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78. To remove and test fuel injector
(a) Disconnect the fuel feed and leak-off pipes from the injector.
(b) Remove the injector flange nuts and carefully lever out the injector,
and on an AC1W engine, the nozzle shield washer
(c) Reconnect the injector to the pump-to-injector pipe in such a way that
the nozzle points away from the engine
(d) With the speed control lever, if fitted, in the full speed position, and with
the stop/run lever in the 'RUN' position turn the engine over slowly The
fuel should squirt out suddenly in a fine mist spray which should stop
as suddenly If the nozzle fails to spray, or gives a solid squirt of fuel. or
dribbles after the spray has stopped, fit a new nozzle
(e) When testing, BE CAREFUL to see that the spray is not directed at any
exposed part of the body The force behind the spray will cause it to
penetrate the skin
79. Fuel injector maintenance (Fig. 18)
(a) An injector servicing kit consisting of brass wire brush, nozzle scraper
and spray hole cleaner is obtainable from Fetters Ltd or their agents la)
Thoroughly clean the exterior of the injector.
(b) Remove the nozzle holder cap nut (A)
(c) Remove the spring adjusting screw (B) and remove the spring pad (C).
the spring (D) and the spring pressure rod (E)
(d) Remove the nozzle nut(P)and the nozzle assembly (G) Each needle of
a nozzle assembly is mated to one nozzle body and must never be
used in another.
(e) To ensure a thorough cleaning of all parts they should be left in a bath
of clean fuel. After this treatment, any remaining carbon can be
scraped off with a soft brass wire brush or piece of clean wood or
brass.
(f) The nozzle holder and nozzle joint faces must be clean with a mirror-
like appearance The nozzle and nozzle nut clamping shoulders must
be clean
(g) The nozzle body fuel holes (H) should be cleaned by pushing a wire or
twist drill (J)down into the fuel chamber (K) being careful not to scratch
the joint face.
(h) Insert a nozzle scraper (L) down into the fuel chamber, press sideways
and rotate to remove carbon, etc.
(i) Soft carbon can be removed from the spray hole with a spray hole
cleaner (M)
(j) Wash the nozzle body and needle in clean fuel and assemble wet.
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