Hunting Generator

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johns10

Member
Joined
Dec 9, 2006
Posts
16
Location
nevada
I have an Onan MicroQuiet 4000 Generator. Has anyone had an issue with this generator or any other type that keeps hunting for the proper output level when the load is varied?
 

Shayne

Well-known member
Joined
Jan 22, 2006
Posts
4,324
We have had Onans on the last 5 MHs and yes their have been times when they didn't seem to want to settle down and run evenly.  Doubt if it was anything we did to cause it.   I always figured it more or less a combination of the quality of gas and the load.  Also,  once I changed the inline gas filter, another thing I had fuel line problems.  Spent a small fortune trying to cure that one, even changing the fuel pump and having the full 75 gal tank drained and flushed.  It was a collapsed fuel line about a foot from the tank.  Changed plugs in the Onan once. Outside of that, sorry can't help
 

johns10

Member
Joined
Dec 9, 2006
Posts
16
Location
nevada
Thanks for your input. Have not replaced fuel filter, but I only have about 400 hrs. on it. I always use fuel stabilizer in my gas, so figured it wasn't a fuel problem. That might be the place to start though since the fella at Onan said it could be a number of things that could amount to over $2000 after they get through tearing into it. Not real helpful at Onan for advice. I do know they need to be exercised about once a month for a couple of hours at approximately half load to maintain efficiency. Better at that rate than no load for four hours. Good luck with yours in the future.
 

Jeff

Site Team
Joined
Apr 8, 2005
Posts
8,965
Location
SD/AZ
A surging Onan may very well be a fuel problem. If one of the two carb adjustment knobs won't solve the problem you may have varnish plugging up the carb or fuel lines from sitting which is why they want them run every month. I fixed ours by spraying carb cleaner into the carb several times.
 

3labs

Well-known member
Joined
Nov 18, 2006
Posts
57
Location
New Hampshire
Jeff Cousins said:
A surging Onan may very well be a fuel problem. If one of the two carb adjustment knobs won't solve the problem you may have varnish plugging up the carb or fuel lines from sitting which is why they want them run every month. I fixed ours by spraying carb cleaner into the carb several times.

Jeff is on the money with the fuel problem. I would check the carb it needs to be disassembled and the float checked. I have worked on several Onan generators and they had a problem with the float filling with fuel. And one of the symptoms was surging. They used a metal float and then changed to a plastic float this stopped the problem. And if the float is OK it will give you a chance to give the carb a good cleaning, Good luck

Brian
 

Shayne

Well-known member
Joined
Jan 22, 2006
Posts
4,324
I'm an oldtime auto fool and believe in the old gas treatment additives.  I generally add a small bottle of the cheaper additives to my fuel tank for each 25 gals of fuel in the tank each 5th or 6th time I fuel up.  Since I've been doing this on the MH, I ;'ve had no problems  since my huge bill to drop the tanks.  I works for me.  Others may disagree and that's therir choice. Also will storage I do add Sta-Bol (Sp) 
 

fredethomas

Moderator Emeritus
Joined
Mar 2, 2005
Posts
420
Location
SIERRA VISTA, AZ or on the road.
There is a remote chance that the oil is getting low??  They shut off with low oil.  Try running without the air filter and see if it smooths out.  A rich or lean mixture will cause the governor to hunt.
 

172ndLIB

Active member
Joined
Dec 11, 2006
Posts
39
Usually surging of the genset is caused by one of two things.  Either carberator adjustment or tune-up.  Very seldom is it anything else but if you have the summer/winter handle on the aircleaner housing make sure it is in the proper position.
 
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