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Topic: Cummins Onan MicroQuiet 4kw generator (Read 211 times) previous topic - next topic
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Cummins Onan MicroQuiet 4kw generator
I replaced the carburetor on the LD generator today.  No matter what I did as far as exercising, it kept getting harder and harder to start and finally, I was able to stop it by loading it with a shop vac.

The rig is a 2007 IB30.  When we bought it in 2013 from its original owner, it had 15,011 miles on the odometer and 65 hours on the generator.  If you do the math, the first part of the generator's life did not see much exercise.  The generator has 135 hours on the Hobbs meter now, so I have not been very good about exercise, either.

So - the carburetor was gummed up with varnish.  The generator started almost instantly after prime with the new carburetor installed.

Here is what I've learned from the generator professional who performed the work:

1.  Always use a good cleaner additive in your gas.  Chevron Techron or Seafoam was suggested.

2.  Always treat your gas with Sta-bil if you will be storing the rig for any length of time.  Add the Sta-bil at a time when it will circulate well in the main tank then run the generator.

3.  If you use your generator and you won't be using it again within the next day or two, drain the carburetor bowl.  How about that? I didn't even know you could do that.  If you look at the carburetor, you will see the only stainless steel Phillips head screw on the carburetor.  Right beneath it you will notice a formed drain pan that will hold any fuel that drains from the open carburetor bowl.  Place a shop towel or several folded paper towels in the drain pan and open the carburetor bowl drain screw.  After the fuel has drained, tighten the drain screw.  The professional said this will go a long way toward keeping the carburetor free of gum and varnish.

4.  Priming.  When you prime your generator before starting, don't be afraid to hold the prime switch for 15 or more seconds.  It will ensure a good prime and you cannot over-prime the carburetor because the bowl float will shut of the fuel line from the priming pump.

5.  Priming - part 2.  Prime your carburetor even if you have just run it a short time before and want to restart it.  The heat-soaked carburetor bowl will evaporate fuel, so go ahead and prime a hot generator.

6.  Let it breath.  The generator professional that did my repair pointed to the locking door over the generator compartment and said that a solid door without a breathing vent is a poor design.  He told me that the generator door should be latched open to permit the generator to intake cooling air without restriction.  He also told me that running the generator while moving without the door open is ok because there is sufficient air flow around the generator compartment from the motion of the rig.

If you are in Arizona and have a generator problem, I recommend AZ Generator (Chuck).  When I first called him, he talked with me at length and gave me some things to try with the generator to see if I could avoid using his services.  He actually said he would rather help me over the phone than have to charge me for parts and service.  When the steps he told me to take did not work, I was happy to have him do the necessary work.    AZ Generator | Home Page

Dan and Lynn
2007 IB-30

2007 IB-30
Re: Cummins Onan MicroQuiet 4kw generator
Reply #1 –
Dan and Lynn,
Thanks for the info and the referral.  And one local to us. :D
Jane
Jane & Scott
Currently have a 1989 TK  LD we did a lot of upgrades on.
Bigfoot 25RQ Twin on order with early summer 2024 ETA

Our smartphone autocorrects into very poor English.
 We disclaim the illusion of ignorance this creates as we have enough ignorance we rightly claim.
Re: Cummins Onan MicroQuiet 4kw generator
Reply #2 –
Quote from: dsandsaz  - 

3.  If you use your generator and you won't be using it again within the next day or two, drain the carburetor bowl.  How about that? I didn't even know you could do that.

5.  Priming - part 2.  Prime your carburetor even if you have just run it a short time before and want to restart it.  The heat-soaked carburetor bowl will evaporate fuel, so go ahead and prime a hot generator.

I've never primed my generators, and they've always started immediately if they've been used in the last week or so; in 8-10 seconds otherwise. The "priming", according to my Onan manual, is not what is normally called priming (a small squirt of fuel into the intake manifold); instead, it means running the fuel pump to fill the carburetor bowl. I'll try that next time it's been a month since I've used the generator, and maybe it won't take that 8-10 seconds to start.

I don't think a heat-soaked carburetor bowl will evaporate fuel - like I said, my generators start easily, no priming, if they've been run in the last week, so it doesn't appear significant amounts of gas evaporate from hot generators. I don't think there is any harm to it, though.

I can see no advantage to draining the carburetor bowl unless you will let it sit for more than a month or two. I believe that's Onan's recommendation, too. Carbs are made to hold gasoline, and it won't go bad in a two days. I run my generator for 30 minutes every month, which brings in more gasoline so the bowl doesn't dry out.
2005 Jayco 24SS