Flying Scotsman
Well Known Member
I have the following:
Lycoming IO-360-M1B w/ stock engine-driven fuel pump; Andair electric boost pump (latest generation).
I notice a slightly high fuel pressure the last few times when starting the engine the first time...normal fuel pressure has been 29-30 psi, but lately, for the first 3-5 minutes after start-up, I'm seeing around 33-34, which then drops back down to 28-30 for the duration. This is irrespective of which tank, or whether the boost pump is on or off, or the MAP/RPMs. By the time I get to the run-up area, it's down where it has been.
What could cause this? I know it's still way below the max allowed per Lycoming's Operator's Manual (45 psi), so everything is okay, but I'd like to understand it.
The only thing I can think of is temperature ???? It's been colder here lately, could that affect it (cold in the hangar, get outside and the fuel in the tanks warms up? That doesn't seem to make much sense to me, but what do I know?)...
TIA for any thoughts on this...
Steve
Lycoming IO-360-M1B w/ stock engine-driven fuel pump; Andair electric boost pump (latest generation).
I notice a slightly high fuel pressure the last few times when starting the engine the first time...normal fuel pressure has been 29-30 psi, but lately, for the first 3-5 minutes after start-up, I'm seeing around 33-34, which then drops back down to 28-30 for the duration. This is irrespective of which tank, or whether the boost pump is on or off, or the MAP/RPMs. By the time I get to the run-up area, it's down where it has been.
What could cause this? I know it's still way below the max allowed per Lycoming's Operator's Manual (45 psi), so everything is okay, but I'd like to understand it.
The only thing I can think of is temperature ???? It's been colder here lately, could that affect it (cold in the hangar, get outside and the fuel in the tanks warms up? That doesn't seem to make much sense to me, but what do I know?)...
TIA for any thoughts on this...
Steve