33
FUEL SYSTEM
CS-370ES
CS-420ES
2K253A
4-13 Replacing Welch plug
If engine does not run smoothly even after
readjusting carburetor and inspecting carburetor
parts, inspect low speed ports on carburetor as
follows:
1. Remove metering lever and related parts to
protect them from damage.
2. To remove Welch plug (A), punch the remover
tool (B) through Welch plug at low angle and pry it
out.
NOTE: Remover tool (B) is included in Welch plug
tool (Part number: 500-500).
3. Clean low speed ports with compressed air.
4. Place a new Welch plug over the opening and
gently tap it until flush using welch plug installer (C).
5. Install all removed parts to carburetor body.
4-14 Inspecting diaphragm
1. Inspect metering diaphragm (A) for hardening,
distortion, or pin hole. Replace as required.
2. Remove pump cover (F), pump diaphragm (D)
and pump gasket (E).
3. Inspect pump diaphragm (D) and replace if
hardened or curled at valve tabs.
4. Inspect metering gasket (B) and pump gasket (E)
and replace if defective.
5. Inspect inlet screen (C) if blocked, remove and
clean it, or replace.
6. Clean fuel passages in carburetor body with
compressed air.
NOTE: Before cleaning metering side with
compressed air, turn “H” needle clockwise until lightly
seated and remove inlet needle valve. Otherwise,
main nozzle check valve and inlet needle valve
spring may be damaged by the compressed air.
A
B
C
A
B
D
E
F
C
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