Fill the supply tank in the injector tester
with clean injector test oil J 26400. Open
the valve in the fuel supply line. Place
the test block on the injector locating
plate and secure the block in place with
the fuel inlet connector clamp. Operate
the pump handle until all of the air is out
of the test block, then clamp the fuel
outlet connector onto the test block.
Break the connection at the gauge and
operate the pump handle until all of the
air bubbles in the fuel system disappear.
Tighten the connection at the gauge.
Operate the pump handle to pressurize
the tester fuel system to 2400-2500 psi
(16,536-17,255 kPa). Close the valve on
the fuel supply line. After a slight ini-
tial drop, the pressure should remain
steady. This indicates that the injector
test is operating properly. Open the fu-
e l valve and remove the test block.
Figure 11C-74. Checking Fuel Output
If there is a leak in the test fuel system,
3. Counter Improperly Set: The counter
it
will
be
indicated
by
a
drop
in
should be set to divert the injector out-
pressure. The leak must be located,
put at 1,000 strokes.
corrected and the tester rechecked be-
fore checking an injector.
This should not be confused with counter
overrun that will vary from 2 to 6 digits,
Occasionally dirt will get into the pump
depending upon internal friction. The
check valve in the tester, resulting in
fuel diversion is accomplished electrically
internal pump valve leakage and the ina-
and will occur at 1,000 strokes (if prop-
bility to build up pressure in the tester
erly set) although the counter may
fuel system. Pump valve leakage must
overrun several digits.
be corrected before an injector can be
properly tested.
4. Test Oil: A special test oil is supplied
with the calibrator and should always be
When the above occurs, loosen the fuel
used. 1 regular diesel fuel oil (or any
inlet connector clamp and operate the
other fluid) is used, variations are usu-
tester pump handle in an attempt to
ally noted because of the effect of the oil
purge the dirt from the pump check
on the solenoid valve and other parts.
valve. A few quick strokes of the pump
handle will usually correct a dirt condi-
The fuel oil introduced into the test oil
tion. Otherwise, the pump check valve
when the fuel injector IS placed in the
must be removed, lapped and cleaned or
calibrator for a calibration check contam-
replaced (J 9787). The pump check
inates the test oil. Therefore, it is im-
valve must be replaced on tester J 23010.
portant that the test oil and test oil filter
be changed every six months, or sooner
If an injector tester supply or gauge line
if required.
is damaged or broken, install a new re-
placement line (available from the tester
I n a d d i t i o n , other malfunctions such as a
manufacturer). Do not shorten the old
slipping drive belt, low level of test oil,
lines or the volume of test oil will be al-
a clogged filter, a defective pump or
tered sufficiently to give an inaccurate
leaking line connections could cause bad
valve holding pressure test.
A frequent check should be
readings.
made
for
any
of
these
tell-tale
If it is suspected that the lines have
conditions.
been altered, by shortening or replacing
with a longer line, check the accuracy of
CHECK INJECTOR TESTER J 23010. The
the tester with a master injector on
injector tester should be checked month-
which the pressure holding time is
ly to be sure that it is operating proper-
known. If the pressure holding time
The following check can be made
does not agree with that recorded for the
very quickly using test block J 9787-49.
master injector, replace the lines.
11C-46
