The engine power supply system is forced, with fuel supply by a diaphragm-type fuel pump

The fuel for the engine is motor gasoline with an octane rating of at least 76 (GOST 2084-67).

The use of lower quality motor gasoline may cause abnormal engine operation (detonation, increased carbon deposits, increased fuel consumption, burnout of gaskets and cylinder heads, etc.).

ZIL-131 power system diagram

The main and secondary fuel tanks, with a capacity of 170 liters each, are located on both sides of the frame under the loading platform.

The filler necks of the tanks are closed with hermetic hinged caps with quick-release clamps (Fig. 2).

ZIL-131 tank plug

The right fuel tank is equipped with a valve box (Fig. 3) with automatically operating valves (inlet and outlet), connecting the fuel tank cavity with the atmosphere in case of an increase or decrease in the internal pressure in the tank.

The left fuel tank is connected to the right fuel tank by an air tube.

When the vacuum in the tank is 0.016-0.034 kg/cm2, the inlet valve 3 of the valve box opens and the tanks communicate with the surrounding air.

When the pressure in the tanks rises by 0.11-0.18 kg/cm2, the outlet valve 4 opens

Such a valve box arrangement ensures pressure equalization in the tanks and reduces fuel loss from evaporation.

The valve is connected to an air tube, brought out above the level of a given ford and fixed on the rear wall of the cab.

ZIL-131 fuel tank valve box

If, after filling the fuel tanks, a long stop is expected, it is recommended not to fill the right tank completely in order to avoid fuel leakage through the valve when the outside temperature rises.

There is a hole 5 in the lever of the quick-release plug clamp (see Fig. 3), which coincides with the hole in the neck bracket when the plug is closed.

When driving off-road, to eliminate cases of spontaneous opening of plugs as a result of hooks in the holes of plugs and neck brackets, it is necessary to hang a lock or insert a bolt with a nut.

During operation, it is necessary to periodically check and tighten the fastening of fuel tanks and brackets, drain sediment through the drain plugs and flush the tanks, clean and flush the valves on the additional tank and blow out the pipes connecting the main and additional tanks.

If both tanks are full, fuel should be consumed first from the main (left) tank.

It is necessary to use fuel from the additional (right) tank only if it is impossible to fill the main tank with fuel.

Switch the tanks with a tap mounted on the bracket of the main tank sump filter.

The valve has three positions: the main tank is on, the additional tank (right) is on, and the valve is closed (see Fig. 1).

The fuel level in the tanks is controlled by a level indicator mounted on the instrument panel.

The fuel gauge can be connected to any tank, regardless of which tank the fuel is being used from.

The switch for the fuel gauge is installed on the front shield of the cab. The right position corresponds to the connection of the right tank, the left position of the left tank.