Fuel Pressure Gauge reads zero

[RLVoumard]

I back on the hunt for WHY at times my fuel pressure drops from normal to zero.

PA28 235
Lycoming O-540 B4B5 with 200 hours since MAJOR OH
replaced the engine pump thinking that might have had a bad one from OH - did nothing

This happens during CLIMB OUT usually above 6,000 feet does not matter what tank or qty in the tank. The gauge drops to below zero from mid range . I have a fuel flow that I can watch ( Ei FP5L ) it reads normal 18gph +/- ( climb at Full Power / 2500 RPM reading will vary with altitude) If the gauge were right , I would eventually starve the carb and run out of fuel , I don't and the FF remains steady. Flip on the electric pump and the reading climbs to mid range......turn for the electric pump falls to below zero

After climb , go to cruse and the fuel pressure return to normal. Engine pump only.

so

Its ONLY during a climb
Its at or above 6,000 ft - Home base is 160 MSL , I dont see this down low
I dont believe the gauge is actually reading fuel pressure that the carb is receiving
Go from Climb to cruse - the gauge recovers.

The PIC show the normal reading , and during climb..... I have seem the reading even LOWER than the pic

 

[Azpilot]

 

[RLVoumard]

 

[Azpilot]

 

[ycptechcom]

 

[RLVoumard]

 

[ycptechcom]

 

[RLVoumard]

 

[bill7]

 

[JChapp]