Fuel supply
Air Top Evo 3900 / Air Top Evo 5500
66
7.1.
Vehicles with carburettor engines
The fuel may only be extracted using the special Webasto fuel extractor
(see Figure 10) as close to the tank as possible. The connect may be made
in either the supply or return line, in which case the return line must lead
almost to the base of the tank (see Figure 11).
The fuel extractor must be fitted in such a way that any air or gas bubbles
are automatically discharged towards the tank (see Figure 10).
The fuel extractor should not be located near the engine, as gas bubbles
may form in the lines on account of heat radiated from the engine. This
may cause problems during combustion.
7.2.
Vehicles with injection engines
When installing the heater in a vehicle with fuel injection system, it is im-
portant to establish whether the vehicles fuel pump is located inside or
outside the tank.
If the fuel pump is located inside the tank, fuel can only be extracted from
the return line using the Webasto fuel extractor (see Figure 10), in which
case it must be checked to ensure that the fuel return pipe in the tank ter-
minates near the bottom of the fuel tank (see Figure 11 for details of the
minimum distance from the bottom of the tank). If this is not the case We-
basto fuel extractor (see Figure 11, 12 and 13) may be used.
If the fuel pump is installed outside the tank, the fuel connection may also
be made between the tank and the fuel pump, again using only the We-
basto fuel extractor (see Figure 10).
7.3.
Vehicles with diesel engines
The fuel must be taken from the vehicle fuel tank or from a separate tank
(see Figs. 11, 12 and 13). This separate fuel pick-up precludes any effect of
pressure.
NOTE:
The tank fitting must be made from metal!
7.4.
Fuel lines
Only steel, copper and plastic lines of plasticised, light and temperature-
stabilised PA 11 or PA 12 (e.g. Mecanyl RWTL) pursuant to DIN 73378 may
be used for the fuel lines.
Since the lines normally cannot be routed with a constant rising gradient,
the internal diameter must not be allowed to exceed a certain size. Air or
gas bubbles will accumulate in lines with an internal diameter of more than
4 mm and these will cause malfunctions whilst the heater is operating if
Fig. 10
Webasto fuel extractor
to metering pump
to engine
from tank
Installation_Instructions_Air_Top_Evo_3900_5500_de_en_nl.book Page 66 Wednesday, November 3, 2010 11:58 AM
