119
Model Code Page
22. Fuel system
1. 8. 1998
8050--8550 223
11
1. 4. 1997
C. Bleeding fuel system
Note! This fuel system removes automatically small amounts
of air bubbles from the filter and the pump when the engine
is running. However, bleed the system always, when the sys-
tem has been opened orfuel has been exhausted during driv-
ing or a new spare pump has been fitted (toavoid long starting
time).
Metal gauze filter
under cover
1. Pump by hand the fuel feed pump lever. If the pumping
seems to be ineffective, turn the engine a little so that the cam-
shaftcamisnotatthefeedpumplifter.
2. Loosen the bleeding screw (10a) on the filter. Pump with the
hand pump until no air bubbles flows out of the bleeding
screw hole. Tighten the bleeding screw.
3. Pump further with the hand pump and loosen the fuel inlet
connection (10b) on the pump, until the fuel coming out is free
from air bubbles. Tighten the connection.
4. Start the engine and assure, that no leaks exist.
Note! When the bleeding is done in this way, fuel flows
immediately into the internal transfer pump when the starter
motor is rotating and the distributor pump housing is filled
quickly with fuel. In the pump housing there is a stop solenoid,
which must not be switched on for longer periods when the
pump housing is empty of fuel.
D. Fuel feed pump
For the membrane type fuel feed pump no spare parts are
supplied. The feed pump must be changed for a new one, if
the feed pressure has dropped noticeably (rated feed pres-
sure is 0,2---0,5 bar at low idling speed and max 0,2 bar less
when engine is accelerating) or if the fuel feed pump has
been damaged.
Measuring fuel feed pressure
Measuring equipment, see page 220/3.
Note! If the feed pressure value is below the rated value,poss-
ible reason can be:
--- blocked fuel filter/fuel feed pump metal gauze filter
--- faulty fuel feed pump
--- blocked or leaked fuel pipes or pipe connections
Important! Under the fuel feed pump cover there is a wash-
able metal gauze filter. If much impurities have gathered on
this filter, fuel cannot flow t o the feed pump and further to the
injection pump and t his caus es malfunctions in the fuel sys-
tem. Always when malfunctions appear, the feed pump cover
should be removed and the metal gauze filter must be
checked and cleaned.
Note! From manufacturing week G42 incl. the fuel feed pump
gasket no. 8366 40335 has been removed and the sealing has
been done with sealing glue T61050 (Weicon Lock AN
305---10 or 75), which must also be used in connection with
possible leakages. Run the engine, until the cylinder block
temperature is at least +60˚C. Clean the sealing surfaces well
by using suit able solvent. Apply the sealing glue onto the
pump sealing face and fasten the pump. Let the sealing glue
dry about one hour before the engine is started (if a fuel feed
pump, which has been tightened with the sealing glue,should
be changed, the pump fastening flange must be warmed up
to about +200˚C before removing the pump).
New fuel feed pump
In the tractor production has been started to fit a new fuel feed
pump (420: H7663---. 620, 634: H7728---), which has an
o---ring seal and four fixing bolts. This pump can be fitted also
on earlier manufactured tractors, although they should have
the earlier, with two bolts attached pump (mounting kit no.
8366 62052). In the cylinder block there are four fixing holes
from the beginning of the year 98. The Spare Part Centre dis-
patches only the new pump.
On the next page there is an instruction on, how to fit the new
pump.
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