Specifications
| Fuel | Gasoline |
|---|---|
| Frequency | 50.0 Hz |
| Standby power | 7 kW |
| Prime power | 6 kW |
| Oil capacity | 6.15 L |
| Alternator | Cummins/Onan YD Revolving Field, 4-Pole Brushless (4-pole) |
| Voltage options | 120 V, 240 V |
| Phase | 1 |
| Battery voltage | 12 V |
| Battery quantity | 1 |
| Coolant capacity | 11.4 L |
Engine
| Oil capacity | 6.15 L |
|---|---|
| Coolant capacity | 11.4 L |
| Aspiration | Naturally Aspirated |
| Rated speed | 1800 rpm |
Maintenance & consumables
for the Cummins/Onan J Series| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | Polyurethane foam air cleaner element | — | 200 hr | find | |
| Fuel filter | Fuel filter with sediment bowl | — | 100 hr | find | |
| Oil filter | Spin-on oil filter | — | 500 hr | find | |
| Belt | Drive belts and fan belt, deflection 0.5 in at 15 lbs force | — | 500 hr | find | |
| Coolant | Rust inhibitor and water or 50/50 antifreeze mix | 11.4 L | — | 500 hr | |
| Coolant filter | — | find | |||
| Oil | API SF/CD, 20W-40 or 20W-50 at 60-100F | 6.15 L | — | 500 hr |
Common questions
What is the power rating of the Cummins/Onan RJ?
The Cummins/Onan RJ is rated 7 kW standby.
What engine does the Cummins/Onan RJ use?
The Cummins/Onan RJ is powered by the Cummins/Onan J Series engine.
What fuel does the Cummins/Onan RJ use?
The Cummins/Onan RJ runs on Gasoline.
What is the oil capacity of the Cummins/Onan RJ?
The Cummins/Onan J Series engine in the Cummins/Onan RJ has an oil capacity of 6.15 liters.
What alternator does the Cummins/Onan RJ use?
The Cummins/Onan RJ uses a Cummins/Onan YD Revolving Field, 4-Pole Brushless alternator. It has 4 poles.
Troubleshooting
20Symptoms & remedies
| Symptom | Cause | Remedy |
|---|---|---|
| Dizziness | If you experience any of these symptoms, get out into fresh air immediately, shutdown the unit and do not use until it has been inspected. | |
| External coolant leakage may occur at any joint in the engine water jacket, such as drain plugs, core hole plugs, or cylinder head joint. | Since expansion or contraction can aggravate leakage, the block should be inspected both hot and cold while engine is running. | |
| Internal leakage occurs when coolant passes into engine oil through a loose cylinder head joint or a cracked or porous casting. | The leakage is not visible but may cause extensive damage to engine. Coolant mixes with the oil to form sludge, which causes lubrication failure. Heavy sludge accumulations followed by sticking piston rings, valves, and tappets are symptoms of internal leakage. | |
| Thermostat does not start to open when suspended in water at 150°F or does not close within a short time after being removed from hot water. | Replace thermostat if it is broken, corroded, or sticks in open or closed position. If engine overheats or does not reach and maintain a minimum operating temperature, thermostat should be removed and tested as a possible cause. | |
| Draining cooling system to change anti-freeze solution or for out-of-service protection when only water is used, be sure to open all drains and hose connections where water could be trapped. | The following drain plugs must be opened or removed to allow complete flushing of the cooling system. Radiator: One petcock lower right front corner. Engine Block One drain plug left front near water pump. Water Pumps: One drain plug under cover or by loosening cover. | |
| Pressure cap malfunctions. | Inspect pressure cap periodically for freedom of operation, and gasket should be checked for proper sealing. Replace pressure cap if it malfunctions. | |
| HIGH WATER TEMP lamp lights. | Engine has overheated (engine temperature has risen above 215°F (101°C), or coolant level is low) | Allow engine to cool completely before proceeding with the following checks: a. Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary. b. Check for obstructions to cooling airflow and correct as necessary. c. Check for slipping fan belt and tighten if loose. d. Reset control and restart after locating and correcting problem. Contact an Onan representative if none of the above. |
| LOW OIL PRESSURE lamp lights. | Engine oil pressure has dropped to 14 psi (97 kPa) | Check oil level and replenish if low. Reset control and restart. Contact an Onan dealer or distributor if oil pressure is not in the range of 30 to 35 psi (207 to 241 kPa). |
| Cranking Limiter pops out and engine stops cranking. ENGINE FAILURE TO START lamp lights. | A. Check for empty fuel tank, fuel or leaks, or plugged fuel lines and correct as required. b. Check for dirty fuel filter and replace if necessary (see Maintenance section). c. Check for dirty or plugged air filter and replace if necessary (see Maintenance section). d. Check for loose connections in the ignition primary, ignition secondary or solenoid valve circuits and correct as required. e. Reset the control and restart after correcting the problem. Contact an Onan distributor for service if none of the above. | |
| Engine runs and then shuts down, OVERSPEED lamp lights. | Contact an Onan distributor for service. | |
| Fault lamp lights but no fault exists. | Reset control. If control will not reset, sensor may be at fault. | |
| Engine will not crank. | A. Fault lamp on. Correct fault and reset control. b. Poor battery cable connections. Clean the battery terminals and tighten all connections. c. Discharged or defective battery. Recharge or replace the battery. d. Contact an Onan distributor for assistance if none of the above. | |
| No AC output voltage. | Field breaker is tripped. Reset breaker. Contact an Onan distributor if voltage buildup causes breaker to trip. | |
| Engine does not crank. | Battery dead, loose connections, incorrect wiring, or faulty starter motor. | Check 12 VDC to ground at battery BT1 and at starter motor Bl. Check B+ present at TB11, K13, S1, and M11. Check battery cables for polarity and tightness at battery and starter motor. If battery is dead, check if centrifugal switch S1 is open to ground. Replace S4 or charge battery. Jumper battery cable connection to ground at starter. Check starter motor. With S11 at START, jumper K11 contacts to starter solenoid. Start relay K11 is defective; replace it. |
| Engine cranks but does not start. | Faulty switch or lead connections. | Check 12 VDC present between start terminal on S11 and ground (TB11-1) with S11 at START. Check 12 VDC present between M11-B+ and ground TB11-1 with S11 at START. Replace faulty switch S11 if necessary. Check lead from TB12-4 to fuel pump; check fuel pump and replace if necessary. |
| Engine starts but stops when start switch is released. | Faulty switch or lead connections. | Connect voltmeter from 12 VDC to ground at battery BT1 and at starter motor Bl. Check B+ present at TB11, K13, S1, and M11. Check battery cables for polarity and tightness at battery and starter motor. If battery is dead, check if centrifugal switch S1 is open to ground. Replace S4 or charge battery. Jumper battery cable connection to ground at starter. Check starter motor. With S11 at START, jumper K11 contacts to starter solenoid. Start relay K11 is defective; replace it. |
| No build up of AC output voltage. | Is Field Breaker CB21 on control panel ON? If not, step 2. Connect jumper wire across terminals of Field Breaker, CB21. Does AC output voltage build up? If yes, replace Field Breaker. If no, push to reset Field Breaker. Does AC output voltage build up? If yes but is high, low, unstable, or causes tripping of Field Breaker, refer to Tables B, C, or D. If no, step 4. Disconnect alternator stator leads 1 & 2 from TB21-1 and TB21-2 on VR22. Is reference voltage across 1 & 2 20 VAC or more? If not, refer to step 14. | |
| AC output voltage builds up, but is unstable. | Are there any loose or broken wires or connections on voltage regulator assembly VR22? If yes, step 3. Is W9 (exciter field) wiring harness from VR22 to End bell OK? If no, replace PC Board VR21. Do not replace the printed circuit board until the trouble not on the PC board has been located and corrected to avoid damage to new PC board. | |
| AC output voltage builds up, but is high or low. | Is set running at correct RPM? (See appropriate engine manual to set RPM) If no, step 3. Does adjustment of Voltage Adjusting knob for R22 on VR22 result in correct output voltage? If no, step 4. Does adjustment of potentiometer R26 on VR21 result in correct output voltage? If no, refer to step 5. Is correct voltage reference V4 to V1, V2, or V3 on VR21 being used? Refer to Figure 6. If no, replace voltage regulator PC board VR21. Do not replace the printed circuit board until the trouble not on the PC board has been located and corrected to avoid damage to new PC board. | |
| AC output voltage builds up, but Field Breaker trips. | Does AC output voltage build up to 140% or more of rated voltage before Field Breaker trips? If yes, are there any loose or broken wires or connections on VR22? If no, is diode CR15 on VR21 OK? If no, are T21 windings and connections OK? If no, are generator stator leads properly connected? Refer to Figure 6. Replace VR21 if necessary. Are diodes CR1, CR2, CR3, CR4, CR5, CR6 in rotating rectifier assemblies OK? Check all diodes - more than one may be defective. Is brushless exciter stator winding OK? Is generator rotor field winding OK? If no, is brushless exciter rotor windings OK? |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Parts
11| Part # | Description | Qty | System | |
|---|---|---|---|---|
| A742 | REGULATOR - SOLENOID PRIME | 1 | Solenoid primer | eBay |
| X9079912 | Gas Regulator (Garretson) | Regulator | buy | |
| 102206606 | Safety Messages | Service part / kit | buy | |
| 10AT73 | T A B L E O F | Service part / kit | buy | |
| 55432 | 73RD AVENUE NE * MINNEAPOLIS. MINNESOTA | 1400 | Service part / kit | buy |
| A076 | SOLENOID COIL | 1 | Service part / kit | buy |
| g00640926 | Never spray Ether starting aids into the air inlet. | 1 | Service part / kit | buy |
| i02143194 | Crushing Prevention and Cutting Prevention | Service part / kit | buy | |
| i02143195 | Obey all local regulations for the disposal of liquids. | 1 | Service part / kit | buy |
| i02203039 | Attach a 'Do Not Operate' warning tag or a similar warning tag to the start switch or to the controls before you service the equipment or before you repair the equipment. | 1 | Service part / kit | buy |
| i02206606 | Safety Messages | 1 | Service part / kit | buy |
Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.
Fuel consumption
| Rating | Load | L/h | gal/h |
|---|---|---|---|
| Prime | |||
| Standby |
Available documents
Operator's manual — 974-0120 Onan RJC (spec A-AC) Genset Operator's manual (10-1988) (Cummins/Onan)Operator's manual — 974-0300 Onan RJC Operator's and Parts Manual (10-1973)Parts manual — 932-0109B Onan Engine & Genset Short Block Index (10-1998) (Cummins/Onan)Parts manual — DK-Kohler (Cummins/Onan)Parts manual — NET-Onan (Cummins/Onan)Service manual — 900-0184 Onan YD Generators & Controls Major Service manual (10-1975) (Cummins/Onan)Service manual — 967-0757 Onan RJC MJB MJC Gas Engine Service Manual 11-1986 (Cummins/Onan)