Section VI. RADIO INTERFERENCE SUPPRESSION

Probable Cause

Possible Remedy

Probable Cause

Possible Remedy

Air leak in suction line ............ Tighten connections.

Total head too high ................ Rearrange system to

reduce

elevation

Check for pinholes.

Suction lift too high ................ Move pump closer

between

point

delivery and supply.

supply.

Section VI. RADIO INTERFERENCE SUPPRESSION

3-25. Definitions

3-27. Interference Suppression Components

a. Interference. The term "interference" as used in

a. Primary Suppression Components. The primary

this manual applies to electrical disturbances in the

suppression components are those whose primary

radio-frequency range which are generated by the pump

function is to suppress radio interference.

engine and which may interfere with the proper

b. Secondary Suppression Components. These

operation of radio receivers or other electronic

components have radio interference suppression

equipment.

functions which are incidental and/or secondary to their

b. Interference Suppression. The term "interference

primary function.

suppression" as used in this manual applies to the

3-28. Replacement of Suppression Components

methods used to eliminate or effectively reduce

a. Shielded Ignition Leads. Refer to (para -47) and

interference generated by the pump engine.

replace the shielded ignition leads.

3-26.

General Methods to Attain Proper

b. Ground Strap. The engine has two ground straps,

Suppression

one on the magneto and one on voltage regulator.

Essentially, suppression is attained by providing a low-

3-29. Testing of Radio Interference Suppression

resistance path to ground for stray high-frequency

Components

currents. The methods used to attain suppression

include shielding the ignition and high-frequency wires,

Test the capacitors for leaks and shorts on a capacitor

and grounding the frame with bonding straps, and using

tester; replace defective capacitors. If test equipment is

capacitors and resistors.

not available and interference is indicated, isolate cause

by the trial and error method of replacing each capacitor

Note. Do not pull on cable or twist braided

in turn until the cause of interference is located and

shielding. Gently work cable from side to side and

eliminated.

free the rubber seal. Do not use sharp metal tools

to Install rubber seals .

Section VII. FUEL SYSTEM

3-30. General

b. Removal. Refer to figure 3-9 and remove the fuel

pump.

The purpose of the fuel system is to store, convey, mix

fuel with air, and then vaporize and introduce the

c. installation. Refer to figure 8-9 and install the fuel

mixture into the engine. Fuel is stored in the gasoline

pump.

tank. It is filtered and flows to the carburetor under the

3-32. Carburetor

pressure of a fuel pump. The carburetor mixes the fuel

a. General. The carburetor mixes air and fuel and

with the proper proportions of air and at the same time

introduces the mixture to the intake manifold.

breaks it into very fine spray particles. This atomized

spray changes to vapor as it travels through the heated

b. Adjustments.

intake manifold to the combustion chamber.

(1) Preliminary adjustments. Set throttle stop screw

3-31. Fuel Pump

(fig. 3-10) so that throttle valve is open slightly. Make

certain that fuel supply to carburetor is open. Close

a. General. The fuel pump transfers the fuel from the

choke valve. Start engine and partially release choke.

fuel tank to the carburetor.

Return choke

3-10