Generator won't idle

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cbarr

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I was testing a Generac generator and after starting it and before any load was put on it it would surge. RPMs would increase and decrease every few seconds but would not level out to a normal idle, I ran it for 15 minutes, still the same results. I was afraid to put a load on it because the power output would not be consistent. I did not know what to recommend to my client. What would cause the the generator to act like that. Gas was clean, filters were new, oil had been changed within the last few weeks before I started it. The system has a self start timer and it starts once a week and runs for a short period of time then shuts off. The house is vacant so no one can tell me how long it has been running this way.:-?
 
catchtwentytwo

catchtwentytwo

Senior Member
cbarr said:
I was testing a Generac generator and after starting it and before any load was put on it it would surge. RPMs would increase and decrease every few seconds but would not level out to a normal idle, I ran it for 15 minutes, still the same results. I was afraid to put a load on it because the power output would not be consistent. I did not know what to recommend to my client. What would cause the the generator to act like that. Gas was clean, filters were new, oil had been changed within the last few weeks before I started it. The system has a self start timer and it starts once a week and runs for a short period of time then shuts off. The house is vacant so no one can tell me how long it has been running this way.:-?
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Do you have an idea how long the unit has been in service? Easy for someone to put fresh gas in the tank but if it had been sitting around for too long, could be the carburetor is "gummed up".
 
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poeboy

Member
Location
Los Angeles Metro area
Lotsa stuff to look at as others have said..... could also be air getting into the fuel system via a loose filter connection.

You said it was gas, is it a spin on or a drop in filter with a lid that seals?? Maybe even a small crack in the supply hose near an inline filter.....

Is it a small (1 or 2 cylinder) ICE that a small engine guy can look at for a small expense?? I'd suggest a can of drygas, or something similar, run an entire tank full through it, then add fresh fuel again. If the same problem is happening, then go through other troubleshooting steps.

It wouldn't hurt to get a copy of the manual from the manufacturer and see if they address that particular problem in their manual as well.
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Minimum Load?

Minimum Load?

Is it possible that the generator is looking for a minimum load? Perhaps the speed regulation won't function properly unless the generator is loaded to some extent.
 
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hillbilly1

Senior Member
Location
North Georgia mountains
Occupation
Owner/electrical contractor
cbarr said:
I was testing a Generac generator and after starting it and before any load was put on it it would surge. RPMs would increase and decrease every few seconds but would not level out to a normal idle, I ran it for 15 minutes, still the same results. I was afraid to put a load on it because the power output would not be consistent. I did not know what to recommend to my client. What would cause the the generator to act like that. Gas was clean, filters were new, oil had been changed within the last few weeks before I started it. The system has a self start timer and it starts once a week and runs for a short period of time then shuts off. The house is vacant so no one can tell me how long it has been running this way.:-?
Click to expand...

The gas may have been clean, but that don't mean it was not stale. That is a big problem with gas and diesel generators, the shelf life of fuel is limited. Propane or Natural gas is a better choice. I have also heard that the ethanol blended gas draws moisture and deteriorates seals.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
gadfly56 said:
Is it possible that the generator is looking for a minimum load? Perhaps the speed regulation won't function properly unless the generator is loaded to some extent.
Click to expand...
This response gets my vote. I've had a new smaller Generac (7kw) 'hunt' unless loaded. Generac had no solution.

I'd still contact then, though. This was a couple of years ago, and they may have new info on solving the issue.
 
gadfly56

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
LarryFine said:
This response gets my vote. I've had a new smaller Generac (7kw) 'hunt' unless loaded. Generac had no solution.

I'd still contact then, though. This was a couple of years ago, and they may have new info on solving the issue.
Click to expand...

Carry a 1500w hair dryer with you. If it has a "low" setting, you can use it to test rate-of-rise heat detectors.
 
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