Stihl TS 420 - 12.7.2 Removal and installation; 12.7.3 Manual fuel pump

95TS 410, TS 420
12.7 Tank vent
12.7.1 Testing
If problems develop in the
carburetor or fuel supply, the tank
vent must always also be tested and
replaced if necessary. Correct
functioning is determined by testing
the fuel tank under vacuum or at
gauge pressure via the fuel hose.
– Open the filler cap and drain the
fuel tank in accordance with
regulations, b 1.
– Close the filler cap.
– Remove the air filter, b 12.1.
– Remove the carburetor, b 12.2.
: Disconnect the fuel hose (1) of
the manual fuel pump from the
connector (arrow).
: Connect a separate fuel hose (1)
to the connector (arrow) and
seal it.
1
370RA416 TG370RA417 TG
1
: Push the double nipple (1)
0000 855 9200 into the fuel hose
(arrow).
Testing with negative pressure
: Slide ring (1) to the left and
connect the pump (2)
0000 850 1300 to the double
nipple (arrow). Build up a vacuum
in the fuel tank.
Pressure is equalized via the tank
vent. A negative pressure must not
build up inside the tank.
– Clean the area around the tank
vent.
– Replace the tank or tank vent if
necessary, b 12.7.2 or b 12.9.
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370RA418 TG
1
370RA419 TG
2
Testing with gauge pressure
: Slide ring (1) to the right and
connect the pump (2)
0000 850 1300 to the double
nipple (arrow). Build up gauge
pressure in the tank.
– Actuate the pump until the
pressure gauge shows a
pressure of 0.3 bar. If this
pressure remains constant for at
least 20 seconds, the tank and
tank vent are airtight. If the
pressure drops, the leak must be
located and the defective part
replaced.
– Disconnect the separate fuel
hose.
: Connect the fuel hose (1) of the
manual fuel pump to the
connector (arrow).
– Reassemble remaining parts in
reverse order.
1
370RA420 TG
2
1
370RA421 TG