Lesson 1/Learning Event 1
Some tanks have baffle plates. Baffle plates strengthen the tank and reduce the sloshing of the fuel. On
rough roads, fuel sloshing in the tank creates problems. First, fuel evaporates rapidly if it sloshes around in a
container, especially in hot weather. Also, the sloshing fuel generates static electricity, and a spark in the fuel
tank could cause an explosion. Baffles control the liquid and still allow the fuel to move freely through
An outlet pipe, also called the pickup tube, is installed through the top or the side of the fuel tank. The
bottom tip of the pipe is positioned about half an inch above the bottom of the tank; this reduces the
chances of picking up water or trash. (Sometimes the tip end of the pipe is shielded by a screen or filter to
keep trash from entering.)
A vent tube is necessary so that outside air can fill up space left by the fuel drawn from the tank. The vent
also allows air in the tank to escape when the fuel in the tank expands. (Fuel will always expand when the
vehicle is standing in the hot sun.) On most military vehicles, the vent is a leakproof tube that connects the
tank to the carburetor air cleaner. Sometimes the fuel pickup and vent tubes are placed close together. (The
vent tube is smaller than the fuel pickup tube.)
A fuel gage sending unit is connected by an electrical wire to the fuel gage on the vehicle instrument panel.
This sending unit shows the level of fuel in the tank.
MAIN FUEL LINE
Fuel from the tank is delivered to the engine by the main fuel line. This line is usually made of copper or
steel tubing and is secured to the frame by clamps or clips to reduce the chances of breakage. At the engine
compartment, a flexible hose connects the main fuel line with the filter or the fuel pump. Without this
flexible hose, the main fuel line would be broken by vibration between the engine and the frame.
Filters are used to remove trash that could hurt engine performance or clog fuel passages.
The carburetor contains many small passages that can be easily clogged by trash. For this reason, fuel filters
are located between the fuel tank outlet pipe and the carburetor. Some vehicles have more than one filter.