CLAS B.LINE AC 0550BL Mode D'emploi page 17

HU 0014BL
METAL TRANSFER PUMP
4. SYSTÈMES DE CARBURANT : Test des pompes à carburant mécaniques
The AC 0550BL can be used to evaluate the condition of a mechanical fuel pump by testing
the vacuum it is capable of creating. Locate and remove the suction line from the pump.
Connect the pump of the AC 0550BL to the suction port of the fuel pump, start and idle
the engine. The vacuum reading to be observed varies slightly between makes and models,
but as a general rule of thumb, a vacuum of approximately 15 inHg should be created. This
value should also be maintained for about 1 minute after the engine is shut off. If this vacuum
reading is not obtained, or if the vacuum decreases immediately after the engine is shut off,
the fuel pump should be overhauled or replaced.
Carburettors
There are many types of vacuum control systems used on carburettors. Using this kit allows
you to test these systems quickly and accurately. Below are two examples of tests that can
be performed.
Example 1. Testing a choke rupture diaphragm.
With the engine at normal operating temperature but not running, disconnect the vacuum
line to the diaphragm module. Connect the fluid (fig.4) and apply approximately 15 inHg of
vacuum and wait 30 seconds. Do not observe a drop in gauge reading. With the vacuum still
applied, make sure the throttle butterfly is pulled to the fully open position.
Example 2. Carburetor secondary barrel test under vacuum.
With the engine at normal operating temperature but not running, remove the vacuum line
from the secondary diaphragm module. Connect the pump (fig.5), keep the throttle and
secondary air valve valves open. Operate the hand pump while observing the free and easy
opening of the secondary air valve throttle.
Fuel Injection Pressure Regulator Test
The pressure of the multipoint fuel injection manifold must vary according to engine load
variations and fuel requirements. This is done using a vacuum regulator which is connected
to the vacuum in the engine manifold to detect variable loads. To test the fuel injection rail
pressure, a pressure gauge is attached to the rail, and then engine loads must be created to
vary the vacuum in the engine manifold. Simply remove and block the vacuum supply line to
the pressure regulator, connect and operate the fluid vacuum pump (fig.6) to simulate the
vacuum pressures according to the manufacturer's specifications and note the variation in
the fuel pressure reading.
Testing of exhaust gas recirculation (EGR) valves
Start the engine and idle it until normal operating temperature is reached. Remove the vacuum
line from the EGR valve and attach the fluid vacuum test kit (fig.7). Operate the hand pump
to apply a vacuum of approximately 15 inHg. If the EGR valve is operating properly, engine
idle will become uneven. If the idle speed remains unchanged, the valve may be seized in the
closed position. If the vacuum is not maintained, the valve diaphragm will fail.