Martythed
I have a Generac model 5501 (8KW/LPG) with about 45 hours on it that seems to have developed an interesting symptom over the last several months.

After doing my weekly tests with around 3KW or so load, the engine will surge during the cool down period when there’s no load on it. By “surge” I mean that the engine speed varies at about 3 or 4 cycles per second. The engine does this only with no load (or a very light load…. 100/200 watts) but otherwise works fine with a decent load on it (1KW or so).

This unit, as you probably know, has a mechanical governor on it and I can see it moving in time with the engine surges.

I recently did my annual oil change and put in a new spark plug but this made no difference. I don’t know much about the mechanical side of the generator, but I wonder if something in the choke might be causing this phenomenon. Also, I haven’t checked the valve adjustment (it has less than 50 hours on it) but the unit starts right up and runs fine with a load.

Thanks for any ideas.

Marty
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d11gnccer
The adjustment screws that set the governor spring tension likes to move. I have even ran a few calls where the seconday adjustment screw fell apart. I like to drop a dab of blue loctite on the threads before adjusting the governor. Might be your problem?
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Martythed
Thanks, I'll be checking the governor scews tomorrow.

BTW........ I did the weekly test today and started the genset up in the manual mode and let it run for 10-15 minutes without any load and the engine speed stayed constant. I then shut it down and immediately started it up again, with no load, and sure enough, the engine started to surge. As soon as I put a load on it, the surging goes away. Marty
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78buckshot
Make sure the bellows between the air filter box and throttle is not cracked, also check the breather tube for cracks.
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Martythed
Thanks Buckshot, but I don't think my genset has a bellows on it. I've been reading about how they crack and I've looked for one but couldn't find it; I'll have to check again and see if its there.

Marty
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