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Generac GP6500 generator surging "hunting" while idle.


twood020's Avatar
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11-11-14, 11:49 AM   #1  
Generac GP6500 generator surging "hunting" while idle.

I have a Generac GP6500 generator that's surging while idle. It has 4.5 hours on it. I've run it for 10 minutes every month. This started last month, I just tried draining all fuel, removed the air filter cover and filter, sprayed carb cleaner in the carb and filled with fresh gas/sta-bil. It's essentially brand new, never even actually used during a power outage, just maintenance runs. I took a short 1 minute video of what it sounds like (below):

https://www.youtube.com/watch?v=zzZJ...ature=youtu.be

Any thoughts would be much appreciated. Thank you.

 
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11-11-14, 01:41 PM   #2  
Drain the fuel and mix about 2oz of SeaFoam in a pint of gas startit and let it run for about 10 minutes, shut it off and let it set for 20 minutes then start it and let it run dry, the SeaFoam may dissolve the buildup of varnish. Have a good one. Geo

 
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11-11-14, 03:07 PM   #3  
If that does not do it you'll have to remove the carburetor, disassemble and give it a cleaning. Fuel still goes bad even if the engine is run regularly so while regular running helps it's not 100% effective if you're only doing it a short while so that you never burn through a tank of gas and need fresh fuel.

Engines that get little use I fill with the minimum amount of fuel. If it runs dry during a monthly test run it's no big deal and you can throw in a splash more. Keeping a minimum of fuel in the tank helps insure that you're rotating it out and getting fresh fuel into the tank more freqeuently. It also wouldn't hurt if you ran the engine longer each month. Get some quarts work lights, shop vac or anything else that pulls a decent load and plug into the generator and let it run with a load to help insure the engine gets up to full temperature. Even though the engine is turning at high working rpm's during your test runs without a load you're burning minimal fuel and the engine stays cooler. You want it to get hot and stay hot for 10-15 minutes to cook off any moisture or fuel that may have gotten into the oil.

 
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11-14-14, 12:32 PM   #4  
Thanks for the feedback guys, I'll try it out this weekend. Hopefully the SeaFoam works, never disassembled a carb before. Much appreciated.

 
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11-16-14, 05:30 PM   #5  
Seafoam did the trick!! Did it exactly as described, after initial 10 minute run it had already cleared up. Amazing stuff, thanks again for the quick responses.

 
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11-17-14, 09:34 AM   #6  
Success is a wonderful sound. Have a good one. Geo

 
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11-17-14, 12:34 PM   #7  
After running it shut the fuel valve off and let it run out of fuel instead of shutting it off.
Only use nonethanol fuel!
Any power tool shop or marina can tell you where it's sold.
I know in my area there's at least 6 places that sell it within 10 miles, so it's out there.

 
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11-17-14, 06:39 PM   #8  
I agree on using premium grade fuel.
Methanol seems to make fuel go bad very quickly.
I also agree that you should run the generator longer, at least a half hour and at least 50% loaded.


GregH.........HVAC/R Tech

 
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