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Old 10-15-2012, 01:21 AM   #15
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The kil a watt has a frequency scale too. You can set the RPM to get the proper 60 hz frequency and it should then give you the proper voltage and power output automatically. If not, there probably is some carb or other issue. As someone else said, usually not a generator side issue, but common engine problems. Note, I did say "usually".
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Old 10-15-2012, 08:45 AM   #16
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Just a few words of caution based on my experience with Onan gensets:

Standard power in the US is 120V @ 60hz AC. Our gensets are designed to run at 1800 RPMs for a reason. This speed is critical because it's what determines the AC frequency output. Modifying the engine speed will not only change the voltage but, more importantly, will change the frequency. The engine runs at a constant speed. The greater the AC load the more the throttle needs to open in order to maintain that speed. The AC voltage output is determined by this speed and the health of the generator assembly. When designed and built correctly, the genset will produce low load to full load power at this constant 1800 RPM speed.

Many electronic devices are frequency sensitive. If the frequency is good but the voltage is low then the issue is more likely at the generator side or beyond. It's common for slip rings to get oxidized when not used regularly. This will result in low exciter voltage and low output. This is why most generator companies recommend you exercise the genset once a month in order to keep the slip rings clean. Usually a simply cleaning of the slip rings will restore full AC voltage. Don't ignore the possibility problems outside the generator either. Dirty transfer switch contacts in the RV it self can cause low voltage.

Light bulbs, 3led testers and such will not give you a complete picture of what's happening. A relatively inexpensive DVM (Digital Volt Meter) that can also read frequency is a great investment for any RV/Motorhome owner. Test your genset at low medium and full load and exercise your genset regularly for at least an hour at 3/4 load.
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Old 10-15-2012, 08:55 AM   #17
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As 92landyatcht mentioned, I would set the throttle so the generator is producing 60Hz. Many volt meters can measure frequency and I would use that to set the RPM. I would check it at different loads as he suggested as well. An oscilloscope would tell you a lot about what is going on. Also as someone suggested, use something like a 14 gage or heavier extension cord for the polisher. A 16 gage 100ft long cord does not work well for heavy loads. A standard digital volt meter should work fine for your generator. The averaging errors are caused by modern inverters and they can produce square waves not sine waves. Your generator is an old analog type and it produces a true sine wave and should compare well to house voltage. Anything below 110V at full load is a problem. I would expect 120V with moderate loads.


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Old 10-15-2012, 11:17 AM   #18
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Great info guys!

Learning a lot here!
The generator motor needs further service by the sounds of it... I will say that recently it did not seem to be running at a consistant speed under load.

Will need to drop the M/H gas tank, and it may be out for a bit while I run thru the fuel system. But I need to be able to run the genset. For that reason I have added a T to the Genset fuel feed, with a switchable option.
This way I can run off the Main gas tank or a portable tank.
Like this;


As I posted in another thread here, I had a bad oil leak, and while I was curing that I put the whole thing on slides for future service work. I will maybe have to pull the whole thing out anyway to replace and improve the soundproofing. The fuel feed line from the main gas tank to the genset is a mess too, and I intend to do away with the 5'+ long rubber pipe that runs inside the compartment, and replace it with an hard line that will be either outside the compartment or at least insulated from the genset heat.
I also like these glass sided filters... Its nice to know and see that the fuel is flowing and what color it is... It was shocking to see the difference in color from the gas in the main tank to fresh gas pulled from the portable tank...
Also I think I will prep a tank of gas with a heavy dose of Seafoam and that will help clean the gum out of the carb and also maybe remove some carbon deposits inside the engine... It diesels sometimes on stopping it.
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Old 10-15-2012, 11:26 AM   #19
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Beware of ethanol flavored gasoline. It tends to mess up stuff with carbs especially if it sits. It also tends to attach rubber fuel lines. If you have to use it, run the carb dry before storing.

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Old 10-15-2012, 11:40 AM   #20
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Thanks Perry, and good points.
I have plenty of bad experiences with the E and fuel lines...
Here is CA we have about 10% in our gas I think, so no choice.

The fuel selection valve will allow me to run it dry too... all good!
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Old 10-16-2012, 10:31 AM   #21
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Agreed that the best way to store a gas genset is with no gas in the carb. A fuel cutoff switch is a good option. Bad gas fouling of the carb is the primary reason for a no start the next season. It's one reason that propane gensets seem to take long term storeage better then gas units. The only thing you need to check for after a long sitting with no gas is a stuck float. Usually a small rap on the float bowl will fix that.

Like I said earlier... Run your genset at least once a month to keep it in good shape. If not you risk a much higher probability of engine running and voltage issues later on. Keep a good dose of fuel stabilizer in at all times. By doing so you will keep stale gas varnish buildup down throughout the fuel system. Once you done your monthly run, then cut the fuel and let it run dry with no load.

If I try to start a genset that has sat for some time I'll drain gas out of the fuel line until I get good no stale gas flowing. I'll drain the float bowl and inspect it. If all checks out I'll then connect the fuel line and attemp a startup.
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Old 10-31-2012, 03:32 PM   #22
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I took my Killawatt over to the M/H...
But it refused to start.
Looks like the Facet fuel pump is the issue...
Pulled it out for some bench testing...
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Old 10-31-2012, 03:48 PM   #23
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Quote:
Originally Posted by 92landyacht View Post
Like I said earlier... Run your genset at least once a month to keep it in good shape. If not you risk a much higher probability of engine running and voltage issues later on. Keep a good dose of fuel stabilizer in at all times. By doing so you will keep stale gas varnish buildup down throughout the fuel system.
If you use fuel containing ethanol, varnish is the least of your worries. Ethanol is hydrophilic, and will bind to even the least amount of moisture in your tank. With small amounts of water, this is good. With larger amounts, especially coupled with changes in ambient temperature, the ethanol+water will separate out from the rest of the fuel, undergo a phase change, and turn into a sludge that is all but impossible to remove without disassembling the fuel system for cleaning.
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Old 11-21-2012, 01:39 PM   #24
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Just a quick update...
Cant get the onboard Kohler running.

I did however use an external 3500w genset, which I plugged the MH into via the power reel, and using the Killa-watt, adjusted that genset's output from 112v up to about 118v via the throttle linkage.

I was puzzled/worried when i tested the outlets using the yellow LED tester, that it was saying I have an "Open Nuetral" on all outlets...

How worrisome is this and where should I look?
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Old 11-21-2012, 02:24 PM   #25
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A redneck tester is a Kill-a-watt and a bunch of cube heaters. I fire up the genset and adjust the govn'r to acheive 60Hz on the KillerWhat. I then plug in enough of those small cube heaters (800-1000 watts each) to put 1/2 of the rated load on the genset. Then check to make sure the frequency is holding at 60Hz. The unit shouldn't even twitch at 1/2 load.

BTW, I don't plug all of thoses heaters into the Kill-a-Watt...that tends to let out the smoke in the Kill-a-watt

I have used a full load of heaters to simulate a maxed out genset, just assure you don't exceed the duty cycle (usually 80% of rated is a max load).

Your milage may vary, works best in the winter (ahhh, warmpth)
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Old 11-21-2012, 03:28 PM   #26
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Hi, it is very common on these generators to carbon up. This is mainly because of two things; Lack of use and a constant low RPM operation. You need to remove the heads and scrape off the carbon. Unlike a car engine, You can't rev the crap out of them or do a full throttle "freeway banzai run" to blow the carbon out. Removing the heads isn't a hard job except for removing the generator to gain access. My Onan owner's manual listed this as normal maintenance.
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Old 11-21-2012, 07:39 PM   #27
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honda

remove the onan, buy a honda, mount the honda in the hole, set it and forget it. keep the onan in case you ever sell the whole enchilada and someone wants to restore it. an inverter gen is way better than the old onan.
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Old 11-21-2012, 07:45 PM   #28
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remove the onan, buy a honda, mount the honda in the hole, set it and forget it. keep the onan in case you ever sell the whole enchilada and someone wants to restore it. an inverter gen is way better than the old onan.
At the risk of sounding rude...
I have a Kohler.
Send me the money for the Honda and I will put it in, otherwise please be sensible and keep reminding yourself that not everyone has a budget for that.

Now, back on track.
Maybe I am carboned up, and a decoke is a good idea for the medium future, as I will be pulling the genset out to redo the soundproofing.

Any thoughts on the Open neutral issue?
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