Cummins/Onan DJA Engine Engine
The Cummins/Onan DJA is a 0.49 L 1-cylinder air-cooled engine rated at 2400 rpm, producing up to 5.4 kW. It powers generator sets from Cummins/Onan, including the 2.5DJA-51R, 2.5DJA-52R, 3.0DJA and 4.0DJA-FJ.
Also known as: Onan DJA
Engine specifications
| Displacement | 0.49 L |
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| Cylinders | 1 |
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| Aspiration | Air-cooled |
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| Rated speed | 2400 rpm |
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| Gross power | 5 kW |
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Generator sets powered by this engine
7Common problems
15- Engine losing speed momentarily or low engine power
Cause: Dirty cooling surfaces, operating without the engine air housing, poor air circulation, improper lubrication, wrong injection timing and engine overload. - Temperature Sending Unit fault 24
Fix: -Check -Connections in wiring harness -Switch continunity - Temperature Sending Unit 24
- Starter Solenoid Circuit - controller senses a short circuit 21
Fix: - Check Connections at starter motor - Shorts and/or grounds at solenoid - Speed Sense Fault−controller does not sense quadrature frequency and voltage 45
Fix: -Check -F2 Fuse -Starter circuits -K2 relay and connections -Rotor/stator windings for opens/shorts/ grounds - Speed Sense Fault 45
- Quadrature Sense Fault 28
- Low Oil Pressure Cutoff Switch fault 23
Fix: -Check -Perform fuel flow test -Governor linkage for binding -High idle adjustment -Injectors -Injection pump timing -Compression - Low Oil Pressure Cutoff Switch 23
- Invalid Genset Configuration 37
- High Battery Voltage 29
- Governor Actuator Overload - duration of operation at or near full-duty cycle is beyond the design limit 22
Fix: - Check Load - Air intake restriction - Exhaust restriction - Air leak in fuel system - Field Overload 38
- External Coolant Loss 010
Fix: -Visually check for: -Coolant level is OK -Cracked or leaking hoses -Loose clamps -Leaks or defects in radiator -Coolant in oil - Excessive White Exhaust Smoke at Start-up (Warm Engine) 47
Fix: -Check: -Glow plug operation -Low engine operating temperature -Valve settings -Air leaks in fuel system
Compiled from service & troubleshooting documentation across every generator set that uses the Cummins/Onan DJA.
Maintenance schedule
| Item | Spec | Capacity | Part # | Interval | |
|---|
| Air filter | | | — | | find |
| Fuel filter | Change primary fuel filter every 300 hours and secondary fuel filter every 1200 hours. | | — | 300 hr | find |
| Oil filter | Change crankcase oil every 50 operating hours. Replace oil filter as per schedule. | | — | 50 hr | find |
| Belt | Inspect and replace as necessary. Adjust valve clearance after first 50 hours on a new or overhauled engine. | | — | 50 hr | find |
| Coolant | Drain water periodically from both filters and sediment bowl. Replace primary filter every 600 hours, secondary filter every 3000 hours. | | — | 600 hr | |
| Oil | | | — | | |
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
Repair guides
4Step-by-step procedures compiled from the Cummins/Onan service manual for this engine.
Common questions
What is the displacement of the Cummins/Onan DJA?
The Cummins/Onan DJA has a displacement of 0.49 liters with 1 cylinders.
Which generators use the Cummins/Onan DJA engine?
The Cummins/Onan DJA powers 7 generator set(s), including Cummins/Onan 2.5DJA-51R, Cummins/Onan 2.5DJA-52R, Cummins/Onan 3.0DJA, Cummins/Onan 4.0DJA-FJ, Cummins/Onan DJ.
What is a common problem with the Cummins/Onan DJA engine?
A commonly reported issue on generators using the Cummins/Onan DJA is: Engine losing speed momentarily or low engine power. Cause: Dirty cooling surfaces, operating without the engine air housing, poor air circulation, improper lubrication, wrong injection timing and engine overload..