gpm/15–23 lpm as the pressure gauge reaches
1900
–
2000 psi/131
–
138 bar on GPV135H02 or 7–9
gpm/26–34 lpm as the pressure gauge reaches
1900
–
2000 psi/131
–
138 bar on GPV138B02.
7. At 1900
–
2000 psi/131
–
138 bar, the relief valve
should begin to open. The pressure at which the re-
lief valve just begins to open is commonly referred
to as the “cracking pressure”. At the “cracking pres-
sure,” the flow rate should start to drop because the
relief valve is allowing fluid to bypass to the hydrau-
lic reservoir. The “cracking pressure” is preset at the
factory and if it is not within the above range, the
relief valve must be re-set as follows:
a. The relief valve is located behind the dash pan
-
el in the valve manifold assembly. Use an open
end or box end wrench to loosen the nut on the
relief valve.
b.
Use an Allen wrench to adjust the relief valve.
Turn clockwise to raise the pressure and coun-
terclockwise to reduce the pressure.
c. Tighten the nut and retest.
