Help! Generator shuts off while running A/C

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Help! Generator shuts off while running A/C

August 07, 2015, 10:42:35 pm

Yahoo Message Number: 154513

Set up: 2011 24fl, onan rv qg 4000 generator, dometic a/c w/heat pump, full tank of gas. Using Genturi exhaust chimney...always at a dogshow Ambient temperature mid 80s into 90s Symptoms: Generator quits after running 20 to 90 minutes with the A/C on, refrigerator on propane and all other apparent loads off. Near the end I can hear the A/C surging. Fault code 7 on A/C panel: no input power. No fault code on generator.
Note: A/C runs perfectly and for hours on 30amp shore power. Unfortunately I don't have that here.

Note: All maintenance and monthly runs done on generator.

Found oil too full....removed excess...no effect.
Tried starting generator, warming up, turning fan on first then turning cooling on...no effect.

Thoughts? Ideas?
This has been going on for 2 years. I don't dry camp much and I'll admit I was hoping it would resolve itself...ah magical thinking...

Lori Y 2011 24FL & Honda Ruckus

Re: Help! Generator shuts off while running A/C

Reply #1 – August 08, 2015, 12:33:09 am

Yahoo Message Number: 154514

This is the issue that I am having. I replaced the spark plug and air filter. I convinced myself that I needed a fuel pump or fuel filter (might be true). I am in the process of changing the fuel filter but although it is not that difficult a job it is much more involved than I anticipated. Larry made some suggestions that I wish I had followed from the start because it is a more logical process.

If your not handy with tools you want to have this job done by someone that does it on a regular basis. I have (maybe falsely) convinced myself that I have a fuel pump or fuel filter issue. At the bottom of the post is a link.

Good Luck.
John https://groups.yahoo.com/neo/groups/lifewithalazydazerv/conversations/topics/152251

Re: Help! Generator shuts off while running A/C

Reply #2 – August 08, 2015, 08:52:50 am

Yahoo Message Number: 154517

Lori, I'm going out on a limb, carrying a saw, and say that you most likely need to find a _good_ generator repair shop. My reasoning is as follows, and also makes a few assumptions, which I will address:
1) The fault code you refer to comes from what source? Several of us on this forum have the Progressive Industries EMS HW30C surge protector, which shows a fault code. IF, and that's a big IF (pun intended, sorry) that's what you have, then the fault is "Line Frequency HI" meaning above 69 Hz. In general, the generator's on-board circuitry should correct for this, OR shut the generator down to prevent damage to the generator or motorhome. So, I am making the assumption that you are reading the fault code from the PI surge protector.

2) In my limited experience, it sounds like the engine surging (vs. electrical surge) is caused by the generator portion trying to correct for an electrical problem. Think of it this way: if the generator is working normally, it spins a magnet at a certain rpm inside a coil of wire to produce the 110v at 60 Hz for the motorhome. The 110v is determined by the amount of wire the magnet is spinning in and the 60Hz is determined by the rpm the magnet is spinning. Lets also say that the rpm for 60Hz is 3600 rpm (I don't really know what it is, just an example). If the generator circuitry senses that the 110v is starting to drop, say to 100v, it will, in effect, step on the accelerator to speed up the generator. If the generator senses a lower frequency, say 55 Hz, it will speed up the generator to maintain the 60Hz. In other words, any load, like the A/C, when it starts up, will cause the voltage and frequency to drop. However, the generator tries to automatically correct for this and bring it's output back to 60Hz and 110v. That is, it will try to maintain the 3600 rpm. This is my 1st thought as the cause of your problem.

3) The engine surging can also be caused by fuel supply problems, like the infamous cracked fuel line problem, dirt in the fuel/ clogged fuel line filter, or carburetor problems. If it were one of these, I would suspect the carburetor 1st, just because _I think_ it is the most likely. Most carburetor problems are caused by the fuel clogging it up because the generator hasn't been run on a consistent basis.

4) There is also one other source for what you are seeing, which I experienced just a few months ago, and that is a failing, but not completely failed, ATS. ATS is automatic transfer switch and is also know as a LIne Generator switch. You can read more about it here:
http://nightskyranger.blogspot.com/ look for the (currently) 2nd entry for August 1, "Just returned from a trip to Texas", I think.
I was able to trouble shoot this generator problem mostly because I happened to have the right tools with me. Being a electrical engineer in a former life didn't hurt.

I hope this helps a little, and I hope you can get it fixed soon.
Ken

Re: Help! Generator shuts off while running A/C

Reply #3 – August 08, 2015, 12:39:57 pm

Yahoo Message Number: 154521

Just curious, but have you tried running WITHOUT the Genturi exhaust chimney? I can't believe that is good for the generator.

-Dave '06 MB, Indianapolis

Re: Help! Generator shuts off while running A/C

Reply #4 – August 08, 2015, 03:23:09 pm

Yahoo Message Number: 154524

I can't believe that is good for the generator.
--- Serious question: assuming the Gen-turi is properly connected (no leaks and no restricted exhaust flow), why would using the product not be "good" for the generator?

Joan

Re: Help! Generator shuts off while running A/C

Reply #5 – August 08, 2015, 03:56:06 pm

Yahoo Message Number: 154527

These are air cooled motors, similar to lawn mower motors. After an hour and a half under a near full load, the genset is going to get hot. Look first for spark plugs, points and mostly the mixture setting on the carburetor. If it is too lean (high altitude) it will loose power the hotter it gets until it can't pull the load and stops running.
You also should check to make sure nothing is blocking the air flow that cools the motor. Bent baffles or a damaged cooling fan could also cause problems.

Re: Help! Generator shuts off while running A/C

Reply #6 – August 08, 2015, 04:03:49 pm

Yahoo Message Number: 154529

Because of all the things you just asked. The exhaust flow is already restricted by the small pipe across the LD, adding any extra load cannot be good, plus the exhaust is likely quite cool by the time it leaves, I really don't know. I just asked if the OP had tried running the generator without, to rule it out, since it is not standard equipment.

-Dave '06 MB, Indianapolis

Re: Help! Generator shuts off while running A/C

Reply #7 – August 08, 2015, 06:28:51 pm

Yahoo Message Number: 154531

It should be easy to test the overheating theory and the effect of the Gen-Turi, using an inexpensive infrared thermometer.
Start and run, under load. After twenty minutes the temperature should stabilize.
Using an infrared thermometer, take temperature measurements of the head and the exhaust pipe, where it exits the genetrator.
When checking the head temp, open the side cover momentarily and replace immediately after the measurement is taken.
Let the generator continue running under load until it stalls or is close to stalling.
During this time, continue taking measurements every ten minutes and logging them.
Perform this test twice, with and without the Gen- Turi.
If overheating or an exhaust restriction is the cause, it should be obvious, with the temps continuously rising.
If the temps remand relatively stable, look for the cause elsewhere. The fuel system would the first place to explore. Another possible cause is an electronic control failure, one that happens when the component get hot. This has happen the several that I know of.
Imams have more than their fair share of problems.
Too bad Honda never built a 4000-watt RV generator.

Larry

Re: Help! Generator shuts off while running A/C

Reply #8 – August 11, 2015, 02:39:44 pm

Yahoo Message Number: 154612

Hi Larry, I assume you meant Honda in your post. have you ever seen these?
http://www.hondalawnparts.com/p/Honda-EV4010-EV6010-RV-Generator-Parts

Don't think they had a long run..

Ramon

Re: Help! Generator shuts off while running A/C

Reply #9 – June 11, 2016, 02:41:11 am

Update: Still bad &, yes, it fails the same way without the genturi chimney.
Replaced fuel filter, fuel pump good, cleaned exhaust system, replaced & gapped spark plug, replaced air filter, sprayed thoroughly with carburetor cleaner and tested with A/C while checking temperature as suggested by Larry. Ran 86 minutes with no temperature rise after initial warm up...and coughed once and died. Tried running with loosened gas cap in case vapor locking...no joy.

Thinking it's the electronics overheating and may also have the oil pressure sensor replaced.

Will keep updating until I figure this out.

Lori Y
2011 24FL

Re: Help! Generator shuts off while running A/C

Reply #10 – June 11, 2016, 12:03:08 pm

While I have not seen this problem on later model LDs, it sounds very much like the cracked fuel line issues that models built in the early 2000s have.
The generator has its own fuel line, coming from the gas tank. The rubber can age, harden and crack.
A cracked line can suck air, instead of fuel.
The symptoms are surging after the generator has run a while, many times ending with the generator stalling.
When the engine begins surging, you can usually hear the fuel pump clattering.
The problem increases as the fuel tank empties.
Changing the line from the tank can be a challenge, in some models the fuel tank must be dropped to access the line.
Fuel tank generator hose replacement | Flickr - Photo Sharing!

Larry

Re: Help! Generator shuts off while running A/C

Reply #11 – June 11, 2016, 11:18:02 pm

On my 96 with the Emerald Plus 4000, I had years of frustration trying to figure out my generator problems.
Finally found the right guy to help me and figured out that the voltage regulator was acting up.
It would run for an hour or so and then cut out like a fuel issue. I looked at every fuel line and filter and pump on the thing and all was fine.
The voltage regulator was failing and when it lost output voltage the generator would shut down.
These things have so many fail safes that sometimes diagnosing an issue is hard.
New voltage regulator and things are running well again after 3 years of not working at all.

Re: Help! Generator shuts off while running A/C

Reply #12 – June 12, 2016, 08:29:54 am

I deleted post. It covered ground that was already checked. Sorry.

Re: Help! Generator shuts off while running A/C

Reply #13 – July 26, 2016, 11:07:22 pm

The rest of the story...
I took the rig to the Onan shop today. They duplicated my problem, but also discovered the reason it was stalling out after about 90 minutes under load: serious over voltage...150v...causing it to automatically shut down.

Solution: new circuit board.

I'll be boondocking in some seriously warm temperatures this weekend for a dog event, so it'll get a real world workout. If I don't post a follow-up, it means it's cured.

Lori Y
2011 24FL
Carnation WA

Re: Help! Generator shuts off while running A/C

Reply #14 – July 29, 2016, 03:33:14 pm

Quote from: JCT - August 08, 2015, 03:23:09 pm

Yahoo Message Number: 154524
--- Serious question: assuming the Gen-turi is properly connected (no leaks and no restricted exhaust flow), why would using the product not be "good" for the generator?

As you add length and bends to an exhaust pipe you add back pressure. Back pressure increases the workload of the generator. IMHO we are asking our generators to do a yoemens job we shouldn't add more work to the system. By adding work to the system that the manufactures haven't factored in in the making of the system is a recipe for an early death of said system.

Re: Help! Generator shuts off while running A/C

Reply #15 – July 30, 2016, 04:26:04 pm

Good theory. Onan didn't indicate in any way that the Genturi caused it...and it did it without it. They did indicate they've seen a rash of fuel pump problems with the KYs. ...and some circuit board issues. No generator should fail with less than 80 hrs on it.

Lori Y
2011 24FL

Re: Help! Generator shuts off while running A/C

Reply #16 – July 30, 2016, 04:34:44 pm

Sorry...double post

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