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EXAMPLE 1.
Testing a Choke Break Diaphragm. With the engine at normal operating temperature but not running, disconnect the vacuum line to
the diaphragm module. Connect the VS403.V3 vacuum tester (fig.5) and apply approximately15 inHg of vacuum and wait for
30 seconds. No drop in gauge reading should be observed. With the vacuum still applied ensure that the choke butterfly is pulled to the
fully open position.
fig.5
fig.6
EXAMPLE 2.
Testing Vacuum Operated Carburettor Secondary Barrel. With the engine at normal operating temperature but not running, remove the
vacuum line from the secondary diaphragm module. Connect the VS403.V3 vacuum tester (fig.6), hold the throttle and secondary air
valve flaps open. Operate the hand pump whilst observing free and easy opening of the secondary throttle butterfly.
TESTING FUEL INJECTION PRESSURE REGULATOR
Multi-point fuel injection rail pressure must vary to suit changing engine loads and fuel delivery requirements. This is done using a
vacuum operated regulator which is connected to the engine manifold vacuum to sense the varying loads. To test the fuel rail pressure,
a gauge is attached to the rail, then engine loads must be created to vary engine manifold vacuum. Simply remove and block off the
vacuum supply line to the pressure regulator, connect and operate the VS403.V3 vacuum pump (fig.7) to simulate vacuum pressures in
accordance with the manufacturer's specifications and note variation in fuel pressure reading.
TESTING EMISSION CONTROL EXHAUST GAS RECIRCULATION VALVES (EGR)
Start engine and run at idle until normal operating temperature is reached. Remove the vacuum line from the EGR valve and attach
the VS403.V3 vacuum tester kit (fig.8). Operate the hand pump to apply approximately 15 inHg of vacuum. If the EGR Valve is working
correctly the engine idle will become rough. If the idle remains unchanged the valve is possibly seized in the closed position. If the
vacuum is not held,the diaphragm in the valve has failed.
fig.8
fig.7
TESTING ONE-WAY VALVES
5.6.
Many vacuum operated circuits use in-line one-way valves to apply vacuum in one direction only. To test the function of the valve
remove it from the circuit. Attach the VS403.V3 vacuum tester (fig.9) and operate pump to apply vacuum. In one direction the valve
should hold vacuum and in the opposite direction it should not.
fig.9
fig.10
Original Language Version
VS403.V3
Issue: 4 (H,F) 17/05/23
© Jack Sealey Limited
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