Section 10 FUEL SYSTEM
Subsection 04 (CARBURETOR)
SMR2003-032_10_04A.FM 10-04-3
CLEANING
The carburetor exterior surfaces should be cleaned
with a general solvent and dried with compressed
air before disassembly.
CAUTION: Be careful at carburetor cleaning not
to remove paint. Paint removal will cause carbu-
retor to rust very rapidly. Repaint if necessary.
Carburetor body and jets should be cleaned with
a carburetor cleaner. Follow manufacturer’s in-
structions.
CAUTION: Heavy duty carburetor cleaner may
be harmful to the rubber parts, O-rings, etc.
Therefore, it is recommended to remove these
parts prior to cleaning.
Inspect O-rings, diaphragms and gaskets.
DISASSEMBLY AND INSPECTION
Inspect parts for corrosion damage (shaft, throttle
plate, spring, screw, check valve housing, etc.).
Needle Valve
Inspect needle valve tip for a grooved condition. If
worn, needle and seat must be replaced as a
matched set.
Low Speed Screw
Check tip of low speed screw no. 2 for a grooved
condition. Replace if necessary.
Diaphragm
Pump Diaphragm Leak Test
Using a suitable pump gauge tester, perform the
following test proceeding as follows:
– Install pump gauge tester (P/N 295 000 114) on
pulse nipple.
– Pump tester until it reaches 28 kPa (4 PSI).
TYPICAL
1. Pump gauge tester
2. Install on pulse nipple
Diaphragm must stand pressure for 10 seconds.
If pressure drops, replace diaphragm no. 3.
Fuel Pump Valve
Check fuel pump valve operation as follows:
Connect a clean plastic tubing to the inlet nipple of the
fuel pump body no. 4 and alternately apply pressure
and vacuum with the mouth. The inlet valve should
release with pressure and hold under vacuum.
TYPICAL
1. Fuel outlet nipple
2. Pulse nipple
3. Inlet nipple
Repeat the same procedure at the outlet nipple of
the fuel pump body no. 4. This time the outlet
valve should hold with pressure and release under
vacuum.
Inspect valves. The pumping area should be free
of holes, tears or imperfections. Replace as needed.
WARNING
Solvent with a low flash point such as gaso-
line, naphtha, benzol, etc., should not be used
as they are flammable and explosive.
WARNING
Some fuel may be present in fuel pump. Be
careful not to swallow fuel when under vacuum.
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