Cummins/Onan Onan P4500i Generator Set

⚠ Must be done when the engine is cold.

Tools: Feeler gauge

1. Remove rocker arm cover and gasket; replace gasket if damaged.
2. Remove spark plug to ease rotation.
3. Rotate engine to TDC of compression stroke.
4. Confirm both rocker arms loose at TDC; rotate 360 degrees if not.
5. Insert feeler gauge between rocker arm and push rod; check clearance.
6. If needed, hold adjusting nut and loosen jam nut.
7. Turn adjusting nut to obtain correct valve lash.
8. Tighten jam nut to 106 in-lb (12 N.m) while holding adjusting nut.
9. Recheck valve lash after tightening.
10. Repeat for both intake and exhaust valves.
11. Install rocker arm cover, gasket, and spark plug.

⚠ Checking and adjusting valve clearance must be done when the engine is cold

Tools: Feeler gauge, Wrench

1. Turn the generator off and allow the engine to cool for 30 minutes; work on a cold engine.
2. Place the generator on a level surface in a well-ventilated area.
3. Remove the engine service cover.
4. Remove the rocker arm cover and carefully remove the gasket.
5. Remove the spark plug so the engine can be rotated more easily.
6. Pull the recoil handle to rotate the engine to top dead center (TDC).
7. Verify both rocker arms are loose at TDC on the compression stroke; if not, rotate the engine 360 degrees.
8. Insert a feeler gauge between the rocker arm and the valve stem to measure valve clearance.
9. If adjustment is needed, hold the rocker arm pivot and loosen the pivot adjusting nut.
10. Turn the rocker arm pivot to obtain the specified clearance; hold the pivot and re-tighten the nut to the specified torque.
11. Recheck valve clearance and perform the procedure on the other valve if needed.
12. Install the gasket, rocker arm cover, and spark plug.

1. Depress the tab on the battery access cover and pull it away from the generator.
2. Verify that the rubber battery strap is firmly securing the battery in place.
3. Remove the cable tie securing the quick-connect plugs then push firmly to connect them.
4. Reinstall the cover.

⚠ This high-altitude kit is to be used at elevations above 2000 feet

⚠ DO NOT operate the generator at altitudes below 2,000 ft (762 m) with the high-altitude kit installed

Tools: Flat head screwdriver, Wrench

1. Remove battery access panel and disconnect the battery.
2. Remove the maintenance panel on the side by removing the 5 bolts that secure it.
3. Remove the control panel by removing the 4 face screws and the two screws on each side; let it hang loose.
4. Drain all the fuel from the carburetor float bowl into a suitable container.
5. Remove the two bolts that secure the air filter box to the carburetor; remove the lid and foam element.
6. Remove the clamp on the vapor tube; remove the vapor tube and crankcase breather.
7. Remove the two nuts that hold the box base to the carburetor and slide it off.
8. Remove the gasket from the carburetor front face; remove the two electrical connections from the stepper motor.
9. Slide the carburetor off the studs and turn it sideways to remove the fuel line.
10. Remove the bolt at the bottom of the float bowl and remove the float bowl.
11. Using a flat head screwdriver, remove the main jet; the jet and emulsion tube will fall out.
12. Install the emulsion tube back into the carburetor with the ridge on top going in first.
13. Select the appropriate jet for your altitude and install it with a flathead screwdriver.
14. Reinstall the float bowl gasket and the float bowl.
15. Reinstall the carburetor, gasket, air filter box, control panel, and side panel; start and verify operation.

⚠ Always connect positive cable first; disconnect negative cable first.

1. Unclip battery access panel on back of unit.
2. Pull down battery strap clip and unhook from mounting base.
3. Lift battery, withdraw bottom-first, stand vertically.
4. Clip battery quick connect to main lead inside inverter.
5. Verify positive cable securely tightened to positive post.
6. Insert battery top-first through access port, stand on mounting base.
7. Check battery positioned correctly, cables not kinked.
8. Pass strap under negative cable and over battery top, hook to base.
9. Replace battery access cover.

⚠ This generator has been shipped without oil

Tools: Funnel

1. Turn the generator off and allow the engine to cool for at least five minutes.
2. Place the generator on a level surface in a well-ventilated area.
3. Depress the tab on the oil access cover and pull it away from the generator.
4. Clean the area around the oil dipstick.
5. Slowly unscrew and remove the oil dipstick.
6. Using the funnel, slowly pour the supplied engine oil into the oil fill hole; do not overfill.
7. Replace and tighten the oil dipstick.
8. Install the engine service cover and secure with screws.

1. Plug the charger into the battery charging port on the control panel.
2. Plug the wall receptacle end of the battery charger into a 120 Volt AC wall outlet.
3. A red light on the charger indicates charging in progress; a green light indicates charging complete.
4. Charge in a dry location.

⚠ Always connect the cables in the specified sequence to avoid possible shock

1. Depress the tab on the battery access cover and pull it away from the generator.
2. Disconnect the quick-connect plug and battery strap, then remove the battery from the generator.
3. Disconnect the quick-disconnect cable leads from the battery.
4. On the replacement battery, connect the white (-) quick-connect cable to the negative terminal; slide the rubber boot over the connection.
5. Connect the red (+) quick-connect cable to the positive terminal; slide the rubber boot over the connection.
6. Lift the battery strap and install the battery; thread the strap under the cables and secure on the mounting base.
7. Connect the quick-connect plug and install the battery access cover.

⚠ Never dispose of used oil in a sewer, on the ground, or into waterways.

Tools: 10mm wrench, Oil pan/container, Rag

1. Stop the engine.
2. Let engine cool for several minutes.
3. Remove the oil service panel.
4. Place oil pan under rubber plug below the oil service panel.
5. Remove rubber plug to drain oil from the bottom.
6. Remove oil drain bolt with a 10mm wrench to allow draining.
7. Allow oil to fully drain; dispose of properly.
8. Refill crankcase with oil and tighten the oil plug.
9. Wipe excess oil, replace rubber cap and drain bolt, replace access panel.

⚠ Change the oil while the engine is warm but not hot

Tools: 10mm wrench, Oil pan, Funnel

1. Turn the generator off and allow the engine to cool for 30 minutes.
2. Depress the tab on the oil access cover and pull it away from the generator.
3. Slowly unscrew and remove the oil dipstick.
4. Remove the rubber plug under the oil drain bolt and place an oil pan under the drain hole.
5. Using a 10mm wrench, remove the oil drain bolt and allow the oil to drain.
6. Reinstall the oil drain bolt and rubber plug.
7. Refill the oil as described in the Operations section.
8. Replace the oil dipstick and hand-tighten; reinstall the cover.

⚠ Allow crankcase pressure to equalize before removing dipstick.

Tools: Oil fill bottle

1. Operate/maintain inverter on a flat surface.
2. Stop engine if running.
3. Let engine cool for several minutes.
4. Remove oil service panel to access oil plug/dipstick.
5. Clean around oil plug/dipstick with a damp rag.
6. Remove the oil plug/dipstick.
7. Check oil level; oil should be visible on the dipstick's cross threads.
8. If low, add oil using the supplied oil fill bottle; do not overfill.

⚠ Never use gasoline or flammable solvents to clean the air filter.

Tools: Household detergent soap

1. Turn off inverter and let cool.
2. Remove the engine service panel.
3. Turn 2 knobs on air cleaner to unlock cover; tip cover down.
4. Remove the foam element from the housing.
5. Wash foam element in detergent soap and warm water, squeezing gently.
6. Rinse element in clean water with a slow squeezing action.
7. Dry element with a slow, firm squeezing action.
8. Return element to housing and install cover, locking knobs.
9. Install the engine service panel.