Generator issue documented with video

[EXTremist]

2013 3011DS generator issue: surges only when Dometic AC/Heat Pump compressor is used regardless of load. 3 videos showing voltage, freq, load and results.

VIDEO0037 on Vimeo
VIDEO0038 on Vimeo
VIDEO0039 on Vimeo

[EXTremist]

After watching my own videos again, the only difference I see the compressor is making is that it is dropping the output voltage of the generator by several volts.

Other facts: Generator has 155.5 hours on it, oil has been changed twice and the fuel pump was replaced under warranty as it would not start or run hardly at all when new.

[VinceU]

Originally Posted by EXTremist

2013 3011DS generator issue: surges only when Dometic AC/Heat Pump compressor is used regardless of load. 3 videos showing voltage, freq, load and results.

VIDEO0037 on Vimeo
VIDEO0038 on Vimeo
VIDEO0039 on Vimeo

Since the unit will deliver full load, can't be much wrong with engine or fuel system. The only difference I note is the A/C is "inductive load" where the water heater and space heater are resistive load. That may be a idea to provide to Dometic engineers or FR. Seems like somehow they are out of sync. causing way too much apparent power (false load).

[EXTremist]

Thanks! I will study up on the differences between the two. Been a long time but I do have an electrical degree.

[VinceU]

Originally Posted by EXTremist

Thanks! I will study up on the differences between the two. Been a long time but I do have an electrical degree.

I guess unsaid, would appear the heat pump is the problem, but just guessing.

[EXTremist]

The more I research at Flight Systems the more I lean towards a very slightly defective regulator. Spendy guess though.

[bclemens]

good video. Forwarded this on to Dometic.

[mud yapster]

Yes you should forward those videos to the gen guys, Dometics guys, and FR. Have you checked the capacitors on the roof A/C heatpump unit yet?

[bclemens]

EXTremist. Have you tested that just running the 15k A/C on high? is it just on heat pump low fan?

[EXTremist]

Any use of the compressor either AC or heat pump low or high will cause the generator to surge. As I stated in the video, the AC running in the heat will cause the gen to die completely. Thanks.

[bgilly]

I'm thinking generator - fuel aspiration or starving in the carburator/injector at near full load conditions. Have Onan place a load bank on the generator starting with resistive then trying reactive.

Also, note that altitude and extreme temps (85 degrees and above) affect the performance/output of the generator. The 4000 watt output rating is at 500 feet and 77 degrees F. according to my Onan rep.

Look at page 13 of the Onan manual for surging problems: http://www.cumminsonan.com/www/html/.../rv/F-1123.pdf

Dometic will tell you if it runs fine on shorepower - the problem lies with the generator. I've already been that route. In the end, they were right.

Bobby

[bclemens]

Yes, but why does the gen run fine pulling 27 amps of normal draw...but surge when there is 12 amps of compressor draw? The starving makes no sense if it is a load issue...when its starving at a smaller load.

I'm sending a unit over to Dometic to test...see if they can replicate the situation this week.

[TURBS]

Sounds to me " I'm no expert " that the governor on the gennie is "finicky" at the rpm when it starts to surge.

IMO there's an issue with the governor.

No issues light load
No issues heavy load

We had a generator that would do this only under certain load.
When I noticed at that "certain" rpm the governor spring vibrated so violently that it was making the governor "hunt" "surge".
We adjusted the governor and installed a new spring to find the issue dissappear.

My 2 pennies.

Turbs

[bgilly]

Originally Posted by bclemens

Yes, but why does the gen run fine pulling 27 amps of normal draw...but surge when there is 12 amps of compressor draw? The starving makes no sense if it is a load issue...when its starving at a smaller load.

It is a counter reaction of the generator/governor. Mine was doing the exact same thing - load banked the generator only and under reactive load bank the my generator surged. Cummins already replaced the fuel pump prior to the test. Cummins renewed the carburetor and it worked fine afterwards. Almost 15 hours on it since the work with a lot of it air conditioner load and has been fine.

Bobby

[EXTremist]

Thanks all...sounds like I need to take it to Cummins again for as load bank test rather than guessing at it.

[mud yapster]

Originally Posted by EXTremist

Thanks all...sounds like I need to take it to Cummins again for as load bank test rather than guessing at it.

Were you able to figure out what was wrong with it? This past weekend I boondocked to check all my stuff and the Cummins generator 5500 watt.
Saturday morning I fired up the genny to make coffee and to let it run to charge battery. I let it run for about 10 minutes to warm up and then I turned on the coffee maker, and then turned on the electric fireplace, the gen ran for about 5 minutes then surged and died. The only load was the coffee maker and electric fireplace. I checked everything and then went to restart it and it started back up, I then turned the coffee maker only back on and it ran for say 10 minutes and died again but it wasn't surging this time it just died. I looked things over again and restarted it and turned the coffee maker on again and it stayed running so I let it keep running for an hour to top off the battery. My gen has 7.4 hours on it now and on the wednesday before this I had run it for 2 hours with both A/C units on so I know it wasn't air in the fuel line and the gas in the tank is new. Well hope you got yours working now anyway. I'm going to run mine this evening under all different load configurations and see if it acts up anymore.

[mud yapster]

Found my genny problem, I thought my fuel pump quit. It would run for a few minutes and quit with load or without. Fuel pump wasnt pumping hardly any fuel so I removed it and tryied to blow thru the fuel line with my air compressor at 20 psi no luck it was clogged. I found where the fuel lines run alone the under side back to the fuel tank about 45' of fuel line. I took it loose at the tank and tried blowing threw it again with no luck. Traced line along rv back to genny and found the fuel line brackets supporting the lines were crushing the fuel line in 2 seperate places. I fixed those brakets and got good flow. Tested pump again and perfect fuel flow from pump. Hooked it all back up to genny and working perfect now. My Cummins onan 5500 only has 7.4 hrs on it and runs better now that it ever did in the last 7 hrs. I don't know what smashed the brackets holding the fuel line but its fixed now. Something you might look at to fix yours. Oh mine also surged from this.

[mud yapster]

Here is a pic of the brackets that run along the underbelly holding the fuel lines and 2 of them were crushed smashing off the fuel line. These bracket was the easier one to take a pic of but there are probable a dozen of these along the underbelly holding the fuel lines. I never could figure out what had smashed them I guess from the factory that way.