HomeFirmanFirman T04073

Firman T04073 Generator Set

The Firman T04073 is a Gasoline/LPG/NG generator set. It is available at 120/240 V, single-phase and 60 Hz. It holds about 0.6 L (0.2 gal) of oil. An integrated tank holds 19 L (5.0 gal).

0.6 L
Oil capacity
0
Document types

Service parts for the T04073

Grouped by system, with how many of each the parts manual calls for.

Air intake

1 required
336713526Air filtersee priceeBay

Ignition

1 required

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

FuelGasoline/LPG/NG
Frequency60.0 Hz
Oil capacity0.6 L
Voltage options120/240 V
PhaseSingle
Power factor1
Fuel tank19.0 L

Maintenance & consumables

ItemSpecCapacityPart #Interval
Air filterAir Cleaner Bracket336713526 eBay
Battery12V sealed lead acid 7.5AH, 151x65x97mm
OilFIRMAN SAE 10W-30 API SL0.6 L100 hr
Spark plugelectrode gap 0.020-0.024 in. (0.5-0.6mm)330723001 eBay $9.99

Service intervals

11
ItemActionHoursMonthsNotes
Engine OilCheck25 hrFirst service — check oil level, initial 25 hours
Fittings/FastenersCheck50 hrFirst service — initial 25 hours
Air FilterClean50 hrclean, replace if necessary
Fuel LineCheck50 hrcheck for leakage, retighten or replace gasket if necessary
Spark PlugCheck50 hrcheck condition, adjust gap and clean
Engine (fuel hose)Check100 hr12 mocheck fuel hose for cracks or other damage, replace if necessary
Engine OilChange100 hrchange every 100 hours; for new engine change after 25 hours
Exhaust SystemCheck100 hr12 mocheck adjust valve clearance, clean combustion chamber
Spark PlugReplace100 hr12 mo
Fuel Tank StrainerClean250 hrclean fuel tank strainer, replace if necessary
Spark Arrester ScreenClean250 hrclean/replace if necessary

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

4
TypeItemValueUnitCondition
ClearanceExhaust Valve Clearance0.004-0.006in. (0.10-0.15 mm)
ClearanceIntake Valve Clearance0.004-0.006in. (0.10-0.15 mm)
GapSpark Plug Electrode Gap0.020-0.024in.
PressureNatural gas fuel pressure range7-11 inches water column (0.25-0.40 psi)(13-20mm mercury)(1.7-2.7 kpa)

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

FluidGradeStandardAmbientCapacityNotes
Engine oilSAE 10W-30 API SLAPI SL or higher0.6 LOther high-quality detergent oils API SL or higher acceptable; full synthetic 5W-30, 5W-30, 10W-40, 10W-30 by temperature chart
FuelUnleaded gasoline min 87 octane, max 10% ethanol19.0 L5.0 US Gallons; at altitudes over 5000ft, min 85 octane acceptable

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

7
Add Engine Oil maintenance

⚠ Do not attempt to crank or start engine before properly filled with oil

Tools: oil funnel

  1. Place generator on flat, level surface
  2. Clean area around oil fill and remove oil fill cap/dipstick
  3. Wipe dipstick clean
  4. Using oil funnel, slowly pour oil into fill opening until it reaches upper limit H mark on dipstick
  5. Replace oil fill cap/dipstick and fully tighten
  6. Check oil level prior to each use or at least every 8 hours of operation
Air Filter Maintenance maintenance
  1. Carefully remove foam air filter element and wash with liquid detergent and water only, squeeze dry in clean cloth
  2. Saturate foam air filter element with clean engine oil and squeeze in clean cloth to remove excess oil
  3. Reinstall clean or new air filter element
Change Engine Oil maintenance

⚠ Avoid prolonged or repeated skin contact with used motor oil

  1. On level surface drain oil into suitable container by removing drain plug and oil filler cap while engine is warm
  2. Reinstall drain plug and fill engine with oil until it reaches HIGH(H) level on dipstick
Inspect Muffler and Spark Arrester maintenance

Tools: wire brush

  1. Inspect muffler for cracks, corrosion, or other damage
  2. Remove screws securing spark arrester and remove from muffler
  3. Carefully remove carbon deposits from spark arrester screen with wire brush
  4. Replace spark arrester if damaged, using only FIRMAN OEM parts
  5. Position spark arrester in muffler and attach with screws
Long Term Storage maintenance

⚠ Fuel and vapors are extremely flammable

  1. Treat any stored fuel with fuel stabilizer
  2. When storing with gasoline in tank, operate engine 5-10 minutes to circulate treated fuel
  3. No need to drain gasoline if fuel stabilizer added
  4. If draining fuel tank, run generator outdoors until it stops from lack of gasoline
  5. Always turn main fuel selector switch to OFF prior to storage
  6. Allow generator to cool before cleaning and storage
  7. Change oil
  8. Remove spark plug boot and spark plug, pour about one teaspoon of engine oil through spark plug hole, pull recoil starter several times
  9. Cover generator and store in clean, dry place out of direct sunlight
Spark Plug Maintenance maintenance

Tools: spark plug wrench

  1. Remove spark plug boot
  2. Remove spark plug using provided wrench
  3. Inspect spark plug for damage and clean with wire brush before reinstalling, replace if damaged
  4. Adjust electrode gap to 0.020-0.024 in. (0.5-0.6mm)
  5. Seat spark plug in position and thread by hand to prevent cross threading
  6. Tighten plug with provided wrench and put spark plug boot back on
Battery Replacement repair
  1. Remove spark plug boot from spark plug
  2. Remove nut and bolt from negative post first, then positive post
  3. Loosen and remove cap screws and nuts on battery holding bracket
  4. Remove battery and recycle
  5. Install new battery: 12V sealed lead acid 7.5AH, 151x65x97mm
  6. Connect red positive battery cable to battery first
  7. Connect black negative battery cable to battery second
  8. Cover posts with boots provided
  9. Install spark plug boot onto spark plug

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

What fuel type does the Firman T04073 take?

The Firman T04073 runs on Gasoline/LPG/NG.

What air filter fits the Firman T04073?

The Firman T04073 uses air filter part number 336713526.

Troubleshooting

7

Symptoms & remedies

SymptomCauseRemedy
Engine is running, but no AC output is available.1. Circuit breaker is open. 2. Fault in generator. 3. Poor connection or defective cord set. 4. Connected device is bad.1. Reset circuit breaker. 2. Contact authorized service facility. 3. Check and repair. 4. Connect another device that is in good condition.
Engine runs good at no-load but “bogs down” when loads are connected.1. Short circuit in a connected load. 2. Engine speed is too slow. 3. Shorted generator circuit.1. Disconnect shorted electrical load. 2. Contact authorized service facility. 3. Contact authorized service facility.
Engine will not start; starts and runs rough or shuts down when running.1. Fuel selector switch set to OFF (O) position. 2. Low oil level. 3. Dirty air cleaner. 4. Out of gasoline. 5. Stale gasoline. 6. Spark plug wire not connected to spark plug. 7. Bad spark plug. 8. Water in gasoline. 9. Flooded. 10. Excessively rich fuel mixture.1. Set fuel selector switch to “GAS” or “LPG/NG” position. 2. Fill crankcase to proper level or place generator on level surface. 3. Clean or replace air cleaner. 4. Fill fuel tank with gasoline. 5. Drain fuel tank and carburetor; fill with fresh gasoline. 6. Connect wire to spark plug. 7. Replace spark plug. 8. Drain gas tank and carburetor; fill with fresh gasoline. 9. Wait 5 minutes and re-crank engine. 10. Contact authorized service facility.
Engine lacks power.1. Load is too high. 2. Dirty air filter.1. Don't Overload Generator 2. Replace air filter.
Engine“hunts”or falters.1. Carburetor is running too rich or too lean. 2. Clogged or dirty fuel filter. 3. Clogged or dirty fuel filter. 4. Clogged spark arrester.1. Contact authorized service facility. 2. Clean or replace fuel filter. 3. Clean or replace fuel filter. 4. Clean or replace spark arrester.
Engine shuts down when running.1. Out of gasoline or LPG/NG. 2. Dirty air cleaner. 3. Low oil level. 4. Clogged or dirty fuel filter.1. Fill fuel tank with gasoline or replace LPG cylinder / check NG supply. 2. Clean or replace air cleaner. 3. Fill crankcase to proper level or place generator on level surface. 4. Contact authorized service facility.
Engine shuts down and yellow CO fault light blinking.1. CO system fault1. Contact authorized FIRMAN service facility.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.

Parts

20
Part #DescriptionQtySystem
330723001Spark Plug1Spark plug eBay $9.99
336713526Air Cleaner Bracket1Air filter eBay
336723551Gasket, Carburetor1Gasket eBay $15.99
336723552Gasket, Air Cleaner2Gasket eBay
336723567Air Cleaner Set1Air filter eBay
336723569Element, Air Cleaner1Air filter eBay
336723614Starter Motor Assembly1Starter eBay $49.99
336728301Recoil Starter Knob1Starter eBay
340713007Seal, Oil2Seal eBay
340713011Gasket, Cylinder Head1Gasket eBay
340715501Muffler Gasket2Gasket eBay
340715510Starter Assy1Starter eBay
336713529Holder, Spark Arrester1Service part / kit eBay
336713533Muffler Assembly1Service part / kit eBay
336713590Charger1Service part / kit eBay
336713820Battery1Service part / kit eBay
336723609Ignition Coil1Service part / kit eBay
340415504Carburetor1Service part / kit eBay
340715500Arrester, Spark1Service part / kit eBay
340715505Control Module&vf Module1Service part / kit eBay

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

RatingLoadL/hgal/h
Standby1.70.45

Available documents

Owner's manual (FIRMAN Power Equipment)
Full service, cheapest listings

Priced items from this model's own parts manual.

Spark plug 330723001$9.99
1 priced item$9.99