Genset Question

DennyH · 08-06-2013, 08:58 AM

On our new 3011DS I was finally able to start the generator and have it stay running. I understand that this is not unusual for a new gen. I have about an hour on it and when trying to start the AC it surges and then quits. It has done this 4 or 5 times. Any suggestions??? Nothing else is on, ie microwave.

Thanks

**bclemens** · 08-06-2013, 12:27 PM

If you're at altitude, then there is an adjustment that needs to be made. At sea level I wonder if it is a fuel pump issue...I've been seeing a lot of those lately.

DennyH · 08-06-2013, 01:17 PM

I am in Middle Tennessee so altitude is not much of an issue(700ft) I will investigate the fuel pump issue further. Thanks!!

lbrunning · 08-06-2013, 07:23 PM

read the manual and follow the break in instructions you might be putting to much load on to soon.

**bclemens** · 08-07-2013, 01:10 PM

I don't know. I'm in a 3010 here at the Goshen Rally. Brand new new from the plant...fired up the gen, turned on the air. Been working great for two days now. Although I have nothing else on at all.

DennyH · 08-07-2013, 05:56 PM

Thanks for the input, but I still am not able to start the AC. Even when I go from Lo Fan only to Hi then back to Lo the gen quits. Taking the MH to an authorized Cummins/Onan repair station next week.

HappyGuy · 08-11-2013, 05:33 PM

I'm wondering if there is a restriction in the exhaust causing the stall. Pulling the plugs on the exhaust used to clean out the spark arrestor would uncork things.

bgilly · 08-14-2013, 10:03 PM

I agree with bclemens on it being the fuel pump. Mine fizzled out doing exactly what you described at the dealer on the day of our orientation. The generator ran fine the week before when we touring the unit.

There is a problem Onan has with the fuel pumps on these gensets (according to some research I did). It took less than 15 minutes for the shop to replace my fuel pump but I am afraid that it may happen again. I've read that some folks have had them changed several times.

Bobby

DennyH · 08-15-2013, 09:13 AM

I took the MH to an Authorized Cummins/Onas repair center yesterday(fortunately only 20 minutes from my house) and the first thing the mechanic did was look at the fuel pump. He verified it was built between October 2012 and April 2013 and said he was replacing it. I will get the MH back on Monday and let everyone knows what he found.

Thanks for the input!!!

trwmodela · 08-16-2013, 01:40 PM

I wonder if there is a serial number range that applies to the Onan fuel pumps. Also, what replacement pump is being installed? Some have commented that their replacements failed.

DennyH · 08-16-2013, 03:08 PM

Just received a call from the Cummins/Onan service center- Fuel pump replaced with a newer model and all is well!!! A/C starts and runs just fine. I will pick it up on Monday and if I can get any serial #'s I will pass them along.

Denny

DennyH · 08-20-2013, 07:10 AM

I guess I spoke too soon!! When I got the MH back home the same problem persists!!!! The gen does run much smoother but the A/C will not run. As soon as I switch the A/C on the gen quits. The guys at the Onan repair center put a load bank on the generator to simulate the the load and it passed so it does not appear to be a generator problem. I guess I have a different problem. Hmmmmmm! Very disgusted!

Acableguy06 · 08-20-2013, 07:32 AM

It still sounds like a generator problem. Even if there was an issue with the a/c pulling to much amperage, it would trip a breaker before shutting the genny down.

bgilly · 08-20-2013, 08:11 AM

Quote:

Originally Posted by trwmodela

I wonder if there is a serial number range that applies to the Onan fuel pumps. Also, what replacement pump is being installed? Some have commented that their replacements failed.

Mine was OEM. I don't know that Onan has a full grasp of what "lot" is affected. Some units do fine, some don't.

HappyGuy · 08-20-2013, 08:34 AM

I know that a UPS in the computer world can often pass a simulated load test when the load is introduced gradually and fail when the same load is applied suddenly. I'm wondering if this is what is happening here. I know when I turn on my AC the lights brown out and the generator bogs down so I'm sure that the AC is pretty close to maxing out the surge capacity of our 4 kw Onan ultra quiet unit. Didn't have the same behavior from an older / louder Onan genset of the same rating. One thing I did do that helped smooth the operation of the generator and ease the strain from AC cut in was change the oil over to 5W30 synthetic in place of the 30W that came from the factory. The cost was minimal (10.00). The manual recommended the switch to get the broadest operating range and I noticed a difference in startup and load handling.

Another thing to try is to shut off everything, switch the fridge to gas, turn on the blower/AC fan, and then try the AC. If the genset handles the switch over then you are probably looking at a problem with the generators ability to handle sudden loads or possibly a bad / loose ground on the genset itself.

BarryD0706 · 08-20-2013, 08:55 AM

Quote:

Originally Posted by Acableguy06

It still sounds like a generator problem. Even if there was an issue with the a/c pulling to much amperage, it would trip a breaker before shutting the genny down.

That is not the commonly reported experience.

bgilly · 08-20-2013, 09:23 AM

Quote:

Originally Posted by DennyH

I guess I spoke too soon!! When I got the MH back home the same problem persists!!!! The gen does run much smoother but the A/C will not run. As soon as I switch the A/C on the gen quits. The guys at the Onan repair center put a load bank on the generator to simulate the the load and it passed so it does not appear to be a generator problem. I guess I have a different problem. Hmmmmmm! Very disgusted!

Have you tried the air conditioner on shore power? Check it on shore power and check the amperage. It should hover around 15 amps with fan on high and compressor running.
Dometic states generator size required for these units is 3500 watt. The Onan 4000 is plenty.
Might check the voltage output of the generator. A loadbank doesn't care much about voltage but that Dometic A/C will.

Bobby

Acableguy06 · 08-20-2013, 09:25 AM

Quote:

Originally Posted by BarryD0706

That is not the commonly reported experience.

Ok, are the newer Onans set up to shut down on overload then?

In my experience with most generators on overload, the breaker on the genny should open before engine stalls due to running out of power. Unless the generator is severely over rated or to large of a gen end is put on a small motor. If an over load is shutting down an engine under load this would not be good on the voltage regulator either. Unless this is a function in the generator to just shut down with an overload.

John McClain · 08-20-2013, 09:51 AM

Is their a fault light blinking on the Gen start switch ?

DennyH · 08-20-2013, 02:39 PM

Lets see... Everything, including the A/C works on shore power. The generator runs fine on fan, both hi and lo, Microwave, etc. Just quits when A/C compressor comes on.
Another question- Where is the converter/charger on the 3011?? My house batteries are dead and will not charge over 11.93 volts.

Thanks

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