Cummins/Onan 7.5MDJE-18R Generator Set

⚠ Do not force needles against seats.

1. Open both needles 1 to 1-1/2 turns off seats.
2. Apply full load; turn main fuel screw in until speed drops, then out to normal.
3. Remove load; turn idle screw out until speed drops, then in to normal.

1. Loosen locknuts on governor linkage, remove link at one ball joint.
2. Position governor arm and fuel control arm fully forward.
3. Adjust linkage so both ball joints fit without moving arms.
4. Tighten locknuts.
5. Release fuel solenoid plunger.

Tools: feeler gauge, socket wrench

1. Turn flywheel to compression stroke for cylinder to adjust.
2. Turn flywheel clockwise additional 10 to 45 degrees.
3. Loosen locknut to increase clearance, tighten to reduce.
4. Use feeler gauge to set proper gap.
5. Adjust in firing order 1-2-4-3.

Tools: feeler gauge, wrench

1. Remove valve covers.
2. Crank engine until intake valve opens and closes.
3. Continue 1/4 turn until timing marks align.
4. Turn adjusting screw to obtain correct clearance.
5. Use flat feeler gauge between valve and valve rotator.

⚠ Avoid overcharging.

Tools: DC ammeter

1. Set slide tap on resistor R4 to about 2 amperes charging rate.
2. For frequent starts, increase charge rate slightly until battery stays charged.
3. Stop engine when readjusting to avoid shorts.

1. Remove flywheel and examine breaker points.
2. Adjust gap to .022 inch (0.56 mm) at full separation.
3. Loosen screw to shift point set, retighten securely.

Tools: continuity light, thickness gauge

1. Crank engine to fully open breaker points.
2. Loosen locking screws and turn cam to adjust.
3. Set point gap to .020 inch (0.51 mm).
4. Shift breaker point box to align timing mark.

Tools: depth micrometer

1. Install pump tappet in recess, position flywheel on port closing mark.
2. Measure distance from mounting pad to tappet center.
3. Subtract from 1.670-inch port closing dimension.
4. Select correct shims and install pump.

Tools: AC voltmeter

1. Set voltage adjust potentiometer halfway if present.
2. With unit running at no load, turn R26 clockwise to increase voltage.
3. Turn R26 counterclockwise to decrease voltage.

1. With generator at no load, turn R27 until voltage hunts.
2. Turn R27 clockwise slowly until voltage stabilizes.

Tools: Wheatstone bridge, ohmmeter

1. Use Wheatstone bridge.
2. Disconnect main rotor field leads at F1+ and F2-.
3. Disconnect diode leads CR1-CR6.
4. Measure between T1-T2, T2-T3, T1-T3; should be 0.5 to 0.6 ohms at 68°F.
5. Measure each CR lead to laminations; should be infinity.

Tools: ohmmeter

1. Disconnect F1+ and F2- from terminal block.
2. Measure resistance between field leads; should be 11 to 13.4 ohms at 68°F.
3. Measure from either field lead to laminations; should be infinity.