BGS technic 9069 Manual De Instrucciones página 5

VACUUM TEST
1. Use the supplied adaptors to connect gauge hose as close to the inlet manifold as possible,
ensure that the hose is not kinked. Should an engine have two inlet manifolds carry out separate
tests on each manifold.
2. Start engine, if required adjust idle speed to obtain a smooth tick over.
3. If the gauge needle remains steady with a reading between 17 and 22 inHg, the engine is in good
condition.
4. If the gauge drops back about 4 inHg on the dial, this would indicate sticky valves, disconnect the
vacuum hose and spray penetration oil into the manifold to lubricate the valves.
5. If the needle consistently drops, this would indicate that the valve clearances are too tight or that
a valve burnt out.
6. If the needle pulsates rapidly when the rpm is increased, this indicates that the valve springs may
be weak.
7. If the needle pulsates rapidly at idle and steadies out when the rpm is increased, indicates that
the valve guides are worn or loose.
8. If the needle is slow to drop back after the engine rpm has been increased several times in
succession, would indicate that the exhaust system may be partially blocked.
9. If the gauge indicates less than 10 inHg, this would indicate that the valve timing is late.
10. To check the choke, close the throttle and turn the engine over using the starter motor, the gauge
should rise quickly to 22 inHg. If the gauge remains at a low reading or 3 to 6 inHg then the
throttle may not be fully or there may be fully closed or there may be an air leak in the inlet
manifold.
11. Note: Gauge readings will vary with altitude, at sea level the approximate reading will be 19.5
inHg, for every 1000ft above sea level the vacuum gauge will drop by 1 inHg. For instance at
2000ft the reading will be 17.5 inHg.
FUEL PUMP VACUUM TEST (Mechanical fuel pumps only).
1. Disconnect the inlet pipe to the fuel pump and plug the hose to avoid spillage.
2. Connect the vacuum pipe to the inlet connection of the fuel pump.
3. Start the engine, if the gauge indicates approximately 10 inHg the pump is in good condition.
FUEL PUMP PRESSURE TEST (Mechanical fuel pumps only).
1. Disconnect the fuel pipe from the outlet of the fuel pump.
2. Connect the gauge hose to the outlet side of the fuel pump.
3. Start the engine, there should be enough fuel in the carburetor to allow the engine to run for
about two minutes.
4. Check the pressure reading against manufacturer's specifications for that model.
5. The fuel pump pressure should remain fairly constant for several minutes after the engine has
stopped. If pressure reduces quickly check the fuel pump diaphragm and seals for leaks.
CARBURETTOR TEST
Note: Ensure that the spark plugs, ignition timing and valve clearances are all correctly adjusted
before adjusting the carburetor.
1. Connect the gauge hose to the inlet manifold.
2. Start engine and allow to reach normal operating temperature. At idling speed the gauge should
have a steady reading between 17 and 22 inHg, if the needle varies between 14 and 22 inHg, this
indicates that the carburetor requires adjustment.
3. Adjust the carburetor as follows:
a) At idling speed adjust the mixture screw until the highest reading is obtained and the needle
is steady.
b) If a high speed adjustment is required, increase the engine speed to 2000 to 2500rpm and
adjust the mixture until the highest reading is obtained with a steady needle.
c) If the carburetor has a high and low speed setting adjust the high speed setting first.
Note: If the carburetor is worn, has blocked jets or incorrect jets fitted it may not be possible to adjust
the carburetor to its optimum.
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