144
12
Inj
ection
timin
g
shims
CHAPTER
SEVEN
5. Loosen the fitting nut (Figure 12) on the injcctor(s)
just enough to expel fuel.
6. Move the engine speed control to the full throttle posi-
tion.
7. Move the decompression lever to the ON position.
NOTE
Do not operate the starter
for
more than 30
seconds; otherwise tile starter may be dam -
aged due
to
overheating.
8. Operate the starter until air-free fuel flows from the in-
jcctorfs).
9. Tighten the injector fuel line fitting nutfs) to 20
Nom
(15 ft.-lb.).
10. Operate the starter and listen for the distinctive noise
that indicates the injector is operating.
FUEL INJECTION TIM ING
Similar to ignition timing on a gasoline engine, the fuel
must be injected at the proper time to obtain optimum
combustion,
Injection timing is determined by the relationship be-
tween the injection pump plunger and the injection cam-
shaft inthe engine. The rotatingcam acts against the roller
on the pump plunger in the fuel injection pump (Figure
13) to force up the plunger and pump fuel to the injector
nozzle. Moving the fuel injection pump up or down on its
mounting surface changes the point on the cam that the
plunger begins vertical movement, thereby changing
when injection occurs.
Shims between the injection pump and its mounting
surface on the engine are used to adjust fuel injection tim-
ing (Figure 13). Increasing shim thickness retards injec-
tion timing, while decreasing shim thickness advances
injection timing.
'-\\!;Z;if:='--
- - Plunge r r
oll
er
'1-
- - Fuel
inje
cti
on
cam
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