Bleeding (Or Priming); Checkup Of Nozzles - Mitsubishi 4DQ50 Service Manual

4-2 Bleeding (or priming)
If air should get in fuel system, injection will go wrong, keeping the engine from
steady running or making it difficult to start. So, whenever any servicing done with this
system, bleed (or prime) it in the following procedure.
1) Loosen bleeding plug on fuel filter and move hand pump on fuel feed pump up
and down.
As fuel filter is fed full with fuel, air bubbles will run out with fuel through
bleeding plug. When the outflow of fuel does not contain air bubbles any
longer, screw bleeding plug tight.
2) Loosen bleeding plug on the top of injection pump, and move hand pump
like-wise up and down to eliminate air out of fuel pump in it.
3) With nozzle-side cap nuts
~n
injection pipes loosened and stop lever in
"full-open" position, run run the engine scores of revolutions by -starting
motor, and all four injection pipes will be bled of air at a time.
The bleeding must be done, too, when the engine has been left idle for a long
time, fuel pipes replaced, or nozzled checked.
Fig.3-16 Joint on fuel inlet in fuel feed pump Fig. 3-17 Bleeding fuel injection pump
4-3 Checkup
of
nozzles
When something unusual notices with exhaust gas or firing, check nozzles and
service accordingly.
Regular checking and servicing of them at intervals of 500Hr of run will keep them
always in perfect conditions. For new engine, check them when it has been run for
250Hr. Their checkup and serviCing should preferably be entrusted to your dealer or a
xervice shop.
1) Nozzles are checked by means of a nozzle tester. Set nozzle on the tester and
slowly pressing its hand lever, see how it will eject fuel. It must !flake
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