Fuel tank positive and negative ventilation system - RA4700FLH0030X(47-0030)

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

A. All models

Fig 1: Function Of Fuel Tank Positive And Negative Ventilation System Components (All Models)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Cap

The fuel evaporation gases are able to escape through the cap at a pressure of 100-300 mbar. This only occurs, however, if, for example, the vent pipe from the fuel tank is blocked as a result of crimping or improper routing. If the system is operating properly, a pressure of up to 50 mbar may occur in the fuel tank.

B. Model 124

Fig 2: Function Of Fuel Tank Positive And Negative Ventilation System Components (Model 124)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The vent system consists of a central pipe (54) with interruption vessels (54/1) at the ends. The interruption vessels (54/1) prevent the fuel escaping along the vent line (64). The vent line (64) runs from the central pipe through the vent valve (51) to the activated charcoal filter (52). Air is admitted to the activated charcoal filter (52) and fuel tank (50) from the engine compartment through the cup seal (52/1).

C. Models 129, 140

Fig 3: Function Of Fuel Tank Positive And Negative Ventilation System Components (Model 129, 140)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

The vent system consists of a central pipe (54) with interruption vessels (54/1) at the ends. The interruption vessels (54/1) prevent the fuel escaping along the vent pipe (64). The vent pipe runs from the central pipe (64) through the vent valve (51) to the activated charcoal filter (52).

Model 129

Air is admitted to the activated charcoal filter (52) and fuel tank (50) from the left front of the side member.

Model 140

Air is admitted to the activated charcoal filter (52) and fuel tank (50) from the rear left wheelhouse.

D. Model 140 with through-loading facility

Fig 4: Function Of Fuel Tank Positive And Negative Ventilation System Components (Model 140 With Through-Loading Facility)

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

On vehicles with through-loading facility, the fuel tank (50) is lower in the middle and the expansion tank (55) is located to the outside.