Moderator: drseti
Thanks Paul.. Guess dinosaurs like us should be accustomed to the spinning prop, we’ve hand propped enough airplanes.drseti wrote:That was the easy part for me, Don. Very common in the British sports car world, as well as with motorcycles. The only difference is, I never before had to deal with a spinning propeller when synchronizing carbs.snaproll wrote: - the dual carbs is what I have a difficult time with.
Going with the flow is probably a good idea... I haven't figured out much of the Rotax marketing yet. Rotax adapts a different automotive pump (larger spacer required) and still hasn't got it right. The new oil filter with the higher bypass pressure was another adaptation - I had the new one tested at a local calibration lab and it relieved at 14 PSI, had a second one tested and got 13 PSI. Finally switched to the Tempest AA825706, same bypass pressure, higher burst pressure, and can be safety wired. Thanks.. Dondrdehave wrote:1. My first "new" fuel pump did the same thing--it often ran above the upper pressure limit on climb-out and landings. This forced me to stop boosting with the electric, on take-off, at least.
2. But, eventually I got so disgusted with it, I took it off and reinstalled the old, original AC pump--and it continued to chug along perfectly and always within pressure bounds.
3. Then, that latest SB comes along and I reluctantly put another new pump on. Now, this one consistently runs too low on pressure on climb-out, forcing me to put "turn on electric pump" back into my take-off checklist.
I won't speculate further; I've just learned to "go with the flow" on Rotax mechanical fuel pumps, now....
Roger,roger lee wrote:I hate ghost issues, but sometimes they just work out.
Well, my new fuel pump gave low pressure on climb out for the third time since being installed 3 months ago. Does seem to be correlated with initial climb although that could be a coincidence. The pressure went from 4.5 on take-off roll to 2.8 psi at 3500'. Didn't wait for it to go lower and hit the aux pump which kept things in the 4.0+ range. Once stabilized at altitude, the fuel pressure was fine without the aux pump. I also did a 500 fpm climb from 3500' to 5500' without the aux pump and the pressure was fine. Checked the pump on the ground and found no leaks. I'm now in the camp of turning the pump on at take-off. Engine never missed a beat, though, without the aux pump.drdehave wrote:1. My first "new" fuel pump did the same thing--it often ran above the upper pressure limit on climb-out and landings. This forced me to stop boosting with the electric, on take-off, at least.
2. But, eventually I got so disgusted with it, I took it off and reinstalled the old, original AC pump--and it continued to chug along perfectly and always within pressure bounds.
3. Then, that latest SB comes along and I reluctantly put another new pump on. Now, this one consistently runs too low on pressure on climb-out, forcing me to put "turn on electric pump" back into my take-off checklist.
I won't speculate further; I've just learned to "go with the flow" on Rotax mechanical fuel pumps, now....
We have dismantled a BCP pump and know how it works.
It has an internal pressure regulator so the pump itself is limited to less than 0.4Bar.
It has triple diaphragms for improved safety.
The one way valves work sooo well I suspect it could cause slight pressure fluctuations, but as it is only filling up a float chamber this is not be a problem (bit like your toilet cistern). If you have a flow sensor that is too close to the pump or carbs it may be more susceptible to indication errors as result of the pressure fluctuations. Please see some technical information regarding flow sensor positioning from TL Electronics (this was prior to the BCP pump). http://www2.tl-elektronic.cz/instrum...e/AN-03_en.pdf http://www2.tl-elektronic.cz/instrum...e/AN-05_en.pdf
It has a strainer on the inlet side.
The vapour return orifice size should make no difference to the pressure (unless it is way too big that is).
The drain port is purely to drain any small amount of oil that can be seep past the oil seal on the shaft as it moves in and out. - incorrect positioning of the drain hose could slightly affect the pressure as it acts on the back of the pressure regulator.
The pressure limits for the 912 fuel system with a BCP pump are 0.15-0.5Bar.
Pressure fluctuations within the normal operating range as not considered to be a problem.
Low pressure for a short period is possible and allowed.
How are you getting over 7gph with a Rotax 912? Running at 6500rpm?snaproll wrote:To All,
Since I first reported the issue in January, my fuel pressure has been staying within operational limits. I did reset the fuel flow parameters to get rid of the "High Fuel Flow" alarm. The monitoring system was set to alarm at 7 GPM - I reset it to 7.2 GPM. Pressure stays between 3.4 and 4.8 PSI.
VR.. Don
