Specifications
| Fuel | natural gas |
|---|---|
| Standby power | 250 kW |
| Standby kVA | 312 |
| Prime power | 180 kW |
Maintenance & consumables
for the Cummins/Onan GTA855| Item | Spec | Capacity | Part # | Interval | |
|---|---|---|---|---|---|
| Air filter | IMPCO High Altitude, Low Pressure Gas System (Std) | — | find | ||
| Fuel filter | — | find | |||
| Oil filter | Combination Full Flow/ By-Pass LF 3000 Filter Capacity – U.S. gal. | — | find | ||
| Belt | — | find | |||
| Coolant | — | ||||
| Oil | Multi-viscosity or straight weight single viscosity NATURAL GAS ENGINE OIL that meets Mil-2104A(CB), Mil-2104B (CC), Mil-2104C (CD/SC), CE and CF-4 specification. Ash Content between .15 and .85 of one percent. | 3.8 litre | — |
Common questions
What is the power rating of the Cummins/Onan GTA-855?
The Cummins/Onan GTA-855 is rated 250 kW standby (312.0 kVA).
What engine does the Cummins/Onan GTA-855 use?
The Cummins/Onan GTA-855 is powered by the Cummins/Onan GTA855 engine.
What fuel does the Cummins/Onan GTA-855 use?
The Cummins/Onan GTA-855 runs on natural gas.
Troubleshooting
9Symptoms & remedies
| Symptom | Cause | Remedy |
|---|---|---|
| No spark at the spark plug. | (Refer to ignition System.) | Ignition firing circuit grounded. Caution: When checking ignition, avoid arcing of electrical connections in a gaseous state. Altronic faulty. Ignition transformers faulty. Incorrect or defective spark plugs. Water in cylinder or on plug. Safety switch failed - closed. Ignition switch failed - closed. ‘instrument Panel grounded. Timing Disc improperly gapped or aligned. Altronic ground wire loose, no ground of alternator case or pickup block. Check (P) lead for proper (60-70V) voltage. (40V and below is bad.) Check spark plug primary leads for proper voltage. Bad wiring harness. Check Altronic capacitor for correct charging. Check ignition timing. Remove and inspect transformers for cracks, moisture or broken connections. Inspect transformer well in cylinder head for coolant leakage or rain water. Check continuity of transformer. Check for recommended type. Check spark plug gap. Check for damaged insulators. Check for shorted electrodes. |
| Insufficient or no gas supply. | Gas shut-off closed. Note: If no gas shut-off is installed between a faulty valve and main gas line regulator, do not attempt to remove valve until local gas company has been notified and a representative is present to approve removal. Gas valve open, low gas pressure to Thermac, engine running. Gas valve open, low gas pressure from Thermac, engine running. Low gas pressure. Thermac adjusted full open, engine running. Note: Thermac should not be operated in full open position. Re-position adjusting screw to minimum of 10 turns from full open position. Check manual valve; if closed, open slowly. Check electric or Sentinel valve with manual re-set. Re-set to run. Check electric valve for proper voltage being supplied to open. If valve fails to open with proper voltage present, solenoid, or complete valve must be replaced. Bad in-line gas filter. Consult local gas company for gas supply pressure. Request gas company to supply minimum 10 inches H2O if supply line is of recommended size. lf supply fine is not of recommended size, an increased pressure to maximum of 20 inches of HzO may be required. Pressure test prior to starting engine indicate 10 inches HzO minimum of gas from main line regulator to Thermac. If static pressure minimum of 10 inches of H2O existed, adjust Thermac to 5 inches H2O with engine idling. Request local gas company to remove orifice and spring from main line regulator to check if they are proper size. Inspect supply line for recommended size and to assure no leakage is evident. With the assistance of local gas company, inspect piping valves, regulator and fittings for obstructions. | |
| Excess gas. | Note: Excess gas can be detected by odor, indicating a leak or flooding condition. Restricted air intake. Piston ring or valve teakage. Stop engine, raise supply line gas pressure from main line regulator to 15 inches H20. Restart engine. Adjust Thermac to provide 5 inches HzO gas pressure. If unable to maintain 5 inches HzO, stop engine, raise static gas pressure in one inch water column increments until 5 inches of HzO Thermac to carburetor gas pressure can be maintained. Do not exceed 20 inches H2O supply line gas pressure with engine stopped. If 5 inches Hz gas pressure cannot be maintained, a supply probiem exists. Contact local gas company. Inspect and adjust gas pressure regulator valves. Check Thermac pressure reducing valve for proper operation and controllability. Check Thermac atmospheric vent for gas leakage. Check Impco carburetor air/gas valve diaphragm for leakage at seating area. Warped diaphragm plate. Check gas power mixture adjustment valve for correct setting. Remove carburetor cover and inspect for broken air valve spring. Remove and inspect air cleaners. Inspect air piping. | |
| Insufficient air. | (Refer to Air System.) | |
| Unbalanced compression pressure. | Hard starting - rough idle. Note: Excess gas can be detected by odor, indicating a leak or flooding condition. Restricted air intake. Piston ring or valve teakage. Stop engine, raise supply line gas pressure from main line regulator to 15 inches H20. Restart engine. Adjust Thermac to provide 5 inches HzO gas pressure. If unable to maintain 5 inches HzO, stop engine, raise static gas pressure in one inch water column increments until 5 inches of HzO Thermac to carburetor gas pressure can be maintained. Do not exceed 20 inches H2O supply line gas pressure with engine stopped. If 5 inches Hz gas pressure cannot be maintained, a supply probiem exists. Contact local gas company. Inspect and adjust gas pressure regulator valves. Check Thermac pressure reducing valve for proper operation and controllability. Check Thermac atmospheric vent for gas leakage. Check Impco carburetor air/gas valve diaphragm for leakage at seating area. Warped diaphragm plate. Check gas power mixture adjustment valve for correct setting. Remove carburetor cover and inspect for broken air valve spring. Remove and inspect air cleaners. Inspect air piping. | |
| Engine Will Not Idle Properly. | Uneven firing of cylinders. (Refer to Ignition System.) Improper combustion. Weak spark at spark plug. Incorrect or defective spark plugs. Incorrect fuel mixture. | |
| Engine Will Not Idle Properly | Unbalanced compression | Check individual cylinder compression |
| Engine Fails To Operate Properly Under Load; Has A Miss Or Vibration | Ignition system functioning improperly | |
| Missing magnet on Timing Disc | Check for recommended type |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Available documents
Engine spec — CUMMINS G495 G743 G855 GTA743A GTA743B GTA855 G1710 GTA1710 Operation and Maintenance Manual (2) (Cummins/Onan)