Cummins Onan Generator won't start?

[humblegoe]

Won't start, tried removing the carburetor and cleaning the carburetor, major pain in the butt but went sort of ok, still couldn't get it to start, read somewhere that you couldn't rebuild these carburetors but instead had to replace them at a cost of about $350. Is that right and what do most folks here do about the generator issue? Also how much gas needs to be in the fuel tank in order for the Generator to get it's supply? 1/4 tank of gas ok?

These Briggs and Stratton generators run forever, years and years but the Onan if you don't start it up every month or so, carburetor plugs up. Don't understand that.

[KFX450RXC]

I'm no expert. But here's what I'd do. That doesn't mean I'm recommending to you. Could be dangerous.

But I lover ether. A little starter fluid has revived some of my landscape equipment many times. Your 1/4 tank may also be the issue. I can't remember if its the generator or the external pump that stops around 1/4 tank.

My Onan runs well but as you said, I start it every month or so and the fuel always has stabilizer.

[A32Deuce]

You need a minimum 1/4 tank. Maybe more/less. Put 5 gallons in the tank and try again.

[avid108]

We just had a problem getting ours to start, too. After changing the spark plug, using ether, etc., it still wouldn’t start. It turned out to be the generator’s oil level. Although it was on the stick, it was on the low side.

We added some, and it still wouldn’t start initially. Tried again later that afternoon and it started right up. Apparently the sensors needed to think a little bit about the oil level, even though the stick said full.

[sasch]

I have begun using Recreation gas (100% gasoline (no ethanol) designed for marine use) in "all" my small engines including generators. I still use stable but not as important when the ethanol has been eliminated. Since making this change my starting problems have been eliminated. Should mention I also start and run all my generators for 30 minutes at least once every 2 to 3 months.

[Hi Rider]

Had a similar problem when my RV was new. The problem: low oil. Put more oil in and the generator started just fine.

[F.R.O.G.]

If the issue is low fuel -- and at 1/4 tank it could well be, especially if you're not level and the generator's feed line is on the "shallow" end -- then after you add fuel you'll need to prime the generator. To do it, instead of pressing the "start" button, press the other side of the toggle switch and hold it for about 30 seconds, then try starting.

[Harkerr]

I helped a friend with this problem. Problem turned out to be. gum in carb float valve from inactivity Took it apart and cleaned it with choke cleaner. Problem solved. You could also take carb to a small engine shop to clean it.

[transmission_doctor]

Gasoline deteriorates over a fairly short period of time so Stabile is mandatory for any tank that is not used and replenished within a few months. Ethanol makes things worse. Just going to fuel without ethanol will not stop the deterioration. When I had my shop we had a car come in that had fuel in the tank but would not run. Fresh fuel fixed it. Fuel that does not have Stabile in it will evaporate in the carb and form an almost impenetrable varnish. I have had to physically scrape it off. BG44K will dissolve it, but it takes time.

Always use Stabile in your fresh fuel that is going to sit around for a while.

[aircommuter]

I use an ultrasonic tank for cleaning carbs these days they have too many plastic parts that are not removable. The old chemical dip I used for 35+ years destroys the plastic. The problem with having your oil low on the stick is when engine is cold and you start cranking it throws the oil around inside and it doesn’t drain back fast enough to cover the sensor. So it thinks it is even lower. No reason to check it and not add while you are there if needed.

[BobHanke]

Are you trying to start from the generator itself or by a remote start switch inside? Usually hold the switch down to prime until the light in the switch comes on then go up to start. Takes me a couple of times when not run for awhile or batteries are low. The remote start wire had to be replaced when we bought our rig used.

[formerFR]

I've experienced several times when the tank fell below 1/4 before I was able to fuel up, EVEN without having run the generator - what I've found is that the fuel tube for the generator will then allow fuel in the tube to run out, while the tank is below 1/4, which causes air to then be a problem when you try to start the generator.
The generator will then take much longer to prime, before starting, and may even stop within 30 seconds or so because more air is still in parts of the fuel tube... give it a crank again, and usually the generator will run from then on for as long as you wish.

[Wolverine 1945]

Originally Posted by humblegoe

Won't start, tried removing the carburetor and cleaning the carburetor, major pain in the butt but went sort of ok, still couldn't get it to start, read somewhere that you couldn't rebuild these carburetors but instead had to replace them at a cost of about $350. Is that right and what do most folks here do about the generator issue? Also how much gas needs to be in the fuel tank in order for the Generator to get it's supply? 1/4 tank of gas ok?

These Briggs and Stratton generators run forever, years and years but the Onan if you don't start it up every month or so, carburetor plugs up. Don't understand that.

I hear ya,,, 0 put $800 in ours year before last !!!
New Carb, on one trip & a new fuel Pump later the same year !!!

USE IT OUR LOOSE IT !!!

[Kirk S]

Originally Posted by sasch

I have begun using Recreation gas (100% gasoline (no ethanol) designed for marine use) in "all" my small engines including generators. I still use stable but not as important when the ethanol has been eliminated. Since making this change my starting problems have been eliminated. Should mention I also start and run all my generators for 30 minutes at least once every 2 to 3 months.

X2. I learned the hard way that portable gasoline powered equipment and gasoline that contains ethanol are a bad combination.
I keep ethanol-free gasoline on hand for that equipment.

The OP, from what I can tell, has a Sunseeker Class C motorhome so it would be very expensive to use ethanol-free gasoline, if not completely prohibited. Where I live, "marine gasoline" is not taxed for road use.

My solution has been to fill up at the end of a trip with regular ethanol type gasoline, add fuel stabilizer to the 55 gallons in the tank and run the generator monthly.

So far I've had no issues and with a full tank we're ready to bug out if necessary.
I considered only storing with a partial tank to save on stabilizer but read that the upper part of the tank could rust and cause fuel pump and filter problems.
Sea-foam is less than $7 for a 16 oz bottle at Walmart so it costs less than $28 to treat the gasoline for storage. Cheap insurance.

[Wolverine 1945]

Originally Posted by Kirk S

X2. I learned the hard way that portable gasoline powered equipment and gasoline that contains ethanol are a bad combination.
I keep ethanol-free gasoline on hand for that equipment.

The OP, from what I can tell, has a Sunseeker Class C motorhome so it would be very expensive to use ethanol-free gasoline, if not completely prohibited. Where I live, "marine gasoline" is not taxed for road use.

My solution has been to fill up at the end of a trip with regular ethanol type gasoline, add fuel stabilizer to the 55 gallons in the tank and run the generator monthly.

So far I've had no issues and with a full tank we're ready to bug out if necessary.
I considered only storing with a partial tank to save on stabilizer but read that the upper part of the tank could rust and cause fuel pump and filter problems.
Sea-foam is less than $7 for a 16 oz bottle at Walmart so it costs less than $28 to treat the gasoline for storage. Cheap insurance.

Right On Kirk !!!

[Rjpetr65]

I attended a seminar on Onan generators at the FL RV show which was awesome. Here are some tips:

1. Exercise your generator once per month if you are parked for several months at a time. That keeps the fuel in the carb from gumming it up, drys out moisture that accumulates in the windings of the generator, and keeps the seals and gaskets lubricated.

2. If you suspect a carb issue (typical prob is when the engine rpms speed up, then drop, then speed up, and drop...). Remove the air filter, hold choke open, spray some Sea Foam into the carb and let it soak for about 20 mins. Then reassemble and start it. This was per a Cummins engineer that’s been there 20 years so he knows his stuff.

3. When you exercise your generator once per month, make sure you put 50% load on it. Running it with a small load or no load won’t do any good.

4. Learn to read the error codes. If there is a prob, the switch will flash an error code. Look it up and see if you can find the prob yourself before brining it to a service center.

5 If the RV is going to be in storage for a long time, take the hose off the bottom of the carb and put the end in a small container, turn the screw (near the hose) to the left and drain the fuel from the carb. No fuel in the bowl=no gum up probs. Then put the hose back on and turn the screw back to its original position so the gen will be ready to start when you get the rig back on the road again. Always add a fuel stabilizer if the rig will be sitting for a while.

There’s a lot of talk about the oil level here and I agree, however some of the older generators (I have an 04 Sunseeker) will happily run with little or no oil until the engine seizes lol. My Onan 4000 is that way. Albeit I was TOLD that by the Cummins engineer and wouldn’t want to test it! Lol