Gen fuel gph Check this

[Beatenbo]

For some time I have wanted to perform this little test. I have an Onan 10KW Quiet Diesel. Gen. It has an Isuzu 3 cyl instead of Kabota. It's a great running engine and after a year of running no complaints. The manual states fuel consumption at .50 gph at ½ load. Normally I am not at half load but at times according to my fill ups it's taking a lot.  When fuel was a dollar a gal no big deal but now close 3X it adds up.  (I don't buy the old comment, if your concerned about the fuel you probably can't afford the bus!) Don't like making the Arabs richer! I don't always get in a campgrounds and sometimes my gen runs 3-4 days solid. I can't check my bus or gen mileage because my gen is tapped into main tank. This is what I came up with. I use a clear plastic 2 ½ gal jug and measured 2 gals of fuel marking the 1 gal mark. Removed the supply and return lines and took 2 pieces of fuel line to the jug.  I stared gen turned on 3 roof air@ high cool and water heater plus usual little stuff like fridge, TV, satellite, surround sound ect. Probably as much as I would use on a hot summer day like today. Results...30 minutes...1/3 gal
1 hour...¾ gal...One gal...1 ½ hours. That includes cycling of A/C units and water heater. If I was using just 2 A/C and low cool at night I would probably be a ½ gph, average 12gal every 24 hours give or take. They are pretty close in their testing. Now I know for my self.

[JackConrad]

We have a separate tank for our generator.  Our old 6.5 KW Onan gasoline average .8 GPH based amount of fuel purchased and hourmeter. Our new PowerTech with the 3 cylinder Kubota has only ran 2 tankfuls of fuel, but so far .4 and .5 GPH per fill up. Last tank saw more AC time.  Jack

[Clarke Echols]

I don't know how genset diesels compare with the big Detroits, but a Series 50 or 60 DD uses about 0.3 to 0.35 gals/hr per horsepower.  I'm guessing the genset engines are in the same ballpark.

One HP is the same as 746 watts.  That means if the generator is about 75% efficient, you'll need about 1-1/3 HP per KW output.  If you're loaded at the full 10 KW, that's about 13-14 horsepower, and at 0.35 pounds of fuel per horsepower hour you're looking at about 4.9 lb/hour or 3/4 gallon per hour.

Diesel weighs about 7 pounds per gallon.

At 5 KW, you'd expect to burn close to 3/8 gallon per hour.  Given the figures you cited, I suspect the smaller diesels drink more fuel per HP-hr.  Whatever the fuel/hp-hr is, the method of calculation is still the same.

Hot dang, I think I ain't a newbie anymore! 
Clarke

[Beatenbo]

I find it pretty easy to figure the big ones. My MCIs have all seems to average about 7mpg. At 70 mph thats 10gph. If I figure how much feul to go some where I just use a rule of thumb. Hours driving X 10. about 90% of my trips are interstate, not much senic route. By the way thats how they rate aircraft mileage. gph.