Checking and Adjusting the Fuel Injection Advance Angle of a Single-Cylinder Diesel Engine

(I) Inspection

1. Disconnect the end of the high-pressure fuel line connected to the fuel injector and loosen the nut at the other end; rotate the fuel line so the injector-side opening faces upward, then retighten the nut at the other end.

2. Move the speed control lever to the maximum fuel delivery position, engage the decompression mechanism, and crank the engine to fill the high-pressure fuel line with diesel. Gently blow away any bulging fuel at the line opening or lightly tap the line to cause the fuel level at the opening to recede slightly; this makes observation easier.

3. Slowly rotate the flywheel; stop immediately the moment the fuel level at the line opening begins to move.

4. Observe whether the reference mark on the water tank aligns with the space between the two fuel injection timing marks on the flywheel.

Determining "Early" or "Late" Injection:

If the water tank mark aligns with the space between the two flywheel fuel injection marks (relative to the flywheel's direction of rotation), the fuel injection timing is correct. If the water tank mark appears before the two flywheel marks, the injection is "early." If the water tank mark appears after the two flywheel marks, the injection is "late."

(II) Adjustment

Adjustment is primarily achieved by adding or removing shims between the fuel injection pump and the timing gear housing cover. Removing shims moves the fuel injection pump slightly further away from the camshaft's fuel injection cam, thereby delaying the fuel injection timing; conversely, adding shims advances the timing.

Inconsistencies in measurement readings may occur during the inspection of the fuel injection advance angle; the primary reasons for this are:

① Severe wear on the plunger and delivery valve; or inconsistent flywheel rotation speeds during inspection.

② Uneven wear on the fuel injection pump roller and roller pin, resulting in an excessively loose fit between the two components. When checking the injection advance angle, if a severely worn section of the cam contacts the fuel pump, fuel delivery will be delayed; once the worn section passes, fuel delivery will occur too early.

(III) Determining the Top Dead Center (TDC) Mark on the Flywheel

Due to prolonged use, wear, or unclear factory markings on the housing and flywheel, adjusting valve clearance and checking or adjusting the fuel injection advance angle can be difficult.

1. Remove the fuel injector and insert a thin wire through the injector bore in the cylinder head and the main injection hole of the combustion chamber insert, extending it into the cylinder.

2. Slowly rotate the flywheel until the piston pushes the wire to its highest point.

3. Make a mark on the flywheel aligned with the reference mark on the housing; this serves as the flywheel's TDC mark. If there is no reference mark on the housing, you can mark both the housing and the flywheel simultaneously; the mark on the flywheel will then serve as the TDC mark.