Fuel pressure to Ca...
 
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Fuel pressure to Carburetor


bennisv
(@bennisv)
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Joined: 3 years ago
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My jabiru 2200 engine SN 2892 using Bing Type 64-3.  It is stated in manual that normal fuel pressure to Carb. is 0,75 to  3 PSI .
My question is how does Electrical Fuel pump if ON affect the fuel pressure to Carb. ?
My Electrical Fuel Pump is producing 4,5 PSI - measured directly from Pump.
Perhaps the Mechanical Fuel Pump is governing or providing the correct PSI pressure to Carb. even the
Electrical Fuel pump is ON .?

Another question: Is it recommended to have Electrical Fuel pump  ON during takeoff and landing ?

 

 


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bennisv
(@bennisv)
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Joined: 3 years ago
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Found out in jabiru manual that the maximum fuel pressure from Electric Fuel Pump may not be more than 4 PSI - if more then Carburetor flooding  could happen. My Electric Fuel Pump is giving 4,5 PSI so all questions in my previous post is answered.


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Doug Smith
(@doug-smith)
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Joined: 3 years ago
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Hi Bennisv,

4.5 may cause flooding, but on a 2200 it might be ok - they can be a little more tolerant of higher fuel pressure than the 3300, depending on a few details in your fuel system.  If it's causing problems it should be reasonably easy to tell - if the engine starts running rich when the pump is on, or if the carby starts leaking fuel out the bowl overflow.

And yes, the idea is to have the electric pump on during all critical modes of flight.  The idea is that if the mechanical pump fails you'll keep flying along happily on the electric pump, until a non-critical time, when there will be time to switch the electric pump back on and re-start the engine if there's an issue.

Regards,

Doug.


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bennisv
(@bennisv)
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Hi Doug

Thanks for your reply - You mention two symptoms of flooded carb.  1) The engine is running rich 2) Leaking problems from carb.
One of my friend who uses jabiru 2200 had issue relating using Electric Pump ON during approach. When he reduced power to idle
then engine stopped - he managed to start the engine again and landed - he soon suspected that the Carb flooding. After this issue he never use Electric Pump ON during takeoff and landing.  What concerns me (and my friend) if Carb gets flooded the engine could quit  during takeoff and landing with El. Pump ON). Perhaps this could be symptom number 3 ? .  Just speculating


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Doug Smith
(@doug-smith)
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There are a few things that can cause rough running or stoppage on final/landing... I've had engines stop on finals several times (I'm a slow learner) because the idle was set wrong (too low).

Because the RPM is low and the engine is not using much fuel, rich mixture on final approach can cause problems, and that should be looked at.  On take-off, because of the high RPM and high fuel use, it is less likely that there will be such an issue.

But yes, if turning the electric pump on causes the engine to quit then there is something not right.  The pressure from the pump can be too high, as you've found, or the carburettor can be adjusted incorrectly - sometimes just changing the float level a little can help issues like that.  The other thing to check is that the needle and seat are in good condition - if the seat is damaged of the needle degraded then it won't seal as well and can cause issues.

Regards,

Doug.


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e_hallsr
(@e_hallsr)
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hello doug  hope you might have a suggestion on why a 2200 a will not spool up with air cleaner connected but will spool up if  taken loose have changed filters and hoses but not taken the carb apart  it had run 50 hr with no problems the  an ap did conditional inspt. and some thing must have gone wrong any help will be great .thanks eddie


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bennisv
(@bennisv)
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Topic starter  

Thanks Doug

I will investigate this - I do not think I will do some Carb. adjustments this moment rather I will investigate or replace the El pump to get the correct pressure.


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