Community Forums

khubbs · 08-29-2012, 05:49 PM

Hello, I have an onan dielsel generator in my 2007 Fleetwood Revolution and the generator idles fine however when I turn on one of the air conditioners, the generator screams out of control - it revs very very high. I tried the second air conditioning unit and it does the same thing. Any idea what this could be caused from? Thank you

trackman · 08-29-2012, 06:02 PM

If the air conditioner works when powered up the problem could be the carb adjustment screw or the fuel filter. If the adjustment screw is too far in it will surge. If the fuel filter is ready to be changed it will starve for fuel

rvjimmy · 08-29-2012, 06:36 PM

It's a diesel it has no carb. Maybe the govenor has a broken spring somewhere or the linkage needs adjustment.

Jim

calhyatt · 08-29-2012, 06:43 PM

Quote:

Originally Posted by khubbs

Hello, I have an onan dielsel generator in my 2007 Fleetwood Revolution and the generator idles fine however when I turn on one of the air conditioners, the generator screams out of control - it revs very very high. I tried the second air conditioning unit and it does the same thing. Any idea what this could be caused from? Thank you

Is it a quiet diesel with the type of generator that runs at different speeds according to load ? If so, I suspect the control board has a fault. Careful with that one. You can fry all your stuff if it runs away. If it is a constant speed generator usually 1800 rpm then the governor is not responding to the increased load, also a dangerous one if the genset runs away. High cycles and voltage... Good luck. Seeya on the road.

dennis45 · 08-29-2012, 07:28 PM

Quote:

Originally Posted by calhyatt

Is it a quiet diesel with the type of generator that runs at different speeds according to load ? If so, I suspect the control board has a fault. Careful with that one. You can fry all your stuff if it runs away. If it is a constant speed generator usually 1800 rpm then the governor is not responding to the increased load, also a dangerous one if the genset runs away. High cycles and voltage... Good luck. Seeya on the road.

Different RPM's for different loads? Never heard of that one.
Generators run at 1800 RPM to produce 60 Hz. (1500 RPM for 50 Hz in Europe)
When the load is increased (like turning on another appliance such as the AC) the governor allows more fuel/air to enter the engine (no mater if it is Diesel or Gas) and produce more Horsepower and still maintaining 1800 RPM, 60 Hz at that given load. Turn on another appliance, and the governor allows still more air and fuel to accomodate the higher load and maintain 60 Hz. This continues until the load exceeds the rating of the generator (7 KW for example) and then the engine will slow down because it is overloaded and cannot produce enough HP to handle the load.
If the engine speeds up when you apply load, you have a governor problem and whether it is a mechanical or electronic governor, it needs some TLC by someone who knows what they are doing. Cummins dealer would be my first choice unless you know of an independant that is qualified and recomended.

crah · 08-29-2012, 07:38 PM

Quote:

Originally Posted by dennis45

Different RPM's for different loads? Never heard of that one.
Generators run at 1800 RPM to produce 60 Hz. (1500 RPM for 50 Hz in Europe)
When the load is increased (like turning on another appliance such as the AC) the governor allows more fuel/air to enter the engine (no mater if it is Diesel or Gas) and produce more Horsepower and still maintaining 1800 RPM, 60 Hz at that given load. Turn on another appliance, and the governor allows still more air and fuel to accomodate the higher load and maintain 60 Hz. This continues until the load exceeds the rating of the generator (7 KW for example) and then the engine will slow down because it is overloaded and cannot produce enough HP to handle the load.
If the engine speeds up when you apply load, you have a governor problem and whether it is a mechanical or electronic governor, it needs some TLC by someone who knows what they are doing. Cummins dealer would be my first choice unless you know of an independant that is qualified and recomended.

Dennis that doesn't sound right. These onan quiet diesel generators are the inverter type and they do speed up and slow down based on load.

Unless I'm missing something I'm pretty sure that's how they work. I heard that there are some power tech and other diesel generators that run at a constant rpm.

calhyatt · 08-29-2012, 07:47 PM

I own a Powertech and it is a constant speed (1800) rpm generator. I am quite sure their are inverter type gen sets that vary speed according to load. I spoke about both in my response to this threads author in order to help him understand the possible causes of his apparant run away condition.

calhyatt · 08-29-2012, 07:59 PM

Quote:

Originally Posted by dennis45

Different RPM's for different loads? Never heard of that one.
Generators run at 1800 RPM to produce 60 Hz. (1500 RPM for 50 Hz in Europe)
When the load is increased (like turning on another appliance such as the AC) the governor allows more fuel/air to enter the engine (no mater if it is Diesel or Gas) and produce more Horsepower and still maintaining 1800 RPM, 60 Hz at that given load. Turn on another appliance, and the governor allows still more air and fuel to accomodate the higher load and maintain 60 Hz. This continues until the load exceeds the rating of the generator (7 KW for example) and then the engine will slow down because it is overloaded and cannot produce enough HP to handle the load.
If the engine speeds up when you apply load, you have a governor problem and whether it is a mechanical or electronic governor, it needs some TLC by someone who knows what they are doing. Cummins dealer would be my first choice unless you know of an independant that is qualified and recomended.

Take a look at the Onan Quiet diesel specs and you will see variable speed diesels. 8.0 KW 6.0 KW RV models.

I too have a constant speed (1800) rmp Powertech but I think the author of this thread may have on of the hybrid inverter type diesels.

Take care sir.

dennis45 · 08-29-2012, 08:09 PM

Quote:

Originally Posted by dennis45

Different RPM's for different loads? Never heard of that one.
Generators run at 1800 RPM to produce 60 Hz. (1500 RPM for 50 Hz in Europe)
When the load is increased (like turning on another appliance such as the AC) the governor allows more fuel/air to enter the engine (no mater if it is Diesel or Gas) and produce more Horsepower and still maintaining 1800 RPM, 60 Hz at that given load. Turn on another appliance, and the governor allows still more air and fuel to accomodate the higher load and maintain 60 Hz. This continues until the load exceeds the rating of the generator (7 KW for example) and then the engine will slow down because it is overloaded and cannot produce enough HP to handle the load.
If the engine speeds up when you apply load, you have a governor problem and whether it is a mechanical or electronic governor, it needs some TLC by someone who knows what they are doing. Cummins dealer would be my first choice unless you know of an independant that is qualified and recomended.

My sincere appologies. That's what I get for not paying attention.

http://www.cumminsonan.com/www/html/...ets/a-1408.pdf

My statement about a "Qualified Tech" is still valid. I have serviced many generators from 2KW to 1500KW and if I ran across this one I think I would respectfully decline until I did my homework.