Our Winnebago has a 80 gal gas tank. The generator is suppose to run on the top 3rd of the gas tank, meaning that when full, I have approx 25 gal of gas to use for the generator. Question...about how long can I run the generator on this amount of gas...in other words, how many hours per gallon? Just wondering if generators are gas hogs or pretty efficient in general......THANKSBTW...it is an Onan generator....not sure at typing time what size exactly.

How big is the generator? Make and model?

I believe the genset will use gas from the top 2/3 to 3/4 of the gas tank-----------not the top 1/3.

Depends on the make and model of the generator and how heavily it is loaded.Basically impossible to answer.

Go here for the spec sheets for the Onan/Cummins RV generators. They include no load, half load and full load fuel consumption numbers.

kemer wrote:Our Winnebago has a 80 gal gas tank. The generator is suppose to run on the top 3rd of the gas tank, meaning that when full, I have approx 25 gal of gas to use for the generator. Question...about how long can I run the generator on this amount of gas...in other words, how many hours per gallon? Just wondering if generators are gas hogs or pretty efficient in general......THANKSBTW...it is an Onan generator....not sure at typing time what size exactly.Usually, it's the upper 3/4, but to answer your question, fuel consumption will vary with the load and one could safely say that at full load, never more than one gallon per hour. We average about 3/4 gallon per hour in the heat of the day, with our old 5.5kw relic, at my best estimate. Same size new, should be a little better and with a newer an much larger diesel unit, I would expect about the same as an old gas 5.5kw.

Generator duration | Good Sam Community

12 Replies

Dale_Traveling
Explorer II
Jun 27, 2016
You'll get about five days of continuous run time at half load but figure four days as a bit more conservative. If you conserve and only run during the heat of the day, morning and/or evening battery recharge you might be able to double the time.
JnJnKatiebug
Explorer
Jun 27, 2016
How level the rig is can make a huge difference. If fuel line is on the left and your rig is high on that side it can make a 2 or 3 inch difference from one side of the tank to the other. If you rig is low on the pickup side then that would be 2 to 3 inches the other way for a total of 4 to 6 inches difference.
turbojimmy
Explorer
Jun 27, 2016
TNGW1500SE wrote:
turbojimmy wrote:
Mine runs out of gas at about 3/4 tank but I think I might have a hole rotted in the pickup tube.

Not to hijack the thread but your generator might also have a weak fuel pump. See if it will pick up gas from a can.

Mine runs dry at 1/4 tank.

Thanks - it does suck gas out of a can. It seems to run out at random fuel levels for whatever reason. If I fill the tank up it will run fine again.
MrWizard
Moderator
Jun 27, 2016
appox 1/4 gal no load
1 gal per hour full load

1/2 ~ 3/4 gal per hr when using the roof top A/C
two A/c = 1 gal per hr
gswcgi
Explorer
Jun 27, 2016
Also remember that if you are above 5,000' you lose generator amp output as you increase altitude so your 5.5kw genny is capable of less power!!
TNGW1500SE
Explorer
Jun 27, 2016
turbojimmy wrote:
Mine runs out of gas at about 3/4 tank but I think I might have a hole rotted in the pickup tube.

Not to hijack the thread but your generator might also have a weak fuel pump. See if it will pick up gas from a can.

Mine runs dry at 1/4 tank.
turbojimmy
Explorer
Jun 27, 2016
tropical36 wrote:
Usually, it's the upper 3/4, but to answer your question, fuel consumption will vary with the load and one could safely say that at full load, never more than one gallon per hour. We average about 3/4 gallon per hour in the heat of the day, with our old 5.5kw relic, at my best estimate. Same size new, should be a little better and with a newer an much larger diesel unit, I would expect about the same as an old gas 5.5kw.

Mine runs out of gas at about 3/4 tank but I think I might have a hole rotted in the pickup tube. Fuel consumption is exactly as you described. Mine's a 6.5 Onan antique (32 years old).
tropical36
Explorer
Jun 27, 2016
kemer wrote:
Our Winnebago has a 80 gal gas tank. The generator is suppose to run on the top 3rd of the gas tank, meaning that when full, I have approx 25 gal of gas to use for the generator. Question...about how long can I run the generator on this amount of gas...in other words, how many hours per gallon? Just wondering if generators are gas hogs or pretty efficient in general......

THANKS

BTW...it is an Onan generator....not sure at typing time what size exactly.

Usually, it's the upper 3/4, but to answer your question, fuel consumption will vary with the load and one could safely say that at full load, never more than one gallon per hour. We average about 3/4 gallon per hour in the heat of the day, with our old 5.5kw relic, at my best estimate. Same size new, should be a little better and with a newer an much larger diesel unit, I would expect about the same as an old gas 5.5kw.
STBRetired
Explorer
Jun 27, 2016
Go here for the spec sheets for the Onan/Cummins RV generators. They include no load, half load and full load fuel consumption numbers.
KD4UPL
Explorer
Jun 27, 2016
Depends on the make and model of the generator and how heavily it is loaded.
Basically impossible to answer.