Onan 6500 watt generator

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quadrider

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Jun 23, 2008
Posts
326
I have 1989 bounder with onan 6500 watt gen

Went camping this weekend and the the onan kept tripping one of the breakers on the generator. Before I could run two heavy load items off the generator. I could run both ac at once or i could run one ac and something else that draws lots of power like my charger or a microwave. Now she will only run one heavy draw item. I have tested all the heavy load items one at a time and the generator has no problem but as soon as I put a second load on the generator its starts to shake and then the breaker pops and the generator runs smooth again. Last time a talk to onan they told me they don?t work on the old units anymore so any ideas or info on what to check would be a big help.
 

Purple Frog

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Joined
Feb 10, 2009
Posts
23
Location
Havana Florida
I'm assuming your genset has two breakers.
You said one trips with both A/C on.
When that breaker trips which A/C turns off.
That may be a clue.
One of your A/C units may be going downhill and pulling a ton of current.
Things on that rig are almost 30 years old.
Just a thought.
 

darsben

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May 30, 2018
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2,201
Location
Central NY in summer beautiful Casa Grande AZ in w
I would check the capacitors first  and then  the coil (for dirt). A bad capacitor will increase starting draw as will a plugged up coil on the roof (but not like a bad capacitor. I might also invest in a hard start capacitor for the unit that is tripping the breaker. If the A/c's are exactly the same trade out the capacitors and see what happens. If problem stays the same then it was not the capacitor. If it goes away or moves then replace capacitor and clean the coils.

There are plenty of places that will work on the genny but I think you have a a/c problem.

Also how about creating a signature that lets us know what you have 1989 Bounder is nice but what chassis and where you are located. Someone may have local knowledge about where you can take the rig or where to avoid.

what A/C do you have?
 

Gary RV_Wizard

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Feb 2, 2005
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73,527
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At our Silver Springs FL home
At this point its hard to tell if the problem is an a/c or the genset. Does it make any difference which of the two a/c units you run first?  Is it always adding second /ac, regardless of which physical unit , that causes the genset to stumble?  Does one  a/c plus some other heavy load do the same thing (I think you said that, but want to double-check).  What else is running, e.g. fridge or water heater in 120vac mode? They cycle on/off via their thermostats and can add substantial power draw.

The genset has to increase power as loads are added, so it has a governor that responds to the electrical load and opens the throttle. If the governor doesn't work, or the engine doesn't increase its power on demand, then the extra amp load will cause the genset engine to slow down and stall.  It's not uncommon for gensets to have carburetor, fuel pump, or fuel line problems. Especially old ones like yours.  Fuel lines crack, pumps gradually lose capacity, and the carburetor gets clogged with a film of dried up gas if not run regularly.
 

quadrider

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Joined
Jun 23, 2008
Posts
326
I ran the front AC with nothing else on for 3 hours and the generator had no problem. I turn off the front AC and turn on the rear AC and ran it for 3 hours with no problem. As soon as I add a second load to the generator it starts to shake , the breaker on the generator trips and the generator runs smooth again. That second load item can be the other AC or it can be something plug into and outlet like a coffee pot or charger.
I have turn off all electronics and have turn off all equipment. Its like the generator has been reduce from a 6500 watt to a 3000 watt. I've own this RV for over 10 years and I could always run 2 heavy load items along with normal small draw electronics like TVs,radio, lights. I will manually rev the throttle on the generator tomorrow with no load and see if the generator starts to shake. That should eliminate or confirm a carburetor or fuel problem.
 

quadrider

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Joined
Jun 23, 2008
Posts
326
I check the generator tonight and it ran fine at full throttle. I haven't done anything with the generator but it has started to work normal again. I ran both ac for one hour with no problem. Could a hot day cause the generator to act up . The temperatures during the camping trip was 35? Celsius or 95 Fahrenheit.
 
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