Pontiac FIREBIRD 1972 Service Manual page 291

REAR SUSPENSION 4- 5
<
TROUBLE DIAGNOSIS (Continued)
9. Satisfactory build-up indicates system problem to be
in the control section. However, again observe the
test gage for evidence of an air leak and proceed
accordingly.
PRESSURE REGULATOR TEST
Performance test the regulator with a known good com-
pressor on the car.
Deflate system through service valve and disconnect
line at pressure regulator valve.
Install test gage on regulator valve high pressure fit-
ting (Fig. 4-1).
Inflate system through service valve to maximum
available pressure (Fig. 4-2).
NOTE: I f available pressure is less than 140psi
start engine to build-up reservoir to this pres-
sure.
Regulated pressure should build-up to and hold
steady at 100-130 psi on test gage.
Check regulated pressure by momentarily (not more
than one second) depressing valve core on test gage
and observe gage reading.
If regulated pressure now reads less than 100 psi,
replace regulator assembly.
If regulated pressure exceeds 130 psi, replace regula-
tor assembly.
HEIGHT CONTROL VALVE TEST--ON CAR
EXHAUST (SUPERLIFTS INFLATED)
Disconnect overtravel lever from link.
Hold lever down in exhaust position until Superlifts
deflate or for a minimum of 15 seconds.
If Superlifts deflate, perform Intake Check.
If Superlifts do not deflate, remove exhaust adapter
from control valve and hold lever down as in Step 2.
Replace adapter, "0" ring and filter if this deflates
Superlifts.
Replace control valve if none of the above steps cor-
rects problem.
INTAKE (RESERVOIR PRESSURE 125 PSI
MINIMUM)
1. Disconnect overtravel lever from link.
2. Hold lever up in intake position until Superlifts in-
flate or for a minimum of 15 seconds.
3. If Superlifts inflate and hold, proceed to TIME
DELAY CHECK.
4. If Superlifts inflate and then leak down, perform leak
test on lines and fittings and then on Superlifts. Also
check and, if necessary, replace HCV intake and ex-
haust screens and "0" rings. If Superlifts still do not
inflate, perform leak test on valve. Repair as in-
dicated and proceed to TIME DELAY CHECK.
TIME DELAY CHECK
1. Disconnect overtravel lever from link.
2. Disconnect lines at Superlift and intake port.
3. connect test gage to intake valve port and open air
pressure (95 psi). Move overtravel lever approxi-
mately 1" down from neutral position, as measured
from end of lever.
4: Quickly move overtravel lever upward 2". At the
same time, begin timing number of seconds before air
starts to escape from Superlift port. This delay should
be from 4-1 8 seconds. Repeat check. This will check
the air intake time delay. Proceed with check to de-
Fig. 4-2 Filling System through Service Valve
termine air exhaust time delay.