J

JimWoo50

Well Known Member
I have tried various -6 fittings to attach the fuel pump hose to my carb MA-4spa and none of them would go in more than a third of a turn by hand before they stop. Should I put a wrench on it and apply force to it or is there something I'm missing here? Is there a specially threaded fitting for this?
 
Is it safe to assime you were using an AN fitting with a 1/4" pipe thread like an AN823-6 ??
 
Do not force the fittings!!!!! The fuel inlet and outlet on the fuel pump are not pipe thread! The fitting for this purpose has machine thread, uses an O- ring and has a washer and jam nut. You can find them in Van,s catalog.

Martin Sutter
building and flying RV's since 1988
EAA Technical Counselor
 
Sorry, not the carb but only the pump have machine thread fittings. Carb should pipe thread.

Martin Sutter
Building and flying RV's since 1988
EAA Technical Counselor
 
Carb fitting

It is possible that the carb threads are not pipe thread. My MA4SPA has straight threads. Just for fun remove the fuel fitting from the mechanical fuel pump and see if it threads in.

Matt
 
If you are referring to the part number 95-509 finger-screen inlet fitting for the carburetor, it uses a national pipe straight fuel thread (.250-18 NPSF). You often see an NPT fitting screwed into the finger inlet screen- this is not technically correct.
 
fuel pump

AN 833-6 fitting with AN924-6 nut. Straight thread on both ends of fitting. o ring under the nut, hold the fitting from rotating and tighten the nut to squeeze the o ring. Fittings are also available in straight AN832 and 45- AN837 There are other fitting options but the above has been used successfully on many Pipers. The carb fitting is a straight thread to accept the inlet screen, the screen in turn will accept a pipe thread fitting, AN822-6 would be one exaMPLE.
 
john.schwaner said:
If you are referring to the part number 95-509 finger-screen inlet fitting for the carburetor, it uses a national pipe straight fuel thread (.250-18 NPSF). You often see an NPT fitting screwed into the finger inlet screen- this is not technically correct.
Click to expand...

Where can one buy the NPSF fitting?
 
Technically correct: A NPTF attaches to a NPSF (Dryseal American Standard Fuel ). This provides a fuel tight seal without the use of a sealant. Used in fuel systems where a thread sealant might present a contamination hazard.

Typical Usage: NPT as the "Dryseal" concept never really worked.
 
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