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oneway

Onan 5500 Issues

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Hi folks, bear with me for a minute while I explain the situation and hopefully someone will have some input to help:

My Onan 5500 starts and runs. It will run 1 A/C but when I put on the 2nd A/C it bogs down and kicks it off line. When I am plugged into shore power there is no problem running both A/C's.

I have a 30 amp coach with the Intellitec system that sheds the loads between A/C for start up.

We are in Yuma until April and I called out a tech who looked at it and said the gen is blowing some oil out the vent tube and declared the genset had to come out and be rebuilt. My problem with the diagnostic is that he never checked the electrical output or compression or any other technical diagnosis other than starting it and observing. He thinks it's a piston ring or a valve. Wouldn't a ring problem show up in blue smoke and oil usage? It did blow some carbon on my hand on startup until warm, then quit as I held my hand near the exhaust.

The tech wanted us to drive the RV to the shop for removal so we went by the shop with the toad and it was nothing more than a small parts store, so I asked about the "service area" and I was told that they would remove the genset in the alley and rebuild it on a bench behind the store. They "do it all the time".

Also, no price estimate. 

I'm really not comfortable with the situation. We are on shore power and fine for now so I have time for some good input to make a decision. I ran the Gen and 1 A/C yesterday for about 3 hours with no problem.

We certainly can wait to get a better handle on the diagnosis and costs.

Thanks

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Go with your feelings.  They are not often wrong.  If something just doesn't feel right there is likely a good reason for that.  I would get a 2nd opinion and I would absolutely require a written estimate before I did anything further.

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I can't recommend the rebuild yet either. What amp load does your Intellitec system show when running one AC? Have you tried to add outher loads besides the 2ed AC? Try adding some loads like a small heater, start on low and see what the load is on your Intellitec system and if the generator can handle it and the AC. Then go to hi setting on the heater and see what the readings are on the Intellitec system and let us know what they are. 

Add on thought. Try running the second AC by itself and see if it will run and what the amp load is. I had the stray thought it could be a problem with the second AC possibly a bad start capacitor causing a heavy load at startup.

Bill

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I have not looked into any of the newer coaches that have intellitec, but from the older days a 30 amp coach would not even run both AC's on 30 amp shore power, in the old school, you had to crank the generator to run the second one. But with that said, if 30 amp shore power will run two AC's, then a 5500 watt generator should have no problem running them, as 5500 watts is almost 45 amps @ 120 volts. As jrock stated, a clogged fuel filter, or a near clogged air filter can produce a loss of power. The only observation by the tech may have made to concur that it needed rebuilding, is that a compression test revealed too low compression, which can be caused by bad rings, or bad valves, or poorly adjusted valves.

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Were it me, I would continue on down the road.  One A/C should get you by until you get to a qualified/Onan authorized repair facility.  In fact, I would start by calling Onan, discuss your route and ask for their input on where to stop for diagnosis and possibly repair.

Yes, it could be serious, but could also be something inexpensive that is keeping the engine from putting out full power-- clogged air or fuel filter, varnish in the carb, valves out of adjustment, etc.

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I went in the Onan website and this place is a certified Onan repair station. And the intellitec control panel doesn't show an electronic readout of amp loads either.

I think I'll start with new air and fuel filters. The coach did sit for about 4 months while they replaced the roof without any attention to exercising the gen.

Now, correct me if I'm wrong, but wouldn't a bad start capacitor show up on shore power as well? My initial thought was a bad start cap but then I have no problems on shore power.

 

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Yes a bad start capacitor would show on any electric service, and once started the start capacitor is not in use anyway. You might want to try to use a separate fuel container to test run the generator just in case the fuel has lost some octane, I'm assuming that it is a gas generator,and you have stated that the coach sat for four months. The coach motor may not affected as much as the generator because of more cylinders  and the electronics on board.

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Yes if the second AC starts good on shore power then that eliminates that possibility. Hard to diagnose things remotely. Yes running a rich mixture of seafoam using a separate supply like a gas can can't hurt.

The blowing carbon on your hand could just be caused by the choke making it run rich till it warms up and cuts the choke off.

Bill 

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Alright. Thanks to all I have a few things to try. I'm not familiar with sea foam. I'll do an internet search for that product. I did see something on the net about slip ring cleaning and I'm not familiar with that procedure either.

I can say the coach has had probably 4 full tanks of gas run through it since the sitting episode for the roof replacement.

and the genset has always started and run.

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I am a newbie to motorhomes but have some experience with generators.  Isn't a 5500 too small or marginal at least for (2) ac's??  I have a 5,000 in my fleetwood with one ac unit and it bogs on startup.

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Just a thought but the gen set has 2 outputs the ac units should be connected to opposite outputs if they were inadvertently connected to the same output they won't both run at the same time 

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Actually if one output is drawing too many amps, then the circuit breaker on the generator should be tripping instead of bogging down, unless someone has put too large a breaker, or has defeated the breaker somehow. This leads me to believe that something has gone awry with the genset, as stated in post's by others above. 

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10 hours ago, dewflicker said:

I am a newbie to motorhomes but have some experience with generators.  Isn't a 5500 too small or marginal at least for (2) ac's??  I have a 5,000 in my fleetwood with one ac unit and it bogs on startup.

Welcome to the forum. There are a lot of variables involved. The newer AC units don't draw as much current as some of the older units. They also start by starting the fan before the compressor so the load at start up is less. I was surprised how low the amp loading on my load center display was running both. I think it was only about 22amps.

Bill

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I has a 5000 w Kohler gas generator on for last MH and it ran two 13,000 btu air conditioners OK if I kept the generator tuned up.  I changes the spark plugs, fuel filter and air filter annually.. The coach wiring prevented from running both AC units when connected to a 20 amp circuit.

 

 

Jim

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Yes the genset normally runs both the A/C just fine. I have owned the coach for 12 years. As stated in the long initial write up, the intellitec system sheds the startup load with the other A/C and handles both once started with no problems. It's a 30 amp coach. This was fairly common on Fleetwood products. Mines a 2001 35R.

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oneway, did you ever try the gas can test that I suggested earlier?

If you have owned the coach for 12 years, the fuel line may well have broken down, and partially stopped up, or a pinhole developed, allowing air to be pulled into the fuel. Either of these conditions will show up under heavier loads.

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