36kw unit power fluctuations under heavy load

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richard
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Thu Aug 08, 2019 1:11 am

No, nothing had been done to the unit that would have created the issue - just appeared. The only thing that remotely may have changed something we had some work done on drainage and they did put in some pipes in the vicinity of the gas line. About that time is when we noticed something amiss. However, I have adjusted the regulator and I'm sure the gas pressure is correct. Other than we have been getting a lot of rain, even a lot for Houston, and been plagued with very high humidity. Nothing else really. I changed the plugs thinking that may have been the issue but didn't help. So, I still think it appears to be fuel related, I'm thinking either throttle body / VR or something to do with the various bits of diaphragms etc feeding gas up to the mixer may have failed. I don't think it is the turbo, not too many hours and the oil has been kept fresh since new. I'm drawing at straws
Chris
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Fri Aug 09, 2019 9:40 am

Have you checked for any vacuum leaks at the various hoses? Make sure nothing is cracked, a vacuum plug hasn't rotted off, that kinda thing.
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richard
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Fri Aug 09, 2019 11:02 am

yes, checked them, all hoses look fine and the plug in the top of the engine is on and looks fine as well.
Chris
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Fri Aug 09, 2019 6:55 pm

Are you able to video the unit running and upload it to YouTube? If you post the link here it will auto-embed the video right into your post. You can make the video private if you want on YT so that it's not searchable.

A video might help us better understand what's going on here... I'm running out of ideas without seeing the unit :thinking:
Generac tech for over 12 years. I'm here to help!
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richard
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Sat Aug 10, 2019 4:04 pm

Chris,

See attached link to the video, I'm not too good at this new age technology but hopefully it shows what is going on. On a note, I pulled the plugs, they look fine, all look the same so they must be firing ok. When started today, seems to run fine at the exercise and when I shut off the utility line, runs fine until the a/c units start coming on. It'll run a 3.5 ton unit ok, but when one of the other units kick in it starts to stumble. I shut down the 4 ton unit and let the 1.5 ton unit come on while the 3.5 ton unit was on and it started to stumble - what you'll see in the video is just the 3.5 ton and 1.5 ton unit on. I'm afraid to run the 4 ton with the others as the surging gets pretty extreme and I'm afraid something will be burned out. One thing of note that may be of interest, once the generator got hot, and put the load on, there is what sounds almost like a knocking noise, seems to be coming from the generator head unit. Not sure if that was because of all the surging or if there is something in the generator/alt. portion that could be the culprit.


Thanks,

Richard

Chris
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Sun Aug 11, 2019 10:45 am

I can certainly see you have problems!

Do you have a timing light? I'm thinking it might be a good idea to see if you have spark on each wire during this!
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richard
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Sun Aug 11, 2019 8:58 pm

Will try in a few days, need to borrow a timing light - my kids apparently got away with mine at some point.
Chris
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Mon Aug 12, 2019 9:11 am

Hopefully this will shed some 'light' onto the problem :ahh: :tongue:
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richard
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Sun Sep 15, 2019 2:56 am

update - finally fixed. A few weeks ago I checked the coils. Two had high resistance on the low side (checking Ohms across the pins) so I changed them. The generator ran better but would still stumble at high load, albeit less than it was. Without having any idea what could still be amiss I got two more coils. Changed the last two coils on the unit today (now all four are new) and it seems fixed now. We are hot down here, close to 100, and the unit ran fine. Let it run for about three hours with various loads coming and going and the unit was able to keep up. Voltage in the house fluctuated very little during the test - usually when an a/c or some other large draw kicked on but then quickly stabilized. So, it'll keep up with the a/c units so I call this fixed. Would have never thought I'd have multiple coil failures on a generator that has less than 500 hours on it. Thanks for the advice/help.
Chris
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Sun Sep 15, 2019 10:20 am

I'm glad to hear that you have fixed it! If you ever need any more parts in the future, just let me know. :cool:
Generac tech for over 12 years. I'm here to help!
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