istrumit
Well Known Member
Hello -
On my fuel injected 540, I have noticed that my fuel flow in level flight increases significantly if I turn on the aux pump.
For instance, a few days ago, in stabilized level flight as 7500 feet burning 12 GPH. I wanted to see what the fuel pressure did if I turned on the aux pump.
When I turned on the aux, the pressure came up a couple of PSI as I would expect, but the fuel flow went from 12-ish to 15-16-ish.
Why is this ? I am assuming this is not making it to the engine for combustion (nothing about the engine measurements change).
Is there some sort of over-flow return line path in this case ? Meaning, the excess is returning to the tank but still getting measured as net flow by the transducer ?
On my fuel injected 540, I have noticed that my fuel flow in level flight increases significantly if I turn on the aux pump.
For instance, a few days ago, in stabilized level flight as 7500 feet burning 12 GPH. I wanted to see what the fuel pressure did if I turned on the aux pump.
When I turned on the aux, the pressure came up a couple of PSI as I would expect, but the fuel flow went from 12-ish to 15-16-ish.
Why is this ? I am assuming this is not making it to the engine for combustion (nothing about the engine measurements change).
Is there some sort of over-flow return line path in this case ? Meaning, the excess is returning to the tank but still getting measured as net flow by the transducer ?