Racor filter empties to half full - why?

[Montemar]

Racor filter sight glass shows the filter is half full. Yesterday it was full! This has repeated itself a few times.
I have replaced fuel pump and checked for leaks. I presume it is siphonimg back to the tank.
Has anyone else had this?

 

[julians]

There Will be an air leak somewhere in the fuel flow circuit

 

[burgundyben]

Seal on the lid?

 

[Portofino]

There’s a load of very good looking fake or is it fekked ? Racor filters about .It’s as mentioned the o ring seal (s) on either the lid or T handle which are duffers and leak .
They are so good visually and packaging , copy wise it’s hard for even dealers to see until they start to leak / never quite seal .

 

[Rangerman]

There is very little in a Racor 500 or 900, the ball (which floats) and red seal in the picture forms a non return valve and stops the fuel going back to the tank if the Racor is higher than the fuel level. The problem maybe a small bit of debris on the seal face, you can try and clean it or get a service kit and replace it. easy job.

 

[QBhoy]

If your engine is still running, you’d think you aren’t drawing air perhaps. It’s not perhaps a separation of fuel and water you’re looking at presumably?

 

[simonfraser]

hm, first time i replaced a fuel filter recently and that one was not full either
no spillage
should a 'good' filter overflow when it is being changed / unscrewed ?

 

[Plum]

hm, first time i replaced a fuel filter recently and that one was not full either
no spillage
should a 'good' filter overflow when it is being changed / unscrewed ?

The OP was referring to the transparent sediment bowl being half full. Are you referring to the same symptom are or the referring to the filter element bowl being half full when you remove the element?

 

[simonfraser]

ah, my filter had no bowl, full metal jacket

when i unscrewed it it was def not full and nothing overflowed
easy to poor out of it without spilling

 

[Montemar]

Many thanks for replies.
These are original fitment and the level drop is new.
I did not know about the ball and washer so will check them and also change the O ring between knob and top. I had suspected the latter though when filters replaced on March there had been no subsequent problem until now