Figure 3-9. Fuel pump removal and installation.

MEC 4320-240-15/3-9

Figure 3-9. Fuel pump removal and installation.

the proper power mixture for full throttle operation. Due

to wide open position when engine reaches normal

to variations in temperature or fuels it may be necessary

operating temperature.

to enrich this mixture by backing out the main jet

adjusting needle, a small amount at a time until good

(2) Low speed or idle adjustment. Set throttle or

acceleration is obtained.

governor control lever in slow idle position and adjust

throttle stop screw for the correct engine idle speed.

c. Removal. Refer to figure 3-10 and remove the

(On a new, stiff engine this speed must be slightly

carburetor.

higher than required for a thoroughly run-in engine.)

Turn adjustment needle (fig. 8-10) until engine begins to

d. Cleaning and inspection.

falter or roll from richness, then turn needle in the

opposite direction until the engine runs smoothly.

(1) Clean the outside of the carburetor with a

cloth dampened with cleaning solvent; wipe dry. Clean

Note: It is better that this adjustment be

all metal parts in an approved cleaning solvent; dry with

slightly too ric h than too lean.

clean, dry compressed air.

(3) Main jet adjustment. With the engine running

(2) Inspect the carburetor for damage; replace if

at governed speed under load, turn adjusting needle

damaged. Inspect all other metal parts for cracks,

(fig. 8-10) to the right, or clockwise, a little at a time until

dents, or other damage; replace if damaged. Inspect

the power drops appreciably. Then turn the needle to

the fuel line for cracks, wear, or deterioration; replace if

the left, or counterclockwise, until the engine picks up

damaged.

power and runs smoothly. This will give an economical

part throttle mixture, and, due to the economizer action,

3-11