8 Servicin
BBW 46 / DBW 46
806
Air or gas bubbles may build up in the vehicle fuel line in
case the carburettor or the fuel pump is leaking or if
ambient temperatures exceed the fuel evaporation
temperature.
The fuel tap should not be located near the engine, as gas
bubbles may build up due to the heat radiated by the
engine resulting in malfunctions of combustion operation.
When installing the heater in vehicles with fuel injection
system, the fuel pump location, internal or external of the
fuel tank, must be investigated.
With a fuel pump located inside the fuel tank, fuel may be
tapped only from the return line, ensuring that the return
line is routed almost all the way down to the fuel tank floor.
Otherwise the return line may be lengthened or fuel taps
(Fig. 805 and 806) may be used.
With a fuel pump located outside of the fuel tank the fuel
tap may be located between tank and fuel pump.
Fig. 805 Webasto Fuel Tank Tap
Fig. 806 Fuel Tapping from Plastic Tank
(tapping via fuel drain plug)
8.6.2.1 Fuel Lines
Fuel lines may only be steel, copper, or plastic lines made
of unhardened, light and temperature stabilised PA 11 or
PA 12 ( e.g. Mecanyl RWTL) according to DIN 73378. As
in most cases a permanently rising fuel line routing cannot
be ensured, the inner diameter must not exceed a certain
value. Starting from an inside diameter of 4 mm, air or gas
bubbles accumulate resulting in malfunctions should the
lines be descending or having sags. The diameters
specified in Fig. 803 ensure no disturbing formation of
bubbles.
A descending line routing from the dosing pump to the
heater should be avoided.
Loose fuel lines must be secured in order to avoid
sagging. The installation must ensure protection against
stone impacts and
undue temperatures
(exhaust line).
The fuel line joints are to be secured against slipping with
hose clamps.
C
onnection of 2 Pipes with Hose
The proper connection of fuel lines with hose is shown in
Fig. 807.
> 25 mm
25
Hole pattern
Use fuel tank tap only
on metal fuel tanks
Plastic Tank
asket
(41 Seiten)
(18 Seiten)
(72 Seiten)
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