22kW 2.4L Mitsubishi Govenor Fault Alarm

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geoffleach
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Mon Feb 18, 2019 12:31 pm

Generac 22kW 2.4L Mitsubishi 1150 hours

Governor Sensor Fault Alarm raised during rainstorm. Reset the condition, has not re-occurred.

What action, if any, can I take to prevent this from happening again?

Thanks
Chris
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Mon Feb 18, 2019 1:45 pm

I would advise comparing the alarm log to the run log to see when this alarm occurred. It would give you some insight into when it actually happened, and if the unit had been sitting like that for a while.

Normally this is an issue with governor movement. Basically the governor has 2 systems. First is power to drive the motor which moves the throttle plate and second is the feedback wiper which tells the controller where in its movement the throttle plate actually is. Generally if the controller expects to see the throttle move and it doesn't, you'll get the Governor Fault. I've seen this happen for no apparent reason and never come back as well. I've also heard of people with fuel issues that might cause a backfire or other stall condition to occasionally throw this fault as well.

What does the fuel installation look like?
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geoffleach
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Mon Feb 18, 2019 4:15 pm

The gen is about 15 feet from a 250 gal propane tank. The regulator is not shared with anything else.
Chris
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Mon Feb 18, 2019 4:36 pm

How large is the line and what length between the secondary fuel regulator and the generator's inlet?
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geoffleach
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Mon Feb 18, 2019 9:35 pm

The line is 3/4". Not sure what the secondary fuel regulator is, so guessing. Is this the "Fuel reg" #35 on the Group E page? In that case, it's inside the gen housing.

I notice that in the section "Fuel System" there appear to be two options for Propane/LP. I'm assuming that what I have is a "Propane Vapor Withdrawal" system. The info there suggests that low supply tank volume and low ambient temp could give trouble. When the problem occurred, we were at 25% of capacity in the supply tank, the ambient temp was about 35, and it was raining heavily.
Chris
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Tue Feb 19, 2019 9:09 am

Hmm, are you able to post a couple pictures of the install? That may shed some light on what's going on.
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geoffleach
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Tue Feb 19, 2019 6:23 pm

Here are a couple of shots. If not useful, please advise.
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Chris
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Tue Feb 19, 2019 7:57 pm

It's a little hard to tell, but it appears there's a section of much larger than 3/4" pipe right at the generator, which is a good thing.

I would probably keep an eye on it over the next few weeks as it exercises and make sure you don't hear anything out of the ordinary as far as stumbling during starting etc.

The low tank volume will certainly cause issues too. 250 gal is probably the bare minimum for that sized generator.

With that many hours on it, has it had the plugs replaced?

These are all long shots for a governor error, but if the governor is operating normally and there's no loose connections, I try to look to see if anything else looks off...
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Birken Vogt
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Wed Feb 20, 2019 10:47 am

I have seen gov. faults on these a fair bit as well. The last one has some issue that is causing the governor to bounce all over the place so I suspect the high activity caused it to wear out prematurely. But the customer has not had me fix that yet. In all cases, replacing the throttle body has done the trick. It is easy but not cheap.

The controller seems hyper sensitive to any issue. In all cases the generator was still running good enough. I wish the controller would let it get a little worse before throwing a fault.
geoffleach
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Wed Feb 20, 2019 4:48 pm

Plugs replaced at 891 hours (10/10/16). Interesting fact re the tank size. Here's a piece pf data that might be significant. At the time that the fault happened we were using our hot water heater: Takagi T-H3-DV-LP, 199,000 BTU.

Thanks for the consideration. I'll post further if there's any change.
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