Could it be a Carburetor Problem?
Photo A.) Pencil shows the area of the housing that you need to check for Side Slack. Side Slack is caused by the shaft that enters the Carburetor at this point. It's the shaft that's wallered out the hole where it enters the Carburetor. There can be a small amount of play but you'll know it if there's to much. A broken or missing return spring can cause this.
Photo B.) A clear Photo of the correct position of all the linkage. The linkage has to be removed when the Carburetor is replaced. Sometimes the linkage may not get put back in the same position it was in before it was removed.
Photo C.) Pencil is pointing to the Fuel Line entering the Carburetor from the Pump. Here you see a standard Hose Clamp on the Fuel Line. This is an indication the Carburetor has been replaced. The Band Clamp from the factory has to be cut off when the carburetor is removed, you can't take the Factory clamp off with a wrench. The Factory Band Clamp is replaced with a Standard Hose Clamp that will accept a screw diver or nut driver.
My Generator is running but I have no electricity in my Living Quarters
*** First, - check to see if the Breaker is ON or OFF. The Breaker is located on the Generator. If you have the popular Onan 4000 gas or 3600 LP Generator, if the Breaker Switch is towards you, it is in the ON position.
You can't see the Switch in this photo, but the Pencil indicates the approximate location.
This photo also shows the Start Switch on the Generator.
*** Second - See also, - Electrical >> ATS Switch Defined
My Onan Gas Generator runs "Ruff" or it runs for a bit then quits.
If your Gas Onan runs "Ruff" and / or it runs for 30 min or 2 hrs and then shuts down.
First, check to see which Fault Code is displayed, - see in this section >Onan Fault Codes<
1. At the time it shuts down, check to see if there's a spark present at the spark plug. It could be that the Ignition Coil is going out, or the Spark Plug Wire has a bad spot in it. If you determine there is no spark, or sometimes a spark, the Generator has to be pulled to get to the Coil.
2. The other possibility is worn out linkage at the carburetor. There are two Butterfly's in the Carburetor. Check the top butterfly linkage and make sure the post coming up from the butterfly does not have a lot of side slack in the hole going into the carb, it could be wallered out by sloppy linkage. This would require a new Carburetor. $200 to $300 depending on who fixes it. ( see Photos>Troubleshooting>Onan Carburetor )
3. If your Gas Generator runs, but runs very ruff. More often than not, it needs a new carburetor. It has sat for a long period of time without running and varnish has started to build up in the carburetor. There's no cleaning it. You could try running a couple of gallons of carb cleaner through it, but you'll end up replacing the carb. Onan recommends running a Generator at least 2 hrs a month. The periodic use of a Fuel Stabilizer which keeps the fuel fresh, is recommended by Onan
4. If your Generator is mounted on top of the trailer, there should be 2 fuel pumps. The 4000 Onan has one Fuel Pump at the Generator and who ever installed it should have added a second pump somewhere below the top of the trailer. It needs that second pump to get the fuel up. Put your hand on the 2nd pump while priming it, or if the generator is running - you should feel a slight vibration from the pump if it's working. If not, check to see if 12 volt is present at the pump. One wire is ground and the other is hot, 12 volt DC. ( see, Generators > Fuel Pump Locations )
5. If you hear a sharp clicking from the pump, or if it clicks sometimes and then not, - it could be the pump is beginning to fail. Every time you hear the clicking, fuel is not passing through the pump. That's why when you start to prime it, you may hear it clicking and then the clicking stops. That's because fuel is finally passing through the pump and you shouldn't hear any more clicking if everything is operating correctly.
6. If your Generator's been running ok and it quits and it won't even try to start again, the Battery may be Dead. Charge the Battery and try to start it. If it starts, it will run until it's drained the Battery and then it will shut down again. The problem is the Battery is not recharging while the Generator is running. The Generator needs 12 volt to run. It does not recharge it self and it won't keep running if you disconnect the battery.
Note: The are a couple of ways to keep the battery that starts the generator recharged.
One way is from the Converter inside the Living Quarters. The Converter acts like a Battery Charger. 120 volts AC comes from the Generator to the Converter, then 12 volt DC goes from the Converter to the 12 Volt DC Battery.
Another way is from a regular Battery Charger. The Battery Charger might be plugged in to a 120 volt AC receptacle on the trailer and hooked to the Battery. While the Generator is running the Battery is Charging.
My Onan Gas Generator won't start
If your Onan Gas Generator will not start. ( see also, Generator / Fault Codes )
1.) First, is it getting gas? Remove the rubber fuel line hose at the carburetor and try to start it. Fuel should be spurting out of the hose.
2.) If you're not getting fuel. It may be a bad fuel pump which is located in the Generator Compartment. If you hear a sharp clicking instead of a dull thuding sound when you are priming the generator, it may have a bad fuel pump. It is natural to hear a sharp clicking when you first start to prime the generator, but if everything is working correctly the sharp clicking turns to a dull thuding sound when fuel reaches the pump.
3.) Is there a spark to the plug?
4.) If your generator has sat idle for several months without running, and it turns over but won't start, the gas could have varnished up inside the Carburetor. There is usually No Cleaning the Carburetor, it has to be replaced. Periodic use of a Fuel Stabilizer that keeps the Fuel Fresh is recommended by Onan.
5.) Does it start at the Generator but not from the Living Quarters if so equipped with an additional start button? Then the problem is between the Generator and the additional start button inside the LQ.
6.) If your Generator's been running ok and it quits and it won't even try to start again, the Battery might be Dead. Check the Water and then Charge the Battery. If it starts, and if the battery is no good, it will run till it's drained the Battery and then it will shut down again. The problem is the Battery is not recharging while the Generator is running. The Generator needs 12 volt DC to run. It does not recharge it self and it won't keep running if you disconnect the battery. ( see also, Electrical > Converter > How do I troubleshoot the Converter )
7.) It could be that the Positive and Negative Cable on the Battery needs to be cleaned to make a better connection. Simple, might try this first. Just because the cable is on the battery post does not mean it's making a good connection.
This is how the Battery that starts the Generator charges:
The Converter (if equipped) inside the Living Quarters acts like a Battery Charger. 120 volt AC comes from the Generator to the Converter, then 12 volt DC goes from the Converter to the Battery that starts the Generator.
( see, Electrical > Converter > How do I troubleshoot the Converter )
8.) If your Generator's been running fine, and if the next time you try to start it, you just hear a clicking sound. Remove the Negative Battery Cable from the Battery that starts the Generator, and you can do this at the Generator also. With the Panel Door off the Generator, use your left hand and reach through the Generator on the Left Hand Side until you find the Fly Wheel. Spin the Fly Wheel to make sure it's Free. Then hook up the battery cables and try starting again. Sometimes when a Generator shuts down, it stops at an exact point at what I'd call Top Dead Center. You just have to move it slightly off top dead center and then it's ok.
Onan Fault Codes
The Start / Stop / Prime Button will Blink out a Fault Code if the Generator quits running or won't start for whatever reason. The Fault Codes and what they mean are Listed in the Owners Manual.
This is how you read a Fault Code.
1. If you'll look at the Start/Stop Button when the Generator stops running, it will be blinking, there will be a pause and then it will blink the same number of blinks again. Count the Blinks. 3 Blinks indicates a Service Fault. Press Stop and it will start blinking again. What you're looking for is a two digit code. 3 Blinks was the 1st Level of the code, pressing Stop will give you the full code. Example, when you press stop, you'll see, blink, blink, blink - pause - blink, blink, blink, blink, blink, blink - pause, and the blinking repeats it's self. So what code did it blink out? Right 36.
The first set of Blinks that you see when the Generator stops "is" the first Level of the Code, or in the upper example 3. Don't misread the first level blinking as being a 33 or 44. For this reason there is not a Fault Code 33 or 44.
First Level Fault Codes are 3 and 4.
Fault Code 3 is a Service fault. From here you'll look for the second digit code.
Fault Code 4, is caused by Over-cranking.
Now, if you've been gone and when you get back and the generator has stopped running, the Start/Stop Button will not be blinking. It quits blinking after 5 min. To get the Fault Code, Press Stop 3 times within 5 seconds and the blinking will start. You just need to count the First and Second Level Blinks. Example, blink, blink, blink - pause - blink, blink, blink, blink, blink, blink - pause - and it repeats. If you hit stop again, the blinking will Stop.
What could be the problem if my Gas Generator is Surging?
Your generator should run at a level and constant RPM. If it revs up for a moment and then ruffly idles down and then revs up again and so on, it's surging or what we might call hunting. If it's surging, the electricity that it produces will not be constant which can effect the appliances in the living quarters. A good indication is to listen to the Roof Air or the furnace fan while they're running. They will surge with the generator.
If the Generator is surging to much, - when you turn the AC on the generator dies, as mine did. If yours dies, check the fault code. Mine was blinking a 14 which means, take it to an Onan Service Center.
More often than not the cause is a varnished up carburetor. Which means the fuel has set in the carburetor too long due to not running it often enough. Onan recommends running it 2 to 3 hours a month, or using a fuel stabilizer in the fuel to keep the fuel fresh.
The normal fix is replacing the carburetor.
But, you might try this first. It doesn't work that often but it might save you a trip to the service center and a couple of hundred dollars.
I can't say for sure which part of this fixed it, I just know this is what I did.
At the Parts store, get 1 Pint of "Sea Foam Motor Treatment for Gas and Diesel Engines". One Pint treats 8 to 25 gallons. I put in 8 oz (half the can) per 8 gallons.
At the Parts store, get one aerosol can of "Sea Foam Deep Creep" - and if the Air Cleaner hasn't been changed in a while, have one of those ready. (see Onan Part Numbers) in this section.
1st - Check the Oil to make sure it's ok, and then Remove the Air Cleaner. ( see photo A & B ) Take a rag and wipe out the air cleaner housing so no dirt gets sucked into the carburetor.
2nd - Start the Generator. With the Deep Creep, spray through the air cleaner housing into the carburetor for about 4 to 5 seconds. You can look in the housing to see if your spray is going into the throat of the carburetor. The generator should rev up and stabilize for a minute or so before it ruffly idles back down. Each time it idles back down, spray again for 4 to 5 seconds. Do that about 8 to 12 times.
3rd - Next, locate the Altitude Adjustment Knob on the carburetor. With the unit still running, use your index finger on both hands (see photo C & D) and move (rotate) the Altitude Adj Knob all the way in each direction, back n forth, back n forth - about 3 dozen times and stop with the knob indicator close to whatever your altitude is, 2,500 ft is about half way between 0 and 5,000. Doesn't have to be exact.
Hopefully at this point you'll notice your generator starting to run longer at the higher RPM without ruffly idling back down. If you do not notice a change or maybe you noticed a slight change but it's still not right, repeat everything again starting with spraying into the throat of the carburetor.
If you think it helped, PUT THE COVER DOOR BACK ON THE GENERATOR AND let the Generator run for an hour. After an hour, put the Air Cleaner back on. After another 30 min turn the AC on and leave everything on for about 2 hours.
If this made no difference at all, more than likely it's going to need a new carb, but a second opinion would be good. There is no cleaning the carburetor and they don't make kits for 'em.