probably a dumb question but...

[suzysurvivor]

we have one of those monster Generac generators that runs on propane.   

Here's my question:  once it kicks on....does it just run and use propane at a consistent rate or do it use less propane if we use less watts?  Like if we only run the fridge and one light...or does it use the same amount at the same rate if we light up the whole house?

[Redman]

Pretty sure they run at a constant speed but fuel consumption may increase with the load. Burning more fuel to maintain speed most likely.

[Carl]

  Constant RPM but fuel use increases with power provision.

[IKN]

Think of it like your car. Fuel usage goes up if driving into a strong headwind, i.e more power required to maintain speed due to increased load from wind resistance.
Your generator also requires a certain amount of fuel just to run even if little or no load.
The engine also has a "Sweet Spot" as far as load. Above this point the amount of fuel required goes up more for the same increase in load.