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Generator not running properly
Hi again, folks.

We still have the original generator and had it overhauled about 2 - 2 1/2 years ago because after a period of maybe a couple of hours, the gen would just stop.  After the overhaul, it would run for quite a few hrs, but would still stop on its own when we always had at least a half of tank of gas. It never stopped because we hit the 1/4 level in the tank.

We never pursued it since now, because when we travelled for any length of time, we stayed at KOAs. Now the gen will quit after maybe 20 minutes or so. I'm wondering if there is a fuel filter in between the main gas line and the generator that would explain the stopping if there is in fact a clogged fuel filter.  Looking back on the overhaul, the company (a factory rep for our Onan generator) would have overlooked that as a possibility, since they may well have removed the gen to work on it.  They ran it for 8\
 hours straight with no stoppages, or rough running. 

Any thoughts??
2006 27' MidBath
Re: Generator not running properly
Reply #1 –
Quote from: Robert O'Neil  - 
Hi again, folks.

We still have the original generator and had it overhauled about 2 - 2 1/2 years ago because after a period of maybe a couple of hours, the gen would just stop.  After the overhaul, it would run for quite a few hrs, but would still stop on its own when we always had at least a half of tank of gas. It never stopped because we hit the 1/4 level in the tank.

We never pursued it since now, because when we travelled for any length of time, we stayed at KOAs. Now the gen will quit after maybe 20 minutes or so. I'm wondering if there is a fuel filter in between the main gas line and the generator that would explain the stopping if there is in fact a clogged fuel filter.  Looking back on the overhaul, the company (a factory rep for our Onan generator) would have overlooked that as a possibility, since they may well have removed the gen to work on it.  They ran it for 8\
 hours straight with no stoppages, or rough running. 

Any thoughts??

What work was done during the “overhaul”. After three years I’m determined the Onan 4000 to be a finicky SOB.
It does indeed have a fuel filter but I would lean more towards your carb or fuel pump.
I have been meticulous with maintenance on mine. Annually I change the oil with Royal Purple SAE30 synthetic oil, new OEM air filter, fresh spark plug and even added a fuel shut off so no fuel stays in the carb.
It’s not too bad of a job to replace the fuel filter and you can do it from the fuel line inlet. Check YouTube. I would make sure you have an Onan brand carb and not a cheap Chinese knockoff like I found in mine. I would also check the fuel altitude adjustment on the front.
I just put a fresh spark plug, fresh oil, and fresh air filter in mine tonight. Ran like a top for an hour and then gives a slight occasional surge. I can’t figure it but with Onan charging close to 1k for repairs that may or may not do the trick, I’ll keep learning from YouTube on how to try and get it running perfect.
Only use Onan parts if you can. Make sure oil isn’t overfilled. I’ve heard it prefers 1.5 over 1.6 quarts.
Joe B.
2008 26ft  grey/white Rear Bath
Family of 5 hitting the open road as much as we can.
Re: Generator not running properly
Reply #2 –
"I'm wondering if there is a fuel filter in between the main gas line and the generator that would explain the stopping if there is in fact a clogged fuel filter."

Your 2006 LD vintage would lead me to think that what you are experiencing is a cracked and leaking 2" length of fuel hose at the top of the main fuel pump in the gas tank. This line feeds the generator. If the hose is cracked, as many of us have experienced, it will allow air in the fuel line, thereby starving the gennie!
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Generator not running properly
Reply #3 –
Quote from: Lazy Bones  - 
"I'm wondering if there is a fuel filter in between the main gas line and the generator that would explain the stopping if there is in fact a clogged fuel filter."

Your 2006 LD vintage would lead me to think that what you are experiencing is a cracked and leaking 2" length of fuel hose at the top of the main fuel pump in the gas tank. This line feeds the generator. If the hose is cracked, as many of us have experienced, it will allow air in the fuel line, thereby starving the gennie!

I recall reading this was improved in later years. Do you recall which year the change was made?
Joe B.
2008 26ft  grey/white Rear Bath
Family of 5 hitting the open road as much as we can.
Re: Generator not running properly
Reply #4 –
Quote from: brewersarcade  - 
I recall reading this was improved in later years. Do you recall which year the change was made?

No one can tell for sure when LD finished using their stash of old fuel line, and bought a new roll. Our 2003’s generator’s rubber fuel line never looked new, the lower piece started leaking within two years.
A 2006 LD could certainly have leaking fuel lines.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Generator not running properly
Reply #5 –
Simple test for fuel line issues would be to disconnect the factory fuel line where it enters the generator at the rear driver side of the generator box (at the fuel filter).

Buy a length of the appropriate sized fuel hose at the auto parts store (a few bucks) and run that hose from the generator to a fuel can. 

Run the generator off of the new fuel can for a good long time and see if you can recreate any issues.

My 2003 generator would have been described as finicky until I replaced the above mentioned short section of rotted fuel hose at the tank.   After that, it was wonderful.

I again had issues a few years later when some mice chewed a couple of small holes in the plastic fuel line that runs from the short section to the generator.  Much troubleshooting later, I found and fixed those holes.  Now all is well again.

A properly setup Onan 4000 should be a reliable workhorse.  They are designed to run for 30,000 hours. 

Rich
2003 MB
Re: Generator not running properly
Reply #6 –
How do you access the rubber fuel line that runs from the main gas tank down to the side of the generator to inspect and replace it? DIY job? I'm wondering if I should add a stainless steel line or if anyone else has done so.
Joe B.
2008 26ft  grey/white Rear Bath
Family of 5 hitting the open road as much as we can.
Re: Generator not running properly
Reply #7 –
Thanks, folks for your great suggestions - it gives us a lot to check out. Really appreciate it, and will post our findings when the problem gets solved. Hopefully soon. Thanks again!!
2006 27' MidBath
Re: Generator not running properly
Reply #8 –
Quote from: brewersarcade  - 
How do you access the rubber fuel line that runs from the main gas tank down to the side of the generator to inspect and replace it? DIY job? I'm wondering if I should add a stainless steel line or if anyone else has done so.
The critical one is the short length that connects the tank port to the plastic hose. It is accessed by dropping the tank - at least far enough to work its topside. Very heavy tank empty, and dangerous too if not.

Steve
2004 FL
2013 Honda Fit
Re: Generator not running properly
Reply #9 –
Quote from: brewersarcade  - 
How do you access the rubber fuel line that runs from the main gas tank down to the side of the generator to inspect and replace it? DIY job? I'm wondering if I should add a stainless steel line or if anyone else has done so.

It's on top of the fuel tank.  You can reach a lot of it if you remove the rear tires and have long arms, but it's not easy.

One trick I used was to gently blow air (with a pump, not your mouth!) into the fuel line while listening carefully.  If it's a closed system, you should only hear air bubbling into the fuel tank.  You can also experiment with light suction and listen/look for air flowing into the hose.  There is a level at which you should be able to pressurize the line but not enough that it sucks fuel out.  It the line doesn't hold that suction, there is a leak. 

There is a lot you can do if you are patient and creative.  If you can demonstrate that the generator runs fine off of an alternate fuel source, you know where to look to look for issues. 

Rich
2003 MB
Re: Generator not running properly
Reply #10 –
I followed the advice on here to drop the tank and replace the entire fuel line (this one is rubber for the full length). It was also advised to change the fuel pump in the tank. The mechanic told me that was not my problem after dropping the tank as the line would hold air pressure. Sure enough it would run for long periods on a cold day but about 20 minutes on warm days and shut down. I ended up replacing the fuel pump (&filter) myself on the generator and that solved my issues. Found instructions on utube from an Aussie chap that made it pretty simple to do.  I’m not sorry I changed the main pump or line as it’s preventive maintenance but the problem was not there.
Frank & Maryann
Re: Generator not running properly
Reply #11 –
"It was also advised to change the fuel pump in the tank."

The commonsensical answer here is: If you are going to the trouble of dropping the tank, what better time than to replace the fuel pump. That's Preventative Maintenance!
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Generator not running properly
Reply #12 –
I agree. Once the tank was down it would have been foolish on my part not to change the pump. I also replaced the chassis filter at that time. When I changed the generator pump I also replaced that fuel line. I still need to install a shutoff in that line as well. I’d rather do maintenance at home and not on the road.
Frank & Maryann
Re: Generator not running properly
Reply #13 –
Hi folks - Just a follow up on the gen problem. First, a huge thanks to all of the input we received. Great stuff. RE: our '06 Mid-bath.

Turned out it was the fuel pump after all.  All is okay now.

Happy travels to all.

Rober (Barry) O'Neil
2006 27' MidBath
Re: Generator not running properly
Reply #14 –
Just a follow up on my previous note - the folks that took care of the problem are C&D Power in Martinez, CA. They took care of it very nicely.

Thanks again.

Barry
2006 27' MidBath
Re: Generator not running properly
Reply #15 –
There have been several fuel pump failures lately on the forum and among friends. All the rigs are 15 years old or older.
I wonder if this is an age-related thing where some pieces of plastic or a diaphragm are decaying from age.
If you own an older rig, it may be a good idea to carry a spare pump and filter or change them now as a preventative if a reliable generator is a necessity for your camping style.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze