Technical data

BBW 46 / DBW 46 8 Servicin
g
805
8.6.2 Connection to Vehicle Fuel System
In vehicles with carburettor or fuel injection including a
return line the heater fuel system integration must be in
the return line.
Carburettor engines without return line must have the
heater integrated in the fuel system's fuel supply line
between fuel tank and vehicle fuel pump.
A fuel supply line can normally be identified by its fuel
filter.
The following table lists the pressures permitted at the fuel
tapping location.
NOTE
If a degassing vessel is included in the vehicle fuel system
installation, the fuel tap must be located upstream of the
degassing vessel.
Fuel tappings from the supply or return line may only use
the special Webasto fuel tap (Fig. 804).
The fuel tap is to be mounted so that air or gas bubbles
may escape towards the fuel tank.
Fig. 803 Fuel Supply
Fig. 804 Webasto Fuel Tap
Permitted fuel feed height
(H) m
at max. permissible over-
pressure (bar) in fuel tank
0.00 1.5
1.25 1.4
2.50 1.3
3.75 1.2
5.00 1.1
6.25 1.0
7.50 0.9
8.75 0.8
10.00 0.7
Permitted suction
height S (m)
at max. permissible
negative pressure (bar) in
fuel tank
0.00 (F; D) -0.15 (F; D)
0.50 (F; D) -0.11 (F; D)
1.00 (D) -0.07 (D)
F = Fuel D = Diesel
to engine
from tank
to dosing pump