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. Reset hour meter to last-service reading
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