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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 12592
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have an Onan 5500 model 5.5HGJAB-901D and

Customer Question

I have an Onan 5500 model 5.5HGJAB-901D and have a fault code of 14...any thoughts?
Ran for a day under load all was well. For that matter ran for eight years no problems 950 hrs on it, due an oil change but oil is still in the normal range(although at the lower third level within that normal range.
Submitted: 1 year ago.
Category: Small Engine
Expert:  JohnF2015 replied 1 year ago.
I have pasted here the information in regards ***** ***** fault code 14 on this machine. I hope it helps, I have also included a link below it that will get you to a service manual for the machine so that you can reference it whenever needed. I hope that this helps you.OVERFREQUENCY – FAULT CODE 14 WARNING Some genset service procedures present hazards that can result in severe personal injury or death. Only trained and experienced persons with knowledge of fuels, electricity, and machinery hazards should perform genset service. See Safety Precautions. Logic: Instantaneous Fault – Frequency greater than 70Hz Delayed Fault – Frequency greater than 66Hz, but less than 70Hz, for 3 continuous seconds Possible Causes: Genset loads, Inverter/Charger, engine governor function, fuel supply, air fuel mixture, exhaust system, choke, demand regulator, carburetor, generator drive system, generator windings, ignition, wire connections Diagnosis & Repair: 1. Verify that Last Fault is FC 14: Yes, continue diagnosis; No, troubleshoot actual last fault. 2. Measure AC current while running genset with vehicle loads: identify faulty or short cycling loads. 3. Determine battery charge rate (typical default is 80 percent): if adjustable reduce to 30 percent. 4. Measure genset load capability with shop load bank (derate for altitude and temperature as necessary). 5. Measure genset frequency and droop while running. 6. Measure AC frequency while changing engine rpm to determine if frequency response matches engine rpm response: repair damaged generator drive system as necessary. 7. Disconnect genset control P1 connector, verify P1 pins are fully inserted and inspect pin condition per PSB–676: insert, repair or replace pins as necessary. 8. Reconnect P1 connector and test run genset for fault occurrence: repair or replace pins in connector as necessary. 9. Check all grounds and neutral leads for looseness at battery, genset, inverter/converter; run genset on separate battery: tighten or replace terminals and leads as necessary. 10. Check air filter cleanliness; replace air filter as necessary. 11. Check for blocked or damaged exhaust system: repair or replace exhaust components as necessary. 12. Verify P1–29 (HGJAD, E, F Models; unused Hz select option prior to 2004) is not grounded: remove lead termination, tape and isolate. 13. HGJAD only – Run genset in Engine Run Only and externally excite field F1–F2 with 12 VDC or 24 VDC and measure main and quadrature winding AC output. 14. Non EFI – If the genset will not stay running measure genset frequency, quadrature winding and main winding voltages using Break-Out Tool 420–0603 and Instruction Sheet R1098. 15. All Gasoline Models A. Vapor lock may occur in high ambient temperatures: operate in ambients at less than 120°F; verify proper installation to prevent air recirculation; correct as necessary. B. Measure steady DC voltage at fuel pump while genset is cranking: repair wiring as necessary. C. Try to start genset on shop fuel supply: verify tank level and fuel line condition in vehicle. 11-11 16. All Gasoline Carburetor Models A. Verify carburetor altitude setting: readjust as necessary. B. Verify choke operation, setting, linkage, vacuum pull off assembly and sustain valve: readjust, repair or replace as necessary. C. Measure fuel pump pressure/flow: replace fuel filter or fuel pump as necessary. D. Inspect carburetor butterfly for binding: replace carburetor as necessary. 17. All Gasoline EFI Models A. Inspect throttle body for binding or damage: replace as necessary. B. Measure fuel pump pressure/flow: replace fuel filter, pressure regulator or fuel pump as necessary. 18. Propane Models A. When ambient temperatures are less than 40°F vapor-withdrawal Propane tanks should be at least half full to provide proper vaporization rate. B. Propane having more than 2.5 percent Butane will not vaporize in ambients at less than 32°F; use HD–5 grade Propane. C. Measure steady DC voltage at fuel solenoid while genset is running; repair wiring as necessary. D. Verify clear vent hose. E. Run genset on shop fuel supply; verify tank level and fuel line condition in vehicle. F. Check genset fuel lines for damage: replace fuel line as required. G. Measure regulator lock off pressure. 19. Check governor, actuator, linkage and spring for debris, damage and looseness: readjust and repair as necessary. 20. Measure field, quadrature and main winding resistance: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary. 21. Measure field, quadrature and main winding resistance to ground: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary. 22. Measure field, quadrature and main winding resistance to each other: clean slip rings, replace brushes, repair harness and replace rotor or stator as necessary. 23. Check brush alignment per PSB-682a. 24. Verify that spark plug cables are secure on spark plugs: reconnect or replace as necessary. 25. Inspect ignition kill leads in harness and at connector P1: repair or replace lead, terminal or pins as necessary. 26. Test Magnetos: A. Disconnect Connector P1. B. Connect positive(+) meter lead to chassis ground. C. HGJAA, D, E, F – Measure continuity to negative lead at pin P1–4 and P1–5: replace magnetos as necessary. D. HGJAB, C – Measure continuity to negative lead at pin P1–15 and P1–20: replace magnetos as necessary. 27. Measure spark plug gap: set gap or replace spark plugs as necessary. 28. Verify ignition spark condition. 29. Inspect spark plug cables, kill lead terminal at magneto and measure magneto air gap: replace terminals, set gap or replace magnetos as necessary. 30. Measure temperature of air intake and temperature rise across genset; remove blockage or prevent air recirculation. 31. Dealers contact Distributor for technical support, Distributors contact factory for technical support. https://www.cumminsonan.com/www/pdf/manuals/983-0501D.pdf Again, I hope that this helps you with your problem. Thanks