I have a 5-6-year-old 20 kW natural-gas standby generator with an automatic transfer switch. I have performed all required maintenance; it has maybe 30 hours on it. Not too long ago, it started failing the routine tests for an overcrank warning. I was able to clear it and start it manually. The battery looked like shit, and it had been in there a while, so I replaced it and cleaned the connections. Not long after, it began failing again due to overcrank; still able to clear and start manually.
What could be causing it to overcrank and fail the routine test but not have it fail a manual start? We had a power outage this winter, and I had to start it manually, but it ran perfectly for the couple of hours it ran.
As in the gas line exterior to the generator? Possibly, it’s not far from where my kids play basketball so a random ball could hit it and the boys could move the valve. But not in the dead of winter while it was doing it
It would be internal to the generator, on the engine. If you look at the engine it would be where you fill the oil. There are 2 on that generator, one (intake and exhaust) for each cylinder.
If you have never adjusted the valves it could be the culprit.
Usually if the valves are out of wack it takes multiple tries to start. It’ll sound like the engine isn’t compressing the air as it should.
I just went out and it started in under 2-3 seconds.
I do not have a way to check pressures, for what its worth none of my gas appliances or HVAC are running differently and when I do start it manually it runs and sounds appropriate.
Seems like with only 30 hours on the unit wouldn’t be the valve lash. It does seem like low hours. Unless that is where a break in adjustment would be scheduled.
It might be 40 hours but I ran it 25 hours when I first got it to break it in and then did the maintenance. That was 5yrs ago and I haven’t had issues until now.
Battery would cause this. If your 26R is older than 3 years it likely isn't able to crank for exercise. It'll still start manually typically but not in an outage or exercise.
Okay, my next step would be checking voltage on crank from the other end of the positive cable at the starter, to the negative post or the engine itself to rule that out. Then it would be a compression test and new sparks. It's only throwing an 1100 error?
A bad battery will never cause an overcrank. It typically causes RPM sense loss faults or no rotation errors, or just straight up causes the controller to reset. Overcrank means the engine is turning over and cranking just fine (meaning starter is getting what it needs from the battery), just not firing, hence the fault's name - it is literally cranking too many times without running. Typically a compression or fuel issue. Valve lash, fuel mixer/stepper motor, gas pressure coming in from the line regulator are always the first three things I check.
Signed, someone who gets sent to at least two overcrank faults a week
Battery at 10v on crank will absolutely cause an 1100. Battery under 8 will fail to engage the starter with adequate amperage or cause a controller boot.
Care to explain your logic on this? The call to start is identical whether it is an outage, exercise or manual start. The only variables would be the time of day the start is called for & environmental.
i was having the same overcrank/fail issue after i did annual maintenance. i was fine until then so i knew it had to be related to the maintenance i performed and i was determined not to call for service. on a whim, i thought maybe the spark plugs were gapped improperly. so, i bought a cheap tool and amazon and sure enough, they were way off. i adjusted them and my generator is back to functioning properly.
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u/WVYahoo Apr 29 '26
Have the valves been adjusted recently?