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How is the Onan 4000 Gasoline Generator (33 amps) Wired into 50 amp Coach?

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jam4travel

Does anyone know how Phoenix Cruiser wires their Onan 4000 Gasoline Generator (33 amps) into a 50 amp service coach?  A 50 amp service Phoenix Cruiser has two separate 120 volt 50 amp legs that services the coach's electrical power needs. 

Is the generator wired to only one of the 50 amp legs?   

If its wired to both 50 amp legs, what are the volts and amps delivered to each leg?

This stuff is over my head!!!

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Free2RV

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Before we ordered our 3100 with 50 amp service, we asked Phoenix if the generator would operate either A/C separately or just the front (main) unit.  They had the electrician talk to us and he said it was wired to operate only the front A/C.  While Barry was doing our walk through, he started the generator and at that time we checked and only the front A/C would operate from the generator. 

Also, while we were camping at Elkhart, I watched the remote readout from the surge protector and it appeared that the only time that amps were being pulled off the second leg of the power cord was when the second A/C unit was running.  Hope this answers your question.

Gary

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jam4travel

Gary, Thanks for the information!!!!

John

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jatrax

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The generator is wired only to leg #1 of the 50 amp distribution panel.  So anything on leg #2 will only function if plugged in to shore power, not the generator.

We wanted 50 amps but have only 1 A/C unit.  We had PC wire the electric side of the hot water heater to leg #2.  So when plugged in we can use the electric hot water but when running the generator we must use LP for hot water.

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Doneworking

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We have a 2350 with 30 amp wiring.   I can tell you by experimentation that the Onan will not run the AC and electric hot water heater at the same time.   At least, mine won't do it.   I didn't realize until a few years ago how much efficiency is lost per 1000 feet elevation gain.   You can find the stats and curves on line but we often camp at 8000 feet + boondocking and sometimes we have trouble even running the convection oven with the Onan.   I don't know the oven's  amperage/wattage but I know if we don't let the generator warm up for at least ten minutes it will struggle with the oven.   

There is a little knob on the generator everyone needs to familiarize themselves with that adjusts for altitude.    Essentially, it just adjusts the carb like we used to do on old Chevys and Fords when we went to the mountains.   As I recall, a quarter or turn on the carb jet in my old Chevy would give me another couple of thousand feet up the mountain!   roflol

Paul
« Last Edit: June 27, 2018, 01:12:25 pm by Doneworking »

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Ron Dittmer

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There is a little knob on the generator everyone needs to familiarize themselves with that adjusts for altitude.

Paul
The altitude adjustment is never discussed on this forum.  I am glad Paul brought it up.

You have to open the PC access cover, then remove the Onan cover to get to the adjustment knob.  It is a crude adjustment.  I leave mine to sea level until above a mile high, then adjust as needed for smoother engine operation.  If having a hard time starting at high altitude, that is the first thing I adjust.
Ron (& Irene) Dittmer

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Doneworking

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Ron is on target about the adjustment being "crude".   You just have to experiment a bit if you are really up there in the mountains (8000 or more). 

Also, for some reason, occasionally  I have to "goose" my choke manually at high altitude.  That requires removing the access door and using my right thumb and forefinger to mechanically move the mechanism back and forth, holding it open while pushing the exterior stop/start button available on the front of the generator.   A real pain in cold or wet weather but it happens to me at least a time or two if we are boondocking for a week or more.   

Lets face it, Onan would not be our generator of choice if we had a choice.  If I were building my own rig I would put in a Honda or two and not suffer the noise.  Yamahas are also quiet.   The trailer guys with a little Honda 1000 watt inverter generator charge their batteries just fine and you can't hear the thing twenty feet from it...……...maybe forty feet for those with better hearing than mine.  The Onan 4000 has been the standard on Class C coaches for a lot of decades. 

Paul

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CalCruiser

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Has anyone ever installed a  manual fuel shutoff valve  to the carburetor, similar to the fuel petcock  on a motorcycle? If so, what part did you use? I am thinking that running the generator  out of fuel so the carburetor float bowl goes dry would eliminate the problem of storage and costly carburetor replacements ,due to the non-rebuildable design (thanks to the California Air Resourcse Board).

Sorry for the thread hijack
Goin' where the wind goes...

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Cropduster

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Keep in mind that with an increase in elevation there will be a drop-off in generator output.
Attached image is from the Onan Microquiet 4000 Generator, series KY.



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Joseph

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Calcruiser, this crap ethanol fuel is murder on carbs. On top of that the fuel just goes bad after a couple weeks. If my unit is going to be stored more than two or three weeks I treat my fuel with one ounce of sea foam for every gallon of fuel. I then run the gen to make sure the system is treated. I use sea foam over products like stabil because sea foam cleans your system as well as stabilizes your fuel for storage.  The one time I forgot to do this my pc sat for two months untreated and my carb was gummed up. As you know the carb is about $ 300 and can not be rebuilt. And if you can’t do the work yourself add another 150-200 for labor.  However I found a work around. My gen would not start at this point so I removed the spark plug, cut the fuel line to the gen and submerged it in a container of sea foam and hit the start button. Once I had sea foam pumped thru I let it sit for 2 days. Now with the hose reconnected I pumped fuel into the system using the starter, replaced the plug and hit the starter again. Oh it spitted and sputtered for a several mins, but then leveled off and runs like silk.

Side note, before cutting the fuel line I used a clamp to shut off the fuel so I wouldn’t drain the tank. I obtained a brass splice at Home Depot along with hose clamps and all is good.





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Joseph

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Done working, I agree a Honda or many other brands would prob be my choice as well but not one of those inverters you mentioned. I’ve seen people have two running Honda inverters parallel and they are quiet and work great. However they have a short life span so imo they are not a viable option.

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CalCruiser

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Thanks Joseph

I am going to order a  Motion-Pro 12-0035  from  Summit Racing. The  discontinued (why?) Onan 4C foaming  aerosol carb cleaner  was the good stuff  :'(
Goin' where the wind goes...

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Joseph

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Cal crusier,  curious, do you know if these carbs, fuel pump and filter  need to be stored wet? I considered exactly what your looking at and running it dry before shutting it down but wasn’t sure about those items. That and I still need to treat the gas if I store the pc.

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Doneworking

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I guess I have just been very, very lucky.   I normally burn 10% ethanol gasoline and the generators on my various rigs over the last thirty or so years (Onan and Generac) have always provided good service and have never given me a problem.  Like I say, probably just dumb luck BUT I do run them under load for between one and two hours every month without fail.  I start them up and let them warm for ten minutes, put under a good load and let them run under that load.  Then, I remove the load and let the generator run with no load for about fifteen minutes to cool it effectively.   I change the oil before it is time to do so and I make sure the air cleaner is in top condition.   Other than that, I just never have had a problem. Lucky.

Paul

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CalCruiser

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Cal crusier,  curious, do you know if these carbs, fuel pump and filter  need to be stored wet? I considered exactly what your looking at and running it dry before shutting it down but wasn’t sure about those items. That and I still need to treat the gas if I store the pc.

That's  a really  interesting thought! Do you know if the 3 psi electric  fuel pump runs constantly while the generator  is running, or if the fuel flow  becomes gravity  fed  once prime is  established?

Since there's no internal vacuum diaphragm pump  in the carburetor, the float bowl should go  dry if 12V to electric pump is switched  off while the engine is running, unless it is gravity fed. Disabling the fuel pump with a remotely mounted  toggle switch would also eliminate any possibility that back pressure created by a mechanical shut-off valve  on the output side  might damage the pump.

The shut-off solenoid at the bottom of the Onan 4000 KY series float bowl activates a needle valve in the carburetor body that shuts off fuel entering from the float bowl. The tiny passage from the needle valve  to the jet gets gummed up. The only way to prevent that is to use up all the fuel in the float bowl while the needle valve is open so  negative pressure in the intake manifold and carburetor can suck the jet and passage dry.
« Last Edit: June 30, 2018, 03:00:23 pm by CalCruiser »
Goin' where the wind goes...