Generac 14kw troubleshooting high rpm shut down

bgelectric

Senior Member
Im trying to figure out why this 14kw generac shuts down right away after start up...
It hits a high rpm then shuts down right away.
When you hold your hand over throttle intake it runs fine as if your choking it...
 

GoldDigger

Moderator
Staff member
Im trying to figure out why this 14kw generac shuts down right away after start up...
It hits a high rpm then shuts down right away.
When you hold your hand over throttle intake it runs fine as if your choking it...
If it hits high RPM but not overspeed, and then shuts down, does it have a Ground Fault Detector that kills the engine as well as opening the output circuit?
If it actually overspeeds, I would say that the governor is defective or disconnected, and the fail safe overspeed control is killing it.
 

FJSFRED

Member
Location
Chino, CA
fjsfred

fjsfred

Check the governor. There is a rod going to the throtle control which could bs as simple as a blade in the cooling fan area of a motor operated bell-crank that is connected to the same rod witch controls the speed of the engine. They usually have a spring to give it tenion. I could be that this spring as come off or just broke. That is the basics without knowing what type of gererator you have and the age. If you need the manual google the make and model number and it may come up. Hope this helps.
 

GoldDigger

Moderator
Staff member
Check the governor. There is a rod going to the throtle control which could bs as simple as a blade in the cooling fan area of a motor operated bell-crank that is connected to the same rod witch controls the speed of the engine. They usually have a spring to give it tenion. I could be that this spring as come off or just broke. That is the basics without knowing what type of gererator you have and the age. If you need the manual google the make and model number and it may come up. Hope this helps.
If the spring comes off an air-vane type governor, it usually will allow the governor to close the throttle at a lower rpm that it should, but other mechanisms can work differently.
A mechanical jamming of the governor linkage (accumulation of crud or bent wires for example) can cause overspeed because the governor cannot close the throttle.
Basically find out where the throttle linkage is located and make sure that it moves freely. Then follow it till you find out what is supposed to be moving it.
Or look at the parts diagram. :)
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
Im trying to figure out why this 14kw generac shuts down right away after start up...
It hits a high rpm then shuts down right away.
When you hold your hand over throttle intake it runs fine as if your choking it...
Is it supplying a UPS? They don't like each other if the UPS doesn't have a load.
Is the Govenor electronic? It is adjustable by a pot.
Is this a new generator just started? or a problem on a generator that had been running fine and now this has started?
 

hurk27

Senior Member
Im trying to figure out why this 14kw Generac shuts down right away after start up...
It hits a high rpm then shuts down right away.
When you hold your hand over throttle intake it runs fine as if your choking it...
Generac's have an electronic throttle, no vanes springs or anything like that.

If it is trying to reach full speed (3600 RMP's) it can sound like it is over speeding when its not, the couple of times I was called out on this was a homeowner installed unit and they undersized the gas line, they tried to run 1/2" IPT instead of the 3/4" or 1" that these units need, also if this was a already installed unit and ran fine before then you could have a bad gas regulator or the service gas supply is too small, the electronic throttle is controlled by the computer via the frequency output of the alternator, as load tries to slow the generator down the computer opens the throttle as needed, it is possible that the computer can no longer reference the alternators output and shuts down on error, this can also result in over speed shut down.

As to the other responses most generators have not had a vane governors for years if ever because they have to have an electrical way to maintain the RPM's which maintains the frequency at 60hz, and any load will try to slow the engine down which will drop the frequency, older units and many portable ones used a solenoid that the controls gave it a varying current to control the throttle, but most of todays stationary back up generators use electronic stepping motors to control the throttle just like the newer cars as they can do it with much more precision, Generac's on board computer will report most faults, but the low gas supply is one it doesn't report on in my experience, the newer Nexus computer might but I don't know.

Most of Generac's manuals are available on line for their home units, but you have to have the model and serial numbers to get the correct ones, check here
 
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GoldDigger

Moderator
Staff member
If it is trying to reach full speed (3600 RMP's) it can sound like it is over speeding when its not, the couple of times I was called out on this was a homeowner installed unit and they undersized the gas line, they tried to run 1/2" IPT instead of the 3/4" or 1" that these units need, also if this was a already installed unit and ran fine before then you could have a bad gas regulator or the service gas supply is too small, ....[/URL]
Are you figuring from the 14kW that it must be an NG or LPG unit, or are you just guessing?
Putting a restriction on the air intake could be causing increased manifold vacuum and drawing more gas through an undersized supply line.
Whereas on a gasoline or diesel unit it might just be preventing overspeed by messing up the fuel/air mixture. (A diesel would not have a throttle plate in the first place, right?)
 

RLyons

Senior Member
Is this a new unit, old unit? Does it do it all the time? If it runs with your hand over it sounds like a major intake leak or more likely a stuck butterfly or faulty stepper.
 

templdl

Senior Member
Location
Wisconsin
Im trying to figure out why this 14kw generac shuts down right away after start up...
It hits a high rpm then shuts down right away.
When you hold your hand over throttle intake it runs fine as if your choking it...
Have you asked Generic? I would like to think that asking the manufacturer would be the first place to ask.
 

hurk27

Senior Member
Are you figuring from the 14kW that it must be an NG or LPG unit, or are you just guessing?
Putting a restriction on the air intake could be causing increased manifold vacuum and drawing more gas through an undersized supply line.
Whereas on a gasoline or diesel unit it might just be preventing over speed by messing up the fuel/air mixture. (A diesel would not have a throttle plate in the first place, right?)
Nope no guessing, Generac doesn't make a 14kw portable which is the only series that they have that uses gasoline, the only 14kw is the Guardian series which is NG/propane.

And the symptoms the OP described if the generator is not shutting down on over speed is exactly as I found when the generator is starving for fuel (NG)

As far as diesel goes, they only offer a diesel in their industral series and they only make a 10kw then jump to a 15kw, up to a 600kw they don't offer a 14kw diesel.

The 14kw is a newer series they came out with when they came out with the Nexus computer controller system, prior to this it was a 15kw that on NG was derated to 14kw

over the years I have installed and repaired hundreds of Generac's but when they got greedy and changed the ability to order parts and closed their tech support to only their contractors who spent all the money to go through their training seminar and purchase $$$ in stock of parts they require that you may never use, I quit pushing them, Ive had a few of my customers get ripped off by their so called trained tech's and I wasn't very happy, had one try to tell my customer I was over loading their generator because the breaker handles added up to more then the generator could handle, after some nasty calls to Generac they finely called my customer and apologized and admitted their tech was wrong, but still since I can not get repair parts from then or use their tech support (which I very rarely needed) I just tell my customers that I will install them but I can't offer any support for them.

The problem as described by the OP is kind of vague as he didn't really say it was posting a overspeed error every time it shut down, but he did say it has given that error which led me to believe it wasn't the problem at this time, I have had a few customers think they were running way to high of an RPM because at 3600 rmps they do sound like they are screaming, so I did guess that maybe this is what the OP was thinking, as a unit with undersized NG lines or a undersized NG regulator can react just like this, it will start try to go to full speed then die, push the choke on or hold your hand over the throttle body opening and it will try to run but not at the 3600 rpms it needs to, what happens is the NG regulator fills the lines up until it get to the .5psi or 5 inch pounds of pressure, but when the generator bleeds off the pressure when starting is drains the line and the regulator wont allow enough fuel to keep the line at the required .5 psi required by the generator which wont open the solenoid gas valve, putting your hand across the throttle intake allows the vacuum to pull the solenoid open so it allows it to run but at a reduced RPM level and if you tried to load it it would just die, had one that the house didn't have a large enough gas service to feed both the generator and furnace, the generator would start and run just fine until the furnace kicked on and the generator would just die, the gas company changed their regulator and it worked just fine, this is why it is very important to follow the instructions in the manual on sizing the gas line and gas service.

If it is showing the over speed fault on the computer every time is shuts down then there are other problems such as the computer has lost RPM communication with the from the speed sensor, I had this once that was caused by field mice that got into the generator and chewed up some wires, I repaired the damaged wires and put moth balls in it and never had another problem as moth balls drive away most critters like that.

But again arm chair trouble shooting is not the best way to find a problem and it could very easily be something else, so who knows.
 
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qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
Have you asked Generic? I would like to think that asking the manufacturer would be the first place to ask.
From what has been said here about Generac's customer service they will not talk to you unless you are a dealer.
 

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
From what has been said here about Generac's customer service they will not talk to you unless you are a dealer.
hurk27 said:
over the years I have installed and repaired hundreds of Generac's but when they got greedy and changed the ability to order parts and closed their tech support to only their contractors who spent all the money to go through their training seminar and purchase $$$ in stock of parts they require that you may never use, I quit pushing them, Ive had a few of my customers get ripped off by their so called trained tech's and I wasn't very happy, had one try to tell my customer I was over loading their generator because the breaker handles added up to more then the generator could handle, after some nasty calls to Generac they finely called my customer and apologized and admitted their tech was wrong, but still since I can not get repair parts from then or use their tech support (which I very rarely needed) I just tell my customers that I will install them but I can't offer any support for them.
That's the long and short of it in a nut shell in BOLD print. They circle the wagons and protect their own. Try this company : http://www.apelectric.com/Generac-Guardian-Transfer-Switches-RTS-s/36.htm . Some of my colleagues have purchased parts from them with no hassle but you have to know what parts to order. BTW, you will not be able to do any warranty work unless you're a dealer. If it's a warranty issue you'll have to pay the $175.00/hr vig to have an "authorized" representative do the work.
 

templdl

Senior Member
Location
Wisconsin
From what has been said here about Generac's customer service they will not talk to you unless you are a dealer.
So, from what you are saying the OP has in fact tried to talk to Generic already and was basically blown off by them. This is a bit interesting since they are growing and have just completed a major renovation, and I do mean major, of their main factory converting a large portion of their manufacturing floor to more office space. I wasn't aware that they aren't supporting customers with a help line.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
So, from what you are saying the OP has in fact tried to talk to Generic already and was basically blown off by them. This is a bit interesting since they are growing and have just completed a major renovation, and I do mean major, of their main factory converting a large portion of their manufacturing floor to more office space. I wasn't aware that they aren't supporting customers with a help line.
I didn't mean to imply OP had talked to Generac. That wasn't said.
What I meant was from what has been said on this forum about Generac they will not talk to you unless you are a dealer.
 

Daja7

Senior Member
Sounds like a stepper motor. You can manually move the stepper motor linkage back to reduce or increase rpm. If that rhelps the issue then it is a stepper motor that needs to be replaced.
 

grich

Senior Member
Probably doesn't apply to the OP, but I'll toss in my weird Generac experience. Client has an 80KW set at a radio tower site, which was shutting down right after starting, either on low oil pressure or overspeed, depending on which alarm triggered first. Prior to this, the starting battery had exploded and they replaced it. The genset control box memory had cleared, so all of the alarm and engine parameters were wrong (including stuff like the number of teeth on the flywheel, etc.) The genset installer had left behind two copies of the setup sheet, so I was able to reprogram it and make it run again.
 

templdl

Senior Member
Location
Wisconsin
I didn't mean to imply OP had talked to Generac. That wasn't said.
What I meant was from what has been said on this forum about Generac they will not talk to you unless you are a dealer.
Thanks. That being said the it may be benefit the OP to actually call Generic. If Generac does respond to his question and provides him with an answer to his issue then it would spare the OP with all of the guessing from those who have responded to his OP.
If he gets blown off by Generic it will only verify what the general opinion of what Generac's policies are.
This is what the Generac site says. Let's see if the OP actually calls Generac or not. If they defer him to a "certified dealer" or answer his question directly will clarify the general opinion of the Mike Holt forum members.

GENERAC HAS YOU COVERED
From our trusted network of certified dealers to our knowledgeable on-site staff, Generac is commited to providing our customers with unsurpassed product and support. Below are some convenient tools including technical specifications, product registration and customer service information that will ensure you are never left in the dark.

CONTACT GENERAC
24/7 365 Customer Care
Call: 1-888-GENERAC
******* (1-888-436-3722)
SERVICE
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
Thanks. That being said the it may be benefit the OP to actually call Generic. If Generac does respond to his question and provides him with an answer to his issue then it would spare the OP with all of the guessing from those who have responded to his OP.
If he gets blown off by Generic it will only verify what the general opinion of what Generac's policies are.
This is what the Generac site says. Let's see if the OP actually calls Generac or not. If they defer him to a "certified dealer" or answer his question directly will clarify the general opinion of the Mike Holt forum members.

GENERAC HAS YOU COVERED
From our trusted network of certified dealers to our knowledgeable on-site staff, Generac is commited to providing our customers with unsurpassed product and support. Below are some convenient tools including technical specifications, product registration and customer service information that will ensure you are never left in the dark.

CONTACT GENERAC
24/7 365 Customer Care
Call: 1-888-GENERAC
******* (1-888-436-3722)
SERVICE
Interesting... Is this smoke and mirrors or has Generac changed their policy on customer service?
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
Interesting... Is this smoke and mirrors or has Generac changed their policy on customer service?
Out of curiosity I visited Generac's face book page.
Read some of the comments and 80% of them were not favorable......
Hmmmmmm
 
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