Carburetor Disassembly; Carburetor Inspection - Tecumseh TM SERIES Technician's Handbook

CARBURETOR DISASSEMBLY

1. Note or mark the location and sequence of the
diaphragm(s), gasket(s), and the metering or pump
cover. Remove the screw(s), gaskets, and diaphragms.
2. Remove the idle mixture screw. On Tillotson model
HU carburetors, remove the plastic screw or brass
plug over the main mixture jet and remove the main
mixture jet if necessary for cleaning (diag. 3-11).
3. Use a 8-32 tap with the tapered flutes removed to turn
into the brass welch plug until it bottoms and begins
to turn the welch plug. Carefully pull the welch plug
from the carburetor body.
4. Note or mark the location and action of the throttle
and air vane, and choke shaft (if applicable). Remove
the screw holding the throttle or choke shutter to the
shaft. Remove the Torx T8 screw (use part # 670334)
holding the air vane to the throttle shaft if applicable.
Remove the clip screw, dust seal retaining clip, and
throttle shaft. On some older Walbro carburetors it is
necessary to remove the circlip on the end of the
throttle shaft to remove the shaft (diag. 3-11).
5. Remove the inlet needle valve, metering lever, and
metering lever spring by removing the retainer screw
on the pivot pin (diag. 3-11).
6. Remove the fuel inlet screen and check valve screen
using an "O" ring pick. Remove all welch plugs using
a sharpened small chisel. Drive the sharpened chisel
into the welch plug, push down on the chisel to pry the
welch plug out of position. Be careful not to damage
the carburetor body (diag. 3-12).
7. On Walbro carburetors, the fuel inlet fitting can be
removed with a pliers using a twisting and pulling
motion. Do not re-use the old fuel fitting. The fuel fitting
on Tillotson carburetors is not replaceable. Do not
remove. Carburetor cleaner will not affect this fitting.
8. Clean all metallic parts in carburetor cleaner. Do not
exceed 30 minutes soak time. Blow out all fuel
passages with compressed air. Do not use tag wire to
clean the orifice in the main mixture seat assembly.
The main mixture seat assembly contains a teflon
disc check valve. If the disc is damaged with tag wire,
the carburetor will not function properly.

CARBURETOR INSPECTION

Visually examine the throttle lever shaft and choke shaft
for wear at the bearing points in the carburetor body.
Inspect the pump and metering diaphragms for hardness,
fuel contamination, holes or tearing in the diaphragm.
Pump diaphragm flapper valves should appear flat with no
curling. Check the inlet screen and check valve screen for
contamination. Check the atmospheric vent hole in the
metering cover and clean if necessary.
Check the inlet needle for wear on the taper portion of the
needle. Replace as necessary.
20
Dust Seal Retainer
Metering Lever
Dust Seal
Metering Lever Screw
Metering Lever Spring
Dust Seal
Inlet Valve
Needle
Fuel Inlet
Screen
Dust Seal
Dust Seal Washer
Throttle Shaft Return Spring
Note: Do not allow chisel point to strike
carburetor body or channel reducer
Pry out
plug
Pierce plug with tip
Small Chisel
Metering Lever Pin
Tension Spring
Idle Mixture
Screw
Welch Plug
Main Mixture Jet
Throttle
Shutter
Throttle
Screw
Shutter
Throttle Shaft
Welch Plug
1/8"
3-11
3-12