Webasto Air Top 3500 Installation Instructions Manual page 10

Visit www.butlertechnik.com for more technical information & downloads.
Air Top 3500/5000
Vehicles with Carburetor Engines
In passenger cars, fuel may only be extracted with the spe-
cial Webasto fuel pickup (see Fig. 8) and as close to the
tank as possible. The connection can be made either in
the flow or the return pipe whereby it must be ensured that
the return pipe reaches almost to the bottom of the tank.
Failing this, the return pipe can be extended.
The fuel pickup is to be so mounted that any air or gas
bubbles are automatically discharged into the tank (see
Fig. 9).
to engine
from tank
to metering pump
Fig. 9: Webasto Fuel Pickup
Fuel should not be extracted in the vicinity of the engine
since here gas bubbles are likely to form in the lines owing
to the heat radiation of the engine, which may result in mal-
functions of the combustion operation.
8
Vehicles with Fuel Injection Engines
When installing the heater in vehicles with petrol injection
systems it must be determined whether the fuel pump is
mounted inside or outside the tank.
Where the fuel pump is located inside the tank, the fuel
can only be drawn from the return pipe and only by using
the Webasto fuel pickup (see Fig. 8) whereby it must be
ensured that the return pipe reaches almost to the bottom
of the tank (minimum distance to tank bottom, see Fig. 10).
Failing this, the Webasto tank extracting device (see Figs.
9, 10 and 11) can be used.
Where the fuel pump is mounted outside the tank, the fuel
may only be extracted between the tank and the fuel pump
and also only by using the Webasto fuel pickup (see Fig. 8).
Vehicles with Diesel Engines
Fuel must be drawn from the fuel tank or a separate tank
(see Figs. 9, 10 and 11). With this method of fuel being
supplied from a separate tank, no pressure-related in-
fluence is possible.
www.butlertechnik.com
hole pattern
minimum distance 25 mm
Fig. 10: Webasto Tank Extracting Device
* tank extracting device only to be used with
metal fuel tanks
plastic tank
sealing ring
Fig. 11: Fuel Extraction From the Plastic Tank
(Extraction Via Tank Drain Plug)