5.3
Section 5
Fuel System and Governor
5
Repair
Nylon-bodied fuel pumps are not serviceable and must
be replaced when faulty. Replacement pumps are
available in kits that include the pump and mounting
gasket.
Removal
1. Disconnect the fuel lines from the inlet and outlet
fi ttings of the pump.
2. Remove the hex. fl ange screws, fuel pump, and
gasket.
3. If necessary, remove the fi ttings from the pump
body.
Installation
1. Fittings - Apply a small amount of Permatex
®
Aviation Perm-A-Gasket (or equivalent) gasoline
resistant thread sealant to the threads of the
fi ttings. Turn the fi ttings into the pump 5 full
turns; continue turning the fi ttings in the same
direction until the desired position is reached.
2. Install new gasket, fuel pump, and hex. fl ange
screws.
NOTE: Make sure the fuel pump lever is
positioned to the right of the camshaft
(when looking at fuel pump mounting
pad). Damage to the fuel pump, and
severe engine damage, could result if
the lever is positioned to the left of the
camshaft.
3. Torque the hex. fl ange screws as follows:
Into new as-cast hole–9.0 N·m (80 in. lb.).
Into used hole–4.2-5.1 N·m (37-45 in. lb.).
4. Connect the fuel lines to the inlet and outlet
fi ttings.
Carburetor (Gasoline)
These engines are equipped with one of two basic
types of fi xed main jet carburetors–Walbro or Nikki.
See Figure 5-3.
Walbro carburetors have a low idle speed screw and
a low idle fuel adjusting needle. Nikki carburetors only
have a low idle speed screw. Certifi ed carburetors
will have fi xed idle fuel or a limiter cap on the idle fuel
adjusting needle.
Figure 5-2. Installing Fuel Pump.
Hex. Flange Screw (2)
Fuel Fittings
Gasket
Fuel Pump
Figure 5-3. Carburetor Adjustment.
WARNING: Explosive Fuel!
Gasoline is extremely fl ammable and its vapors can
explode if ignited. Store gasoline only in approved
containers, in well ventilated, unoccupied buildings,
away from sparks or fl ames. Do not fi ll the fuel tank
while the engine is hot or running, since spilled fuel
could ignite if it comes in contact with hot parts or
sparks from ignition. Do not start the engine near
spilled fuel. Never use gasoline as a cleaning agent.
Walbro
Nikki
Low Idle Speed
Adjustment Screw
Low Idle Fuel
Adjustment Needle
Low Idle Speed
Adjustment Screw
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