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Topic: Generator Not Staying On When It's Over 90 °F (Read 1417 times) previous topic - next topic
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Generator Not Staying On When It's Over 90 °F
My generator (Onan Emerald Plus 4000) runs very well when it's not very hot. I just ran it for an hour a couple of days ago when it was about 75 °F, with the A/C on and set to maximum cooling (the compressor turned on and off several times while the generator was running).

However, when the temperature is 90 or 95 °F or higher, the generator first starts as usual, but then it shuts down after three or five minutes (even without any load) and will not start again until the temperature is much lower again.

As far as I can tell the generator has enough oil, and the oil on the stick looks clean and yellow. I changed the spark plug, and it didn't make a noticeable difference. I checked the air filter, and it looked nice and clean. That's pretty much all I can do myself.

I asked a repair shop owner who also works with RV generators and other engines if he had heard about this symptom - and he had not. He also had no specific idea what this might be pointing to.

Does this sound familiar to someone and possibly points to a certain problem?

Klaus
2001 26.5 Mid-Bath
Re: Generator Not Staying On When It's Over 90 °F
Reply #1 –
Two guesses.
First, it could be a fuel line leak that happens when the rubber fuel line gets hot and soft, allowing a crack to open up enough to suck in air instead of fuel. When the fuel line cools, the crack closes up.
I saw this in early 2000 LDs and it was (is) a common problem. There are two sections of rubber fuel line, one down at the generator's fuel inlet and another up on top of the fuel tank. The top rubber hose requires the fuel tank to be partially lowered or dropped. The process has been discussed here many times, search the archives for more information.

Second, a less common issue is an electrical problem that only shows up when the part in question gets hot. Seen in coils and electric ignition modules.

It's most likely the first guess.
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 Staying On When It's Over 90 °F
Reply #2 –
Thank you, Larry. I will look for these discussions and go from  there. Klaus
2001 26.5 Mid-Bath
Re: Generator Not Staying On When It's Over 90 °F
Reply #3 –
A friend was having a similar issue...  found a YouTube video about too much oil causing shutdown.  Her oil had recently been changed and was right at the full mark, not over.  It had run fine in cooler temps.  After checking and ruling out fuel issues, decided to remove some oil with an old syringe...  Got level down to about halfway between full and low marks.  Doesn't make any sense to me but lowering the oil level slightly seems to have fixed it. 
1995 26.5 Island Bed
Re: Generator Not Staying On When It's Over 90 °F
Reply #4 –
Our LD was doing the same when we bought it a couple of years ago. Thought it was the line from the gas tank but after changing it and the pump in the tank that was not the problem. Turns out it was the generator fuel pump. Ours would overheat after about 10 minutes and quit. I replaced it and have never had another issue. I was able to find a “green label) Onan pump on line but even the knock-offs may work as well.
Frank & Maryann
Re: Generator Not Staying On When It's Over 90 °F
Reply #5 –
Hi Frank; Thanks, or as Larry said "the affected part over heats and quits", could easily be the fuel pump itself. Or some other part too, associated with the electrical. Klaus,, with a 2001 likely has the same Onan Emerald Plus (noisy beast, but pretty reliable) that I have. Amazon lists fuel pumps in the $20-$40 range. Maybe made by the same Chinese company that makes them for Onan.  RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Generator Not Staying On When It's Over 90 °F
Reply #6 –
Quote from: Duoglide  - 
Our LD was doing the same when we bought it a couple of years ago. Thought it was the line from the gas tank but after changing it and the pump in the tank that was not the problem. Turns out it was the generator fuel pump. Ours would overheat after about 10 minutes and quit. I replaced it and have never had another issue. I was able to find a “green label) Onan pump on line but even the knock-offs may work as well.
I had the same problem with my Onan, and confirmed it was the pump and not a bad fuel line by putting a short fuel line on the pump and the other end in a gas can underneath the coach. Same symptom - stopping at high temperatures. Replacing the pump fixed the problem.
2005 Jayco 24SS
Re: Generator Not Staying On When It's Over 90 °F
Reply #7 –
Thanks for all replies!

I already bought air, oil, fuel filters, and a fuel pump. Since I assume it is easier to replace the fuel pump than the fuel lines, I will start with that.

Klaus
2001 26.5 Mid-Bath
Re: Generator Not Staying On When It's Over 90 °F
Reply #8 –
Quote from: Eric Greenwell  - 
I confirmed it was the pump and not a bad fuel line by putting a short fuel line on the pump and the other end in a gas can underneath the coach.


Testing this way is relatively easy and will determine if a leaking fuel line or a bad pump causes the generator to stop when hot.

Since the OP's rig is a 2001, it was built during the years when the fuel lines rotted prematurely. The rubber fuel line was old when it was installed.
Our 2003 LD's lower line was replaced within two years when it developed cracks, and the upper line lasted several more years before it started leaking.
 
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 Staying On When It's Over 90 °F
Reply #9 –
"...built during the years when the fuel lines rotted prematurely. The rubber fuel line was old when it was installed."

We can thank miserly Ed Newton for that! He was of the mind that you don't throw away material that's already paid for.
Many of us have had to replace both upper and lower gen fuel lines because of that. I replaced the line from the tank to the gennie with solid stainless.   ::)
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Generator Not Staying On When It's Over 90 °F
Reply #10 –
Quote from: Larry W  - 

................ The rubber fuel line was old when it was installed. ....................


That's interesting about the line being old when installed.  It was about 2004 was when MTBE started to be banned and ethanol started to become "the additive of choice" in the gasoline industry.  There were many cases of premature fuel line failures with ethanol as "ethanol resistant" hose wasn't always used until sometime after about 2004.  My Dad had an older car that developed fuel leaks around 2004-2005 when all the fuel had ethanol where he lived...  Hose that had been soft for years turned rock hard very quickly once he started using E10.  It was difficult for us to find ethanol resistant fuel hose in stores around that time, they still had the "old stuff". 

From that experience I would have guessed the generator fuel line failures for vehicle built pre-2004 or so were ethanol related and not age related. 
1995 26.5 Island Bed
Re: Generator Not Staying On When It's Over 90 °F
Reply #11 –
Hi Mark; MTBE  ( methyl tertiary butyl ether) started being used to oxygenate fuel to make it burn more completely back in 1979. Problems in about 1999 when my rig was made, with MTBE leaking from tanks into groundwater, caused a switch to ethanol in 2002-2003 (California).  Because it absorbed water, it caused rust problems in tanks, and affected older hoses in pre ethanol vehicles. Right now I have a vapor leak somewhere. Rats maybe! also. I keep resetting the MIL (check engine light in a '99 Ford just says "engine maintenance needed", but not a liquid leak, and the generator still runs. I'm suspecting the carbon cannister purge line. Got to get under there to inspect those lines.   RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Generator Not Staying On When It's Over 90 °F
Reply #12 –
Hi Ron, I hope you find your issue soon!  It can be maddening to fix issues like that.  I was just surprised to hear stated that the reason for premature generator hose failures was "old fuel line installed at the factory" when I assumed it was the "switch to ethanol as an additive". 

Thanks to the knowledge and information on this forum, one of the first things I did on my 95 was drop the tank and replace the little piece of generator connector hose... it wasn't leaking yet...  but it was in pretty bad shape... it did split during removal.  (Installed new fuel pump module at the same time)

This forum sure saved me from a big hassle down the road as you know the generator hose probably would have failed at the worst time!
1995 26.5 Island Bed
Re: Generator Not Staying On When It's Over 90 °F
Reply #13 –

I haven't done much about my generator issue, but I found now a mechanic who has been from a fellow RVer recommended and who has worked on many generators and is willing to try to fix it.

I have a couple of questions.

It's an Emerald Plus BFG 4000; the model number (on the sticker) is 4BGEFA26100P.

1) In case it's the fuel line, what kind of fuel line do I need to buy and how long does is need to be?

2) When anyway someone is working on the generator I'd like to get a full generator service as well. I bought already a couple of parts (fuel pump, fuel filter, spark plug, oil and oil filter, air filter), but I'm wondering whether I should also have a carburetor at hand and if this carburetor would be the right one:
Amazon.com: Partman Carburetor FIT for Onan 146-0455 Carburetor with Two... 

3) In my research here in the archives I did not find much detailed information. However, a while ago I found a post from about 2 or 3 years ago in which the poster said that he had the fuel line repaired by Buddy's Welding & RV in Flagstaff and paid $147 for it. I find that very inexpensive. Unfortunately I cannot find this post again. Does anyone know by chance who the poster was? Buddy installed my solar system and I'm coming through Flagstaff in about 4 weeks. I could try to make an appointment with Buddy if the mechanic that will look at it now cannot make the generator running well for an extended time.

Thanks for your replies!

Klaus

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2001 26.5 Mid-Bath
Re: Generator Not Staying On When It's Over 90 °F
Reply #14 –
Hi Klaus;  well you'd need two spark plugs because our old Onan Emerald are two cylinder engines.  Pertinent information for generators is how many hours it has been run.
    I don't use mine enough, and forgot that there is a winter/summer adjustment in addition to an altitude setting.
    Mine would run poorly set for winter at sea level, (where I live) when it was really warm at 7000' altitude.    RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
Re: Generator Not Staying On When It's Over 90 °F
Reply #15 –
Hi Klaus,
Is it this thread?

Generator fuel line, finally failed.
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: Generator Not Staying On When It's Over 90 °F
Reply #16 –
Buddy's is a good shop.
If you can get in they should be able to help with the fuel line.
If not, right next door is a generator shop that has also helped me in the past, Flagstaff Tool and Equipment repair.
I had an issue with the voltage regulator and they were able to test it to verify it was bad.
Replaced that with an updated one last year and my Emerald Plus has been running fine since.
I use my generator, it now has about 2500 hours on it and seems to be working well.
Jota
96 23.5 FL
Re: Generator Not Staying On When It's Over 90 °F
Reply #17 –
Thanks for your replies!

I have to say that I was first in disbelieve and then in a small shock when I read that the generator is a two cylinder engine, with of course two spark plugs. When looking at the installed generator you don't see a second spark plug, and when the generator is running you (at least I) also don't hear that there are two cylinders at work.

I have found a picture of a non-installed generator like mine where I can see the second spark plug cable. Now I'm wondering if generator has to get uninstalled to replace the rear spark plug. Is this really necessary or is there a way to get to the second spark plug while the alternator remains installed? (Or is it maybe not necessary to replace the spark plugs at all?)

What kind of fuel line do I need to buy?

Yes, Greg (or is it Victoria?), that's the thread that I meant. Thanks for finding it.

Klaus
2001 26.5 Mid-Bath
Re: Generator Not Staying On When It's Over 90 °F
Reply #18 –
Quote from: Jota  - 
... right next door is a generator shop that has also helped me in the past, Flagstaff Tool and Equipment Repair.

Great information. Thank you. They are indeed right next to Buddy's Welding & RV.
2001 26.5 Mid-Bath
Re: Generator Not Staying On When It's Over 90 °F
Reply #19 –
If you go to Buddy's to have the fuel line replaced, they will have what you need there.
Buddy's son, Rusty is very capable and will probably be the one working on it.
And they get to sell you something which is always better for them than you supplying things.
On my 23.5 model, it needed about 18 feet of fuel line, I think.

And I believe if you are a contortionist, you can get to the other spark plug without removing anything.
Jota
96 23.5 FL
Re: Generator Not Staying On When It's Over 90 °F
Reply #20 –
Quote from: Jota  - 
And I believe if you are a contortionist, you can get to the other spark plug without removing anything.

Too bad that I just retired from that job!
2001 26.5 Mid-Bath
Re: Generator Not Staying On When It's Over 90 °F
Reply #21 –
Wait, there are TWO sparkplugs?
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: Generator Not Staying On When It's Over 90 °F
Reply #22 –
Quote from: HiLola  - 
Wait, there are TWO sparkplugs?

The Emerald generator used in the older LDs has two cylinders. Your rig has the single-cylinder Onan Microquiet.
The Emeralds were a more durable (and noisy) generator, we found that with heavy use at work, they lasted twice as long as the Microquiets before needing rebuilding. Besides having two cylinders, the Emeralds run at 1800 RPMs, compared to the Microquiet's 3600 RPMs, one reason why the Emeralds last so much longer.

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 Staying On When It's Over 90 °F
Reply #24 –
Quote from: Klaus  - 
What kind of fuel line do I need to buy?

Forgot to answer this,
Our 2003 has a plastic 5/16" fuel line running from the fuel tank to the generator,  the last foot or so on each end has a rubber fuel hose used to make the connections.. Replace the old hoses with new 5/16" fuel hose.
Make sure the new hose is rated for fuel and not water or air.

I never changed the plugs on an Onan Emerald that was installed in an RV, The Emeralds at work were on light-plant trailers or runway closure trailers.
LED Portable Lighted Runway Closure Marker RCM-D L-893 - Halibrite

Partially dropping the generator may provide enough room to access the rear spark plug.

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