Cummins/Onan 5.0BF - 34 3E Generator Set

⚠ Damage will result if needle is forced against its seat.

1. Run engine to normal operating temperature.
2. Make idle adjustment under no load.
3. Open main jet until engine runs smooth under acceleration with no load.
4. Open about 1/4 turn further if needed for sudden load.
5. Set throttle stop screw to 1/32 in clearance.
6. If hunting, open main needle a little more; do not exceed 1/2 turn beyond maximum power.

1. Invert float assembly and casting.
2. With float resting lightly against needle and seat, clearance between bowl cover gasket and free end of float should be 1/8 in.
3. If reset needed, bend float tangs near pin to obtain 1/8 in clearance.

Tools: tachometer

1. Adjust carburetor main jet for best full load mixture.
2. Adjust carburetor idle needle with no load.
3. Adjust length of governor linkage.
4. Check governor linkage and throttle shaft for binding or looseness.
5. Adjust governor spring tension for nominal no-load speed.
6. Check rpm drop from no-load to full-load and adjust sensitivity.
7. Recheck speed adjustment.
8. Set carburetor throttle stop screw.

Tools: 7/16 in open end wrench, 9/16 in open end wrench, feeler gauge

1. Remove parts to gain access to valve tappets.
2. Remove spark plugs to ease turning crankshaft.
3. Rotate flywheel until left intake valve opens and closes; align TC mark. Both valves closed.
4. Intake: .007 in gauge should pass freely; .009 in should not.
5. Exhaust: .012 in gauge should pass freely; .014 in should not.
6. Use 7/16 in open end wrench to turn adjusting screw; hold tappet with 9/16 in wrench.
7. For right cylinder, turn engine one revolution and align TC mark; repeat.
8. Replace all parts and tighten screws; torque manifold bolts.

Tools: screwdriver, flat thickness gauge

1. Remove control box cover screws and cover.
2. Disconnect wire from control box to ignition coil; remove front panel.
3. Remove breaker box cover.
4. Remove spark plugs to rotate crankshaft by hand.
5. Remove points mounting nut and disconnect leads.
6. Replace condenser and points.
7. Rotate crankshaft clockwise to align 25° BTC mark; turn 1/4 turn more.
8. Set point gap to .025 in; tighten nut and recheck.

⚠ Do not use a substitute brush.

1. Remove generator fan guard and fan.
2. Detach brush guide by removing end bell screws.
3. Tag leads 5 and 6; unscrew brush retaining screws and pull brushes.
4. Inspect brush faces for smooth coppery cast; no deep grooves.
5. Replace brushes if worn to less than 5/16 in length.
6. Work brushes up and down in guide to ensure no binding.

1. Run engine until thoroughly warm.
2. Turn off fuel supply and run until engine stops.
3. Drain oil while warm; refill and attach warning tag.
4. Remove spark plugs; pour 1 ounce rust inhibitor or SAE50 oil into each cylinder; crank and reinstall plugs.
5. Service air cleaner.
6. Clean governor linkage and wrap with clean cloth.
7. Plug exhaust outlets; wipe unit and coat rustable parts.
8. Disconnect battery; provide suitable cover.

⚠ Do not touch welder terminals while operating.

1. Adjust choke according to temperature conditions.
2. Move ignition switch to ON.
3. Push START switch firmly. If unit does not start within a few seconds, release and wait.
4. If unit does not start after two attempts, open choke and repeat starting sequence.

⚠ Use care when reassembling; all parts must be perfectly aligned.

1. Remove vacuum line and fuel line.
2. Remove two fuel pump attaching screws.
3. Grasp pump and carefully pull apart.
4. Diaphragm, plunger, return spring, pump body and gaskets will be loose.
5. Internal parts are available in a repair kit.