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GM diesel engine injection pump timing

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Post by admin » Site Admin » Wed Mar 25, 2015 3:59 am
Joined: Fri Aug 24, 2012 5:56 pm
Posts: 1610
To check fuel pump timing rotate engine crankshaft in normal direction of rotation until flywheel 'P' mark is aligned with the clutch housing or converter housing (automatic transmission) aperture pointer with valves on No. 4 cylinder beginning to overlap.

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The timing mark on the camshaft sprocket should be approximately 12° before vertical.

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Remove centre screw plug from the fuel pump head.

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Install delivery checking adaptor with same thread as centre screw plug and lightly tighten.

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Assemble a dial gauge onto adaptor with some pre-­load on gauge spring.

On right drive vehicles it may be necessary to remove the heater to permit gauge and long adaptor installation.

If a gauge with a small diameter dial is available then the heater need only to be moved to one side after removing air intake securing screws.

Small gauge and short adaptor usually can be used without disturbing the heater.

Rotate crankshaft slightly in opposite direction of normal rotation until indicator pointer stops moving (the pump plunger now is at its lowest position). Adjuster indicator dial to zero.

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Rotate crankshaft in normal direction of rotation until flywheel 'OT' mark aligns with pointer in the clutch/converter housing aperture.

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If 'OT' mark is passed then turn crankshaft back beyond 'OT' mark and re­-approach in normal direction of rotation.

Fuel injection pump timing is correct if the gauge indicates as follows ­-

1.07 mm (0.042 in.) on 2.0 litre engine.
1.17 mm (0.046 in.) on 2.1 litre engine.
0.93 mm (0.037 in.) on 2.3 litre engine.

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If indicator reading is incorrect then slacken the two nuts securing pump to timing case and rotate pump until the indicator needle reading is correct.

Usually the injector pipes clamps and union nuts each end need to be slackened in order to rotate the pump without straining any pipes (which then could fracture in service).

Recheck timing by rotating the crankshaft in the opposite direction to normal rotation when the dial pointer should cease moving at the zero position.

Rotate crankshaft in normal direction of rotation until the dial pointer registers correct reading.

Flywheel 'OT' mark should be in alignment with clutch/converter housing aperture pointer.

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