Cummins/Onan W3M-19 Generator Set

⚠ Do not turn either needle tightly into its seat or seat may be damaged

Tools: Screwdriver

1. Run engine to normal operating temperature.
2. With 1500 to 3000 watts load, turn main jet needle out 3 turns.
3. Turn main jet needle in until engine loses power and speed.
4. Turn needle out slowly until engine regains maximum power and speed.
5. With no load, turn idle jet needle in until engine loses considerable speed.
6. Turn idle jet needle out until engine runs smoothest.
7. Approximate start: turn both needles in, then out about 2-1/2 turns.

⚠ Do not use a fan belt until it breaks

⚠ Too tight a belt causes unnecessary wear on fan bearing

Tools: Wrenches

1. Loosen the cap screws which hold the fan bracket.
2. Raise or lower the bracket to adjust belt tension.
3. Correct tension allows one side of belt pushed inward about 1/4 in. midway between pulleys.
4. Tighten the cap screws securely.

⚠ If no-load and full-load voltages cannot be kept within limits, engine or generator brush adjustment needs attention

Tools: Screwdriver, wrenches, A.C. voltmeter (control panel)

1. Run power unit at normal operating temperature with no load.
2. Loosen main adjusting stud locknut.
3. Turn adjusting nut on stud to obtain correct generated voltage.
4. Turn nut clockwise to raise voltage, counterclockwise to lower.
5. Check voltage at full 3 kw resistance load; should not drop below 115 volts.
6. Adjust sensitivity adjusting stud to eliminate hunting.
7. Tighten the locknut.

⚠ Do not crank engine while gear housing is off the magneto

Tools: Feeler gage .015 in., Screwdriver

1. Remove distributor cap and inspect breaker contacts.
2. Clean pitted or eroded contacts, file pyramids square.
3. Loosen screw holding stationary contact bracket.
4. Move bracket by turning eccentric headed screw in open slot.
5. Adjust gap to .015 in.
6. Tighten holding screw and recheck gap.
7. Work CG grease into cam oil pad and reinstall.

⚠ Do not crank engine while gear housing is off the magneto

Tools: Hand crank, Screwdriver, wrenches

1. Remove No. 1 spark plug (nearer radiator).
2. Hold thumb over plug hole and crank slowly until compression felt.
3. Continue cranking until flywheel timing mark aligns with T.C. mark on crankcase.
4. Turn magneto gear in normal direction until impulse coupling just trips.
5. Distributor arm must point toward No. 1 tower.
6. Install magneto gear without turning distributor from position.
7. Crank engine slowly and note if coupling trips at timing marks.
8. If not, loosen magneto flange cap screws and turn frame slightly.

⚠ Reassemble using new gasket if available

⚠ Magneto must be retimed after installation

Tools: Feeler gages .006, .008, .010 in., Torque indicating wrench

1. Remove magneto and valve tappet inspection plate.
2. Tighten all cylinder head nuts to 50 foot-pounds if torque wrench available.
3. Crank engine until No. 1 valve closes and top center marks coincide.
4. Loosen cap screw in No. 2 exhaust lifter enough to push lever inward.
5. Insert .008 in. feeler gage between cam surface and lifter.
6. Pull lever outward without pinching feeler and tighten cap screw.
7. Recheck: .008 in. passes, .010 in. does not pass.
8. Adjust No. 1 intake lifter with .006 in. and .008 in. feelers.

Tools: Air hose

1. Remove thumb nut and lift cleaner from power unit.
2. Lift cover and element assembly from the cup.
3. Clean old oil and sediment from the cup.
4. Clean element by sloshing up and down in cleaning fluid or gasoline.
5. Allow element to dry or dry with air hose.
6. Fill cup to level mark with clean oil same as crankcase oil.
7. Reassemble and install cleaner, tightening thumb nut securely.

⚠ Plug exhaust outlet with a wood plug to prevent entrance of moisture or small animals

Tools: Hand crank

1. Drain fuel from tank and filter bowl, then run engine until it stops.
2. Drain all oil from oil base while engine is warm, replace drain plug.
3. Drain cooling system, leave caps on fuel tank, radiator and oil filler.
4. Remove spark plugs, pour two tablespoonfuls OE-30 oil in each cylinder, crank several revolutions, replace plugs with gaskets.
5. Clean generator brushes, holders, commutator and slip rings with clean cloth; do not coat with grease.
6. Disassemble and clean air cleaner, dip element in OE-30 oil, reassemble without oil in cup.
7. Wipe exposed parts and coat those liable to rust with a film of grease.
8. Oil throttle control link joints with OE-50 oil, plug exhaust outlet, install side panels and canvas cover.

1. Remove all protective grease coatings and wipe unit clean.
2. Inspect carefully for damage and correct it.
3. Remove the plug from the exhaust outlet.
4. Remove, clean and adjust spark plugs; crank engine several revolutions to distribute oil.
5. Clean magneto distributor cap and breaker contacts; install new spark plug cables if needed.
6. Examine fan belt, adjust or install new one as needed.
7. Examine radiator hose, install new hose if needed.
8. Check for leaks of gasoline, water and oil after filling; correct all leaks before starting.

Tools: Spark plug wrench

1. Remove the spark plugs.
2. Clean and inspect for cracked or badly eroded porcelain or electrodes.
3. Discard any plug not in good condition and replace with Champion 6M.
4. Adjust gap to .030 in.
5. Make sure gaskets are in place when installing.
6. Tighten securely.

⚠ Do not spin or push down on the crank

⚠ Do not overchoke

Tools: Hand starting crank

1. See that circuit breaker is in OFF position.
2. Pull out choke button as required by temperature; do not overchoke.
3. Remove starting crank and insert through hole below radiator.
4. Be sure crank engages positively with crankshaft ratchet.
5. Crank with a strong, quick, upward pull.
6. When engine starts, push choke button part way in.
7. Gradually push choke button entirely in as engine warms up.

⚠ Do not run power unit with canvas cover on

1. Disconnect load by throwing circuit breaker handle to OFF position.
2. Press the STOP button firmly until engine has entirely stopped.
3. Keep canvas cover installed when not to be operated within a few hours.