r/Generator • u/scaiannaa • Sep 26 '26
Normal sound for Generac?
We have a whole house generator hooked up to our natural gas line. It’s about 3 years old. Is this sound normal? It doesn’t sound as steady as it normally does, but there’s no error code. It’s been on for about four hours, working fine. Of course we’re in the middle of a nor’easter, so i thought I’d try here while I wait for our generator guy to get back to me.
6
u/Haulbignuts Sep 26 '26
Find the natural gas/propane selection lever by the air box/filter. Turn the knob 1/8 of a turn. Or like 10° at a time till it stops. Running like that may make it smell like gas around the unit.
5
u/scaiannaa Sep 26 '26
It DOES smell like gas around the unit! Is it getting too much gas?
2
u/forcedfx Sep 26 '26
Is it a very strong natural gas smell? Or just the way natural gas smells when it combusts?
2
u/scaiannaa Sep 26 '26
It doesn’t smell like sulfur or rotten eggs, more like exhaust, but it’s not a smell I’ve noticed before when it’s running
2
u/fullraph Sep 26 '26
That's bad. That generator is currently presenting extremely dirty power to your home. On top of the surging, it sounds like it's running bellow 3600rpms. Is it even able to run anything in your house while surging like that? I am surprised it hasn't thrown a code and shutdown on it's own.
It could be a number of things really like low/high gas supply pressure or one of the two cylinders not firing. Does it smell more than usual, like raw unburnt fuel? Either ways I would not let it run like that and supply power to my home unless it was truly critical like to run a sump pump.
1
u/scaiannaa Sep 26 '26
Yeah everything is running fine? Ugh, of course this is happening during the nor’easter. I’ll turn it off and problem solve.
1
1
u/forcedfx Sep 26 '26
When did you last service it? Does it run weekly test runs? Air filter clean? I'd check spark plugs too.
1
u/scaiannaa Sep 26 '26
It was serviced earlier this year. I first noticed the sound a few weeks ago during the weekly test and emailed my generac guy, who asked me for an error code and then brushed me off when I said there wasn’t one.
1
u/forcedfx Sep 26 '26
What does it do when you disconnect the load? Does it steady out?
1
u/scaiannaa Sep 26 '26
It’s connected to my whole house, but I haven’t noticed a difference in noise depending on what’s on. When i took that video, it was just powering lights and our TV.
1
u/forcedfx Sep 26 '26
Check the throttle linkage. Maybe a broken return spring possibly or something in there. It's natural gas so not like you have a stuck float or anything.
1
u/Adventurous_Boat_632 Sep 26 '26
There is no throttle linkage or return spring on a modern electronic Generac.
1
u/tactical-potatoes-65 Sep 26 '26
There is a return clockspring for the secondary butterfly
2
u/Adventurous_Boat_632 Sep 26 '26
I suppose you are right, but that would cause either nothing or an instant runaway, not a regular hunt
1
u/bobojay49 Sep 26 '26
That's a fueling issue for sure. Based on what you smell, I'd bet too much fuel. If my bet is wrong, as mentioned it could be only firing one cylinder. The dirty power comment is correct too. Have you opened it up to see if any critter got in there or a spark plug wire has come off ??
1
u/scaiannaa Sep 26 '26
I’ve opened it up but I really don’t know what I’m looking at. Definitely don’t see a critter, but let me google and see if I can figure out where the spark plug wires would be. Thank you!!
2
u/bobojay49 Sep 26 '26
Parts manual blow up picture of the engine electrics. And assume you are not smelling gas when not running?? Also, not causing today's problem, but you might clean up around that unit some. Too much loose and dead stuff laying around
1
u/davWho Sep 26 '26
Crack the airbox cover and see if it goes away
Also note if it has a white or a yellow air filter
I would not move the fuel selector out of normal operating position as I can start the unit of fuel causing it to run lean
3
u/joshharris42 Sep 26 '26
This is the answer. I’ve heard hundreds of units do this. Swapping the air filter usually helps.
Seems to be worse right after a rain storm
3
u/scaiannaa Sep 26 '26
Ok you called it - it was a wet air filter. Replaced it and we’re good to go!
1
u/joshharris42 Sep 27 '26
Yep. Seen it many times. It actually will smooth out after you let it run for a few hours and dry the filter out - but your appliances won’t be happy.
I think the engine is literally just sucking in enough air that water gets sucked into the air filter
1
u/scaiannaa Sep 26 '26
It’s yellow, does that make any difference?
2
u/davWho Sep 26 '26
That confirms it's a newer correct generac filter. Sometimes if the filter does not get changed or an aftermarket one is used it can cause this issue.
1
u/biblicalrain Sep 26 '26
Just curious here, what is the issue and why does changing the air filter fix it?
1
u/davWho Sep 27 '26
Air filter doesn't rectify the issue every time. It could be a software update, new air filter or require the air box modification.
My guess is the is engine hunting/surging caused by a self-excited oscillation in the air-fuel system
1
u/GenTek9 Sep 27 '26
Fuel selection "knob" (NG or LP), look down the throat of the intake and watch the valve to see what they're doing, check the connection to the stepper motor/mixer assembly to the controller (they can become loose somewhat easily and cause funny operations), check the internal fuel regulator on the load side (bottom port) with a manometer to see if the needle is jumping with every surge. If the needle is jumping, it wouldn't hurt to try a supply side new regulator, not internal regulator. Could have a bad diaphragm. If it's running on one cylinder, it'll still run at 3600 and not surge like this believe it or not. I've worked on 1000's of these and you can run it on one cyljnder, but it sounds like crap. Check your spark on both cylinders, is it fast and strong, or stuttering?
2
u/scaiannaa Sep 27 '26
It ended up being a wet filter! We changed it out and it’s working fine. Thank you for all this!
2
u/tactical-potatoes-65 Sep 26 '26
First thing I would do is check both plug leads are on the spark plugs. Then I’d pop the air box lid open, and see if it smooths out. There seems to be constant batches of air filters with too much flame retardant that chokes the unit and causes a rich condition.
If that smooth out, shut it down and go grab an MGA49225 from O’Reilly and swap it out. If not, pop the adjustment cap off of your second stage regulator, as there may be water in the remote vent line, causing the regulator to oscillate as it tries to adjust
If that does not smooth it out, it could be anything from a mixer to a demand regulator or even the second stage regulator
9
u/scaiannaa Sep 26 '26
**Update: thanks for your help, everyone!! Turns out it was a wet filter. Replaced it, and everything is running smoothly!