Generator bogging with AC

xtracrispy

xtracrispy

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Having a problem with the generator in my toy hauler. It ran like crap when we bought it since it had a China carb in it. Put a brand new Onan carb in and it seems to run good now. 

problem is about 75% of the time you switch the ac on, it Boggs down like it has way too much load. Put new OEM capacitors in the ac(one was leaking oil) and that didn’t make a difference. Ac works fine on shore power. 
 

generator is an Onan Microquiet 4000, ac is a domestic 13,500btu, both original to the trailer. 

Any ideas what to look at next? 
 

 
Still Sounds like a fueling issue. Gas or propane? Did you flush tank/lines, change fuel filter?

 
Sausage450r said:
Still Sounds like a fueling issue. Gas or propane? Did you flush tank/lines, change fuel filter?
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Thanks, forgot to mention. Pumped all the old gas out, and has 2 month old gas. New fuel filter. 
Gas powered, runs off the fuel station tank.

For clarification on the issue. Maybe lugging is better to say bogging. 

If it was a bike I’d say it sounds like you’re trying to pull a hill in too high a gear. it’s trying but doesn’t have the power to “pull”

 
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is something else drawing a bunch of electric. like the onboard converter charging the batteries. could put a meter to see if the voltage and frequency is correct i think its 120v and 62ish htz. if the frequency is low the ac will draw more amps. the frequency is directly tied to the rpm of the engine   also could check the amp draw 

 
I read a thread years ago on irv2.com, glamisdunes.com but for RVers, and it said to get a better AC capacitor. Also helped when using a Honda 2k or 3k generator instead of the onboard genny. 

My 5 year old home AC wouldn't start a month ago and it was a bad capacitor. It was working fine but not enough to start the compressor. My HVAC buddy added a 'booster' capacitor and it's been running fine ever since.

 
L.R.S. said:
I read a thread years ago on irv2.com, glamisdunes.com but for RVers, and it said to get a better AC capacitor. Also helped when using a Honda 2k or 3k generator instead of the onboard genny. 

My 5 year old home AC wouldn't start a month ago and it was a bad capacitor. It was working fine but not enough to start the compressor. My HVAC buddy added a 'booster' capacitor and it's been running fine ever since.
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This makes alot of sense. 

 
Soft Start for the AC may help, also. When you say it lugs/bogs, does the governor snap the throttle open when the load is applied, but the engine can't pull the load? Have you checked valve lash?

 
1HasBeen said:
Soft Start for the AC may help, also. When you say it lugs/bogs, does the governor snap the throttle open when the load is applied, but the engine can't pull the load? Have you checked valve lash?
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Good point on the governor, haven’t looked, I’ll check it out. 
haven’t checked the valves either. 
 

AC has new capacitors. One is a dometic “hard start” capacitor, their claim is you’re supposed to be able to run my AC on a 2000w Gen. To be honest I’m not sure how it’s different than the more expensive “soft start” systems. 

 
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What does your voltage  read with and without load?

some muti meters can read hertz try to see what that is   Genset rpm might be off

 
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If you haven’t seen these videos Go to YouTube and search this:

1.       Onan Microquiet won’t start

2.      Updated Onan Marquis Gold 5500 Generator how to stop surging. 

Hopefully this helps. 

 
Low cost easy thing to check: inspect fuel lines for cracking. On my WW mine would run like that. Found some cracks in the old fuel line near the tank, was sucking air fuel combo and would run just hard starting and low on power. Replaced a small section of fuel line, good to go.

 
1HasBeen said:
Soft Start for the AC may help, also. When you say it lugs/bogs, does the governor snap the throttle open when the load is applied, but the engine can't pull the load? Have you checked valve lash?
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i just bought this one. https://www.amazon.com/ActiveStart-Softstart-Conditioning-Reduces-generators/dp/B0BL1N2BZD

its pricing but i like the feature of bluetooth to see how many amps im pulling since im new to this game. now i know that my ac draws 16amps , all lights on with tv pushes me to 17 amps. but my 5th wheel had a bad gennie and it was removed so i put in a sliding tray and used the cheap harbor freight 4500 inverter generator, and so far so good. and seems to be really good on gas.

 
Is the altitude adjust working properly? Maybe she’s a bit rich at 3900’

 
I had same problem.  The plug in the box with the power cord wouldn't stay in. Replaced the female receptacle and all was good. Everything seemd to work fine until the load of the AC hit.

 
Why not put a weddle supercharger on it and call it a day….🤣

…. I’m all honesty.. I’ve been ‘arguing’ with generators my entire life .. they can be a real mutherfukker at times..

abc

 
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Did it not have a issue before,  Is this the original AC,  

My understanding the 4000 can run Two 12,500, I would check to see if the 4000 can run dual 13,500  

I thought the 4000 was a 30-amp unit and the 5500 is a 50-amp unit,  

 
Thanks for the suggestions so far, I'll start looking into some of them next chance I get. 

J Alper said:
Did it not have a issue before,  Is this the original AC,  

My understanding the 4000 can run Two 12,500, I would check to see if the 4000 can run dual 13,500  

I thought the 4000 was a 30-amp unit and the 5500 is a 50-amp unit,  
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Original AC and Genny. Gen barely ran when I bought the trailer since it had a china carb, this issue I have only noticed since I got the gen running with a new OEM carb. 

 
Is it losing RPM, or just sounds like it's working hard?  Working hard is fine as long as it's not surging or dropping RPM.  

You also can't stop AC then turn it back on fairly quickly, needs to sit for 30 seconds or so before you can turn it back on.

 
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Rockwood said:
Is it losing RPM, or just sounds like it's working hard?  Working hard is fine as long as it's not surging or dropping RPM.  

You also can't stop AC then turn it back on fairly quickly, needs to sit for 30 seconds or so before you can turn it back on.
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that happened with my 4k onan the other day, actually stalled the generator.

waited about 5 minutes, restarted gen. and a/c worked fine after that.

has something to do with pressures in the a/c system?

 
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