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Onan MicroQuiet 4000 KY - Flooding


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  #21  
Old 04-05-2014, 03:31:27 PM
PnishrPW PnishrPW is offline
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

Is the solenoid on the bottom of the carb fuel cut or idle mixture?? If idle mix, may have an issue in engine electronics keeping it constantly on, just a WAG.
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  #22  
Old 04-05-2014, 03:41:08 PM
Kpack
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

Only other thing is the fuel pump. Maybe the experts can tell you if someone installed one that is to strong maybe its pushing by.
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  #23  
Old 04-05-2014, 04:01:44 PM
len k len k is offline
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

Got to read manual,I'm not too familar with this model. But I think it's a fuel cutoff solindoid, so cylinder walls don't get oil washed off with gas when gen shuts off. gov should open throttle wide open when engine shuts off( goes to low rpm) and spark is off.
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  #24  
Old 04-05-2014, 04:24:22 PM
PnishrPW PnishrPW is offline
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

Quote:
Originally Posted by Kpack View Post
Only other thing is the fuel pump. Maybe the experts can tell you if someone installed one that is to strong maybe its pushing by.
If I read correctly, OP has tested w/ gravity feed.
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  #25  
Old 04-05-2014, 10:00:16 PM
Kpack
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

Hmm could the valves be that out of whack to pull to much fuel. But it sure sounds like the float.
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  #26  
Old 04-05-2014, 11:35:34 PM
len k len k is offline
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

Because solinoid is located at bottom of bowl, it likely shuts off flow of gas just before intake to adjustment screws. But since your problem is excess fuel not lack of it I suspect it's not your problem. I have not taken one appart to see how it's designed, but for engineering reasons I suspect it is separate from mix adjustment valves and not influenced by them.
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  #27  
Old 04-06-2014, 01:04:24 AM
On the road On the road is offline
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

Ok, here is where we stand now!

len k ----I did pull the vent hose, although this is unlikely the issue. The engine was sitting cold and the float is installed upside-down. The Gen started and ran. No issues. After a few minutes warming, I walked around into the RV and cranked on the Roof AC to full on coldest. A minute or so after that the AC was blow'n cold. Few more minutes and all was running very smooth. I turned the ac unit off and went around and shut down the Generator and replaced the oil (it was laced with gas from previous serious flood episodes). Now I was ready to let it run an unlimited amount. It proceeded to do the usual. I could get it started and running by cutting off fuel pinching the gas line, it would run rich for a little exhaling smoke and then clear up and purr up to speed. Sooner or later I'd blow the gas amount and it will either die off with too little fuel or cough a bit and I'd get it squared away again for another short stint or running.

len k - - - I don't think the vent hose played a role in the events that took place, I've had it run for a minute or two just as beautiful. I was going to put the hose back on to test the hose hypothesis after restarting the genset. No dice, yet. Can't get another smooth prolonged run out of her.

I pulled the carb again and super cleaned all; special attention given to the fuel intake. Put the carb float back in right side up. Put on another new fuel filter just before the carb fuel inlet.

No Go. Basic bad flooding and lots of choking off fuel to get it to fire.

I pulled the carb again. Flipped the float and put in the JB welded stiff float to see if this would cut off fuel more cleanly. No real change that was benefiting the situation.

Pulled the carb. Put in stock float needle and float upside down. All back on and starts, but does not run well for long and then begins coughing. Will not purr for long and needs to be hand fed.

I am at wits end. Will have to take some time off this and read the manual. Never have I had such a wild situation . . . .

It will run.
It will run perfectly and even with a load as it did today
, but .
What could convince me that the float situation is at fault, but actually be something quite different. I did not even use my gravity feed fuel system this morning when it ran so well. I hooked it right up to the stock gen fuel pump. I know the pump is not the issue, because the majority of the work I've done trying to solve this issue has been with my simple gravity feed fuel system with almost no pressure (funnel is less than a foot above the float bowl. I can even use the funnel to control the fuel input and keep the generator running a little better, but it almost always finds a reason to die off within a minute or less.

Gotta quit fer a bit.

Thanks again for bits of advice.

Kpack - - - you just might have something with the valve issue.

If too tight, might get some wild results when trying to run. Intake would do some really strange sometimes close completely and other times not quite. Maybe morph into something like what I'm experiencing. The exhaust . . . we'll I'm not sure what a very tight exhaust valve would create. Maybe this could working very well once in a while, yet often just loading up unable to breath property.

I'll check them, but I'm doubting this being the issue. I can get this thing to run smoothly by playing "fuel dispenser" (cutting off fuel and then letting some through at just the right interval). If the valves were tight, or one was, I'd not be able to get the generator through a flooding episode of coughing and smoking to a quick and smooth purr. The valves would likely be very consistent about bad operations once they'd warmed to the combustion gasses.

BUT all worth a closer look. . .

Next on the list - - - valve situation and inspection.
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  #28  
Old 04-06-2014, 10:36:08 AM
Kpack
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

This maybe in the thread but I didn't see it. With the carb off take the pin out of the fuel cut solenoid and put the cut off back on and then hook carb up to gravity feed and just hold the carb and see if the gas comes out or does the float hold or hot wire your fuel pump to see if it pushes past the float.

I believe there's a spring in that cutoff watch out for it.
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  #29  
Old 04-06-2014, 11:24:24 AM
len k len k is offline
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

Test carb alone to try to isolate problem...... I'ld do test Kpack said. But hook up a hose from carb to your Onan gas PUMP, hot wire pump. But I wouldn't take carb apart instead activate solinoid with a batery leads. With carb disconnected from engine and held LEVEL, see if gas leaks out. If it does you definately know carb is bad. But first with carb on engine check that controler sends solinoid 12V, not some lower voltage so you don't risk burning out solinoid during this test.

Onan pump (it's ~3psi) will give more pressure making it easier to see a leak. 3psi = tank held ~10 feet above carb. Using power to solinoid reduces any changes to carb over the way you are using it on engine ( you might accidental fix something by bypassing it and test will not represent the way you are using it on engine)


For your previous testing I think your gas tank/funnel 1 ft above carb is fine. The carb float and needle valve size on my older 7NHM Onan looks just like those of lawn mowers and snow blowers and their tanks have even less heigth above carb.

Carb test...... got an old lawnmower or snow blower engine that runs?? Could try putting Onan carb on it and see if it still acts up. That would confirm if it's a bad carb. Can use hose, clamps and spare flanges to temporarily make the carb to intake manifold connection, just has to be airtight. Or cast your own adapter from car -bondo, bondo is easy to drill and fabricate with. It's "plastic" don't make bolts too tight.


This idea works in reverse too. Take a carb and put it on Onan, but I would disconnect the AC voltage reg to protect it. They get stressed if they run at low rpm. Gov linkage likely won't line up so you might have to hold throttle for testing.

Last edited by len k; 04-06-2014 at 12:47:37 PM.
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  #30  
Old 04-06-2014, 12:00:37 PM
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EricWood EricWood is offline
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Default Re: Onan MicroQuiet 4000 KY- - - FLOODING

A couple things...

Valve adjustment...was mentioned previously. Regardless of hours, check them. Setting is .002" for both. Remove spark plug and use something such as a soda straw to feel the piston come up to top dead center as you roll it over by hand. Make sure the valve rocker studs are not loose and backed out a little. Inspect valve springs for breakage.

From your previous post where it started, ran, and you powered the AC for a bit, did it start and run by itself, or did you "doctor" it into starting initially? And if it did start by itself, am I understanding this is the only time it will start unassisted for the day?

Where do you have your altitude adjustment set to--"0"?

Have you tried grabbing the governor arm, and pulling it towards idle to see if it will run at a slower speed? Idle stop should be set so it won't run below 46 hertz or so, and it will shut off for fault code 13 (voltage at < 108 for 30 continuous seconds) or fault code 15 (freq. at < 54 for 30 continuous seconds)

You can also try attaching a length of clear hose to the drain, and drain back into a clean container. Drain is the little nipple down by the cut-off solenoid, and you crack the screw next to it to allow the few to drip through the hose. Find a rate of "drippage" that will the unit to run. This will allow you to run on the fuel pump/main fuel supply long enough to possibly make other observations that haven't become clear yet.
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