Boost pump for Bing/3300?

[DCASonex]

The three important thing about installing fuel pressure sensors is same as buying real estate, location, location, location. At the low pressures of the Bing fuel system, the height at which the pressure is sensed relative to the bowl of the carb can make a significant difference. Try to install it as close to same height as possible. Also elevation of the pump makes a difference, if down low at bottom of cowl with collator, it will need to pump up to carb, but if located higher, more of its pressure appears at the carb. Also running with the 40105 pump, and some times see about 3.5 psi, have not had any problems of fuel flowing out, but do often see a bit in the balance tube, which runs uphill from bottom of carb to my intake, so is trapped there.

David A.

[Rick524]

Thanks David, my pressure sensor is mid span between the mech pump and carb. The pump is down near
the collator. Your reading tells me my sensor is about correct @ 2.9 psi. Im going to remove the bowl
and spray carb cleaner into the fuel input in hopes of clearing any debris from the needle valve/seat.
If that doesn't work, the carb will be removed for a closer look.

Rick

[Corby202]

If its of any help. Doug Smith is helpful on anything Jabiru.
https://jabiru.net.au/community/engines/

[Rick524]

Thanks Steve, David and Phil, I removed the bowl and sprayed carb cleaner while working the float up and down.
Then noticed one side of the float was lower than the other. I aligned them and adjusted the tab so the floats are level
when the float is just starting to push on the needle. Put the bowl on, turned on the pump and.....no leaks. Ran
it for 15 minutes without a drip. Pressure gauge showed 3.1 psi steady. Will start the engine next and see what the
mech pump shows then try both pumps at once. Curious to see what pressure will be with both.

Rick

[gcm52]

What is the function of a check valve with a aux fuel pump?

[DCASonex]

This is not likely, but if by chance your Bing carb did not come with the engine from Jabiru, Jabiru (or rather by the CAMit shop that assembled the engines) modified the needle seat for higher flow without reducing the needle and float's ability to hold pressure. If the inlet is simply bored out, it exposes more needle surface to the fuel pressure and thus the force from the float will be able to hold back less pressure.

David A.