The 791-682039 Fuel Filter and Line, filters the fuel in the tank as it is forced into the carburetor up by means of the primer bulb.

To install.
Remove retainer ring from fuel line.
Insert fuel line thru gas cap opening.
Thread fuel line thru hole in bottom of the fuel tank.
Pull fuel line thru to firmly seat against inside tank wall.
Put retainer ring on fuel line,hold line and press ring firmly against the out side of the fuel tank wall.
Then attach fuel line to correct line on the carburetor.

The filter will at sometime get clogged with dirt and debris that has collected in the fuel tank, and will have to be replaced.

The primer hose is inserted into the fuel tank then connected to the Primer.
By pressing on the primmer a few times this assembly fills the carburetor with fuel.
When the carburetor has enough fuel in it, the excess fuel is forced back into the the tank through the fuel return line.

After time the primer hose will become brittle and crack and have to be replaced.
The primer will also lose its elasticity, and may also crack and not be able to suck up the fuel into the carburetor.
And will have to be replaced.

The purpose of the 791-181086 Fuel Return Tube is to return the excess fuel back into the fuel tank, after the primer bulb has been pressed and has primed the carburetor to start.

After time the Fuel Return Line will become brittle and crack and will need to be replaced.

This is a genuine OEM replacement part, it is sold individually.
The purpose of the Fuel Pick--Up Line with Filter is to provide fuel into the carburetor via the primer bulb.
The filter is situated inside the fuel tank,with the fuel line extending through an existing hole in the fuel tank.
It is then connected to the primer bulb which will purge the air out of the carburetor.
By pressing the primmer bulb it will fill the carburetor with fuel, once it is full the excess fuel will be forced back into the tank through the fuel return line.

Over time the fuel filter will be come clogged with debris and will have to be changed.

This is an OEM replacement part and is sold individually.
Its propose is to deliver an electric current from an ignition system to the combustion chamber of a gas fueled engine.
It will ignite the air fuel mixture by the spark.
Spark Plugs will usually have to gapped to the manufactures specifications found in the owners manual.

Over time a Spark Plug will become fouled because the air/fuel ratio may be set wrong,worn piston rings, carbon build up and other factors.
It is better to replace a fouled spark plug, rather then trying to clean it.

A carburetor basically consists of an open pipe through which the air passes into the inlet manifold of the engine.
The pipe is in the form of a Venturi: it narrows in section and then widens again, causing the airflow to increase in speed in the narrowest part.
Below the Venturi is a butterfly valve called the throttle valve — a rotating disc that can be turned end-on to the airflow, so as to hardly restrict the flow at all, or can be rotated so that it (almost) completely blocks the flow of air.
This valve controls the flow of air through the carburetor throat and thus the quantity of air/fuel mixture the system will deliver, thereby regulating engine power and speed. The throttle is connected, usually through a cable or a mechanical linkage of rods and joints.

Fuel is introduced into the air stream through small holes at the narrowest part of the Venturi and at other places where pressure will be lowered when not running on full throttle.