Generators
Sort the complaint first: won't crank, cranks but won't start, starts then dies, or runs but no power.
The short version
- Won't crank: battery and connections at the generator.
- Starts then dies: check the oil level first. Low oil shuts it down on purpose.
- Runs but no power: generator breaker on the unit, then the transfer switch.
- Read the fault code it flashes and look it up for that model.
- Cranks but won't start with fuel and oil good: check fuel getting to the carb or injector, and the spark.
- Hasn't run in months and surges or won't stay running: stale fuel and a gummed-up carb.
- The exhaust is carbon monoxide. Check the exhaust system for damage or leaks and make sure the CO alarm works before the unit goes back to the customer.
On the job
- Fuel above a quarter tank. The generator pickup is higher than the engine's.
- Read the code: STOP/PRIME once, count blinks (tens, pause, ones). Code 36 engine stopped, 4 over crank, 32 slow crank, 2 oil, 13/15 under voltage or frequency = overload.
- Fuel at the carb (crack the line while cranking), spark with an inline tester, then a short shot of starting fluid: fires and dies means the carb.
- Oil level and viscosity for the weather. Battery 450 CCA minimum, clean cables.
- Run it under load 30 minutes a month.
Numbers
- Fuel pickup: about 1/4 tank
- Oil (QG 4000): 1.8 qt, SAE 30 above 32°F, 15W-40 for 10 to 100°F
- Derate: 3.5% per 1,000 ft, 1% per 10°F above 77°F
Shop tip
On motorhomes, the generator's fuel pickup sits higher in the tank. Under about a quarter tank it can't get fuel. That's by design so it can't run the coach dry.
Try it on a service call
Put the lesson to work on a hands-on troubleshooting case.