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General Category => General Discussion => Topic started by: blackcat on December 07, 2021, 10:56:01 AM

Title: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 10:56:01 AM
Our whole house natural gas Generac which is 16 years old is not starting. Anyone have any experience with these older machines?  I've installed new spark plugs, oil is at the correct level, adjusted the valves, removed the filter and choked the intake manifold, sprayed an engine starter in both chambers and all I got was a back fire. I'm going to check the plug gap to make sure it is spot on but I'm starting to think it is a fuel issue.  Also have spark to both plugs.  Any ideas?
Title: Re: Generac 15KW Natural Gas Problem.
Post by: RinkRat II on December 07, 2021, 11:23:21 AM

    Possible meeces chewed through a wire or two. If as you say no fire when you put starting fluid in it, possible electric snafu.  Possible air in the Nat Gas line into the regulator.  My$.02

     Paul B  :boozing:
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 12:01:31 PM
    Possible meeces chewed through a wire or two. If as you say no fire when you put starting fluid in it, possible electric snafu.  Possible air in the Nat Gas line into the regulator.  My$.02

     Paul B  :boozing:

Looks like the regulator is rebuildable or at least there are specific parts that can be replaced. Of course getting to the thing is a nightmare. No evidence of rats or mice as the wires all look OK. And of course there is only one applicable Youtube video that I can find for this machine with a suggestion of tapping the gas regulator. NG on that tapping.

Thanks.
Title: Re: Generac 15KW Natural Gas Problem.
Post by: Iron Cross Junction on December 07, 2021, 12:53:03 PM

We have a propane 17kw Generac.

About the only problem we have experienced that sounds similar to yours was one that may not affect natural-gas models ... tho "gas is gas."  Sort of.   :rolleyes:

I'll see if I can find the pix to make this less babblespeak, but mud daubers -- https://hgic.clemson.edu/factsheet/mud-daubers/ -- had blocked a valve where the gas line connects to the generator.  Could not see this without getting on ground and loooking up.

Good luck on finding the cause.  Generators are great peace of mind, albeit an expensive way to repicate the grid.  :wink:

Bill
Title: Re: Generac 15KW Natural Gas Problem.
Post by: slowmover on December 07, 2021, 01:35:08 PM
My battery was dead due to a charger failure
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 03:17:31 PM
We have a propane 17kw Generac.

About the only problem we have experienced that sounds similar to yours was one that may not affect natural-gas models ... tho "gas is gas."  Sort of.   :rolleyes:

I'll see if I can find the pix to make this less babblespeak, but mud daubers -- https://hgic.clemson.edu/factsheet/mud-daubers/ -- had blocked a valve where the gas line connects to the generator.  Could not see this without getting on ground and loooking up.

Good luck on finding the cause.  Generators are great peace of mind, albeit an expensive way to repicate the grid.  :wink:

Bill

Thanks Bill,  I think that the problem is a fuel issue but no dirt daubers around the fuel regulator. The hoses are original so that might be an issue or the fuel solenoid might be stuck though I've hit it a few times as that was suggested elsewhere.   I found a Generac forum and just posted a question to them, so I will see what happens. I don't want to start changing parts without some guidance because the fuel regulator is $200+bucks which is OK if that solves the problem.  Hurricane season is a ways off, so now is the time to get it fixed. 
Title: Re: Generac 15KW Natural Gas Problem.
Post by: RinkRat II on December 07, 2021, 03:28:21 PM

    Possible fuel solenoid stuck shut or the wiring for same not allowing voltage thru. Fuses in control panel good?
     
      Another $.02

      Paul B  :boozing:
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 03:34:21 PM
    Possible fuel solenoid stuck shut or the wiring for same not allowing voltage thru. Fuses in control panel good?
     
      Another $.02

      Paul B  :boozing:

Yes, the fuses are good but I haven't checked the power to the solenoid. A heavy duty solenoid cost $60 bucks, so I may change it to that one even though this one has been fine all these years. Or I just buy a new fuel regulator which comes with a new solenoid:

https://shop.gentekpower.com/collections/generac-parts-accessories-free-shipping/products/generac-0d8631-dual-fuel-regulator-for-air-cooled
Title: Re: Generac 15KW Natural Gas Problem.
Post by: RinkRat II on December 07, 2021, 03:43:35 PM

       I would also think you should hear or feel the solenoid operate when you power up. May need a trusty assistant for that.

       Paul B  :boozing:
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 03:56:17 PM
       I would also think you should hear or feel the solenoid operate when you power up. May need a trusty assistant for that.

       Paul B  :boozing:

I just checked the voltage to the solenoid; 12.85 volts. That unit is right below the starter button but I don't hear anything when the button is hit and there is a slight lag between the engagement of the button and the spinning of the starter. Just four screws and it maybe possible to get the solenoid out without removing the fuel regulator.
Title: Re: Generac 15KW Natural Gas Problem.
Post by: RinkRat II on December 07, 2021, 03:59:14 PM

  Sounds like a plan. When did the genset run last?

    Paul B  :boozing:
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 04:05:12 PM
  Sounds like a plan. When did the genset run last?

    Paul B  :boozing:

Honestly, I don't know. It was set to automatically run once a week to keep the battery charged and it may have run a month ago but I'm not sure. I know it was OK during this past hurricane season as I did check it in September.
Title: Re: Generac 15KW Natural Gas Problem.
Post by: Gliderjohn on December 07, 2021, 04:26:35 PM
It would have thrown a caution light or red light if it had detected any problems during the weekly run.
GliderJohn
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 04:36:23 PM
It would have thrown a caution light or red light if it had detected any problems during the weekly run.
GliderJohn

No caution lights so it must not be an electrical issue?
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 04:46:43 PM
I did a quick search for "generac 15kw lpg won't start" and got a bunch of hits on older units.  They might be your exact model, but the theory should be the same.

A couple of those posts said that the units like certain spark plugs but I replaced the old one with the same Autolite plugs. I'll pull the solenoid tomorrow and see what kind of shape the plunger is in and if it's stuck that might be the answer.

Title: Re: Generac 15KW Natural Gas Problem.
Post by: SSGG Geezer on December 07, 2021, 05:10:20 PM
I had some electricians dissing Generac's control board and wiring about 12 years ago so if you can get a wiring diagram with expected voltages at what time and state, that would be a place to start, but the Solenoid is the first place. And your battery voltage may be a little low to operate it if the voltage sags when you try to start it.  Solenoids and thermocouples always gave me issues on my instant on hot water heaters so it sounds like supply line issues.  Good luck and let us know what you find out.
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 05:27:59 PM
I had some electricians dissing Generac's control board and wiring about 12 years ago so if you can get a wiring diagram with expected voltages at what time and state, that would be a place to start, but the Solenoid is the first place. And your battery voltage may be a little low to operate it if the voltage sags when you try to start it.  Solenoids and thermocouples always gave me issues on my instant on hot water heaters so it sounds like supply line issues.  Good luck and let us know what you find out.

I have the wiring diagram for this model and yes, the new models are better in terms of the control panel. The onboard battery charger is a known problem as they can blow up the battery which happened to mine, like it cracked the battery. It is recommended to disconnect that feature and just use a battery tender, which I just found out today.

The Generac forum tech said I have the wrong plugs installed even though it's had Autolite plugs in there for years, but I will pick up a pair of the recommended plugs tomorrow.
Title: Re: Generac 15KW Natural Gas Problem.
Post by: Chuck in Indiana on December 07, 2021, 05:44:57 PM
Quote
sprayed an engine starter in both chambers and all I got was a back fire.
Hmmmm. I've never seen an engine with good ignition that wouldn't run when you did that, but you say you have good spark.. how about compression? Timing? Just throwing out ideas..
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 07, 2021, 06:30:09 PM
Hmmmm. I've never seen an engine with good ignition that wouldn't run when you did that, but you say you have good spark.. how about compression? Timing? Just throwing out ideas..

There is spark but not what I’d call a robust spark. According to the tech on Generac these engines require a Champion plug and the ones I replaced were a Autolite plug so I will pick up a pair tomorrow. Haven’t found a compression range for these engines; unfortunately these engines do not have a long lifespan according to the owner’s manual.
Title: Re: Generac 15KW Natural Gas Problem.
Post by: Kiwi_Roy on December 07, 2021, 11:30:58 PM
Do you have a link to a manual by any chance, particularly one with a schematic diagram?
Failing that a Model No and year of manufacture.
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 08, 2021, 10:49:16 AM
Do you have a link to a manual by any chance, particularly one with a schematic diagram?
Failing that a Model No and year of manufacture.

Roy, the ownership manual PDF should have the wiring diagram for a 15KW generator.
https://www.generac.com/service-support/product-support-lookup/product-manuals?modelNo=0046753

The Generac forum suggested that I get a manometer to check the volume of gas coming out of the regulator because when the suggested covering the intake while starting, which I had already tried, that indicated to them that there was no or little fuel getting to the engine. Anyway, ordered the tool and going to install the new plugs.   
Title: Re: Generac 15KW Natural Gas Problem.
Post by: PJPR01 on December 08, 2021, 04:26:08 PM
When was the last time it ran?  Does it automatically cycle every week on a test cycle?

We have a 22 kw Generac I put in after Hurricane Harvey in 2017...great peace of mind, and we've used it quite a bit.  Nice to be the only house with lights while it's total blackness all around.

You could call the tech from your local Generac service center, wouldn't cost much to have them come out and service it, check for faults if you come up empty after trying everything.
Title: Re: Generac 15KW Natural Gas Problem.
Post by: blackcat on December 09, 2021, 05:38:47 AM
When was the last time it ran?  Does it automatically cycle every week on a test cycle?

We have a 22 kw Generac I put in after Hurricane Harvey in 2017...great peace of mind, and we've used it quite a bit.  Nice to be the only house with lights while it's total blackness all around.

You could call the tech from your local Generac service center, wouldn't cost much to have them come out and service it, check for faults if you come up empty after trying everything.

I know it was working in September, as you know that is peak hurricane season so I’m guessing it last ran in October or November. And it’s set to cycle once a week.  I’m not going to call a tech until I’ve exhausted all my options.  The manometer should get here today or tomorrow and then I will know if the fuel regulator is working and if it isn’t then it’s just a question of getting the part and installing.  No faults on the deck. This unit is 16 years old and this is the first time it has been a problem.

Generator attempting to start:

https://youtu.be/tiG8tFokqEA