Annual Generator Maintenance SOP

Purpose

Define annual maintenance for standby generators. Generators that aren't maintained don't start when needed - failure rate jumps from <5% to 30-40% for un-serviced units.

Scope

Residential standby generators 10-26kW, gasoline/natural gas/propane. Annual service. Excludes major repairs (separate scope).

Prerequisites

• Service kit: oil, filter, air filter, spark plugs, fuel filter (if applicable)
• Test equipment: digital multimeter, load tester
• Tools: oil pan, funnel, torque wrench, sockets
• 2-3 hours per residential unit
• Customer notification (you may be running the unit)

Procedure

Step 1: Visual inspection (10 min)

1. Walk around generator, check:

• Visible damage, rust, vibration cracks
• Mounting bolts secure
• Battery terminals clean + tight
• Wiring intact (no fraying, chewing by rodents)
• Exhaust pipe secure
• Air intake clear
• Drainage adequate around unit (no flooding)

1. Inspect concrete pad for settling or cracking

Step 2: Test in standby mode (10 min)

1. Note current status (auto-test history if available)
2. Verify week-test settings still set
3. Read run-hour total (write down - compared to last service)
4. Check for any error codes

Step 3: Battery service (15 min)

1. Measure battery voltage with multimeter

• 12.6-12.8V at rest = good
• 12.2-12.5V = marginal, may need replacement soon
• < 12.0V = replace

1. Clean terminals (corrosion + grease)
2. Apply terminal protectant
3. Verify battery charger output (13.6-13.8V typical)
4. Replace battery if more than 2-3 years old + showing weakness

Step 4: Oil + filter change (30 min)

1. Run generator 5 minutes (warms oil)
2. Shut down
3. Place oil pan under drain plug
4. Remove drain plug; drain completely
5. Replace drain plug with fresh gasket
6. Remove oil filter; lubricate new filter gasket with fresh oil; install
7. Add fresh oil (manufacturer-spec quantity + type)
8. Check level with dipstick (cold reading)

Step 5: Air filter (10 min)

1. Inspect air filter
2. Tap out loose debris
3. Replace if clogged (typical: every 200 hr or annual)
4. Reinstall filter housing

Step 6: Spark plug + ignition (15 min) - applicable to gas/propane units

1. Remove spark plug(s) - wear gloves, hot if recently run
2. Inspect: gap, electrode condition, color (light tan = healthy combustion)
3. Replace per manufacturer interval (typical: every 200-400 hours OR 2-3 years)
4. Gap to spec
5. Apply anti-seize to threads sparingly
6. Hand-tighten + final torque to spec

Step 7: Fuel system (15 min)

For natural gas:

• Inspect supply line for kinks, damage
• Check for soap-bubble leaks at fittings
• Verify shutoff valve operates

For propane:

• Check tank fuel level
• Inspect regulator
• Check supply line

For gasoline (portable):

• Drain old gas, refill with stabilized fuel
• Clean carburetor if needed

Step 8: Coolant check (5 min) - liquid-cooled only

1. Check coolant level + color
2. Top off if low (50/50 antifreeze/water)
3. Replace coolant per manufacturer interval (every 5 years typical)

Step 9: Test run + load test (30 min)

1. Manual start; verify smooth running
2. Check voltage (240V ± 5%) + frequency (60 Hz)
3. Engage transfer switch (simulate outage)
4. Monitor load + voltage stability
5. Run under load 15-20 minutes
6. Restore utility; transfer switch returns
7. Generator runs cooldown 1-2 min, shuts off

Step 10: Update + reset (10 min)

1. Update next-service date in maintenance log
2. Update mobile app firmware if available
3. Record the hour-meter reading in the log. Do NOT reset it. The meter is cumulative, and subtracting last year's reading from this one is the only way you or the next tech gets hours-since-last-service, which is what Step 2 and the service record depend on
4. Provide service record to customer

Step 11: Customer briefing (10 min)

1. Review findings (any issues found, recommended actions)
2. Confirm next-service date
3. Discuss any optional upgrades (battery replacement, fuel line, etc.)
4. Provide written service report

Acceptance criteria

• Generator passes load test
• Battery voltage adequate (12.6V+ resting)
• Oil + filter changed
• Air filter inspected/replaced
• Plug(s) inspected/replaced if needed
• Fuel system leak-free
• Coolant level + condition OK (liquid-cooled)
• Customer signoff
• Service record updated

Common pitfalls

• Skipping load test: generator runs without load but fails under load
• Not changing oil annually: oil degrades; sludge builds up
• Skipping plug inspection: dirty plug = misfiring, hard start
• Not noticing pad settling: misaligned exhaust, vibration damage
• Ignoring battery warnings: dead battery = no auto-start
• Not testing transfer switch: relay sticks
• No record-keeping: customer thinks you skipped something

Service contract value

Annual contracts:

• Predictable revenue
• Customer remembers you when failure happens (call you, not competitor)
• Catch issues before failure
• Higher customer LTV (typically 2-3x non-contract)
• Easier scheduling (book all customers same season)

Target: 60-80% of new install customers convert to annual contract.

Documentation

Each service includes:

• Service date
• Hours run since last service
• Battery voltage
• Voltage + frequency tested
• Parts replaced
• Recommended future work
• Customer signature

Records retained 7+ years.

When NOT to do annual service

• Generator < 6 months old + has had factory service
• Generator with active warranty issue (refer to manufacturer/dealer first)
• Customer in middle of outage (do after restoration)

References

• Manufacturer service manuals (Generac, Kohler, etc.)
• NFPA 110 (Standby Power Systems)
• Manuall internal: Whole-House Standby Generator Installation SOP