05' 9200i water separator problem

If it's a Davco with the glass on top then it's normal. When the level running is at the top of the label, then it's time to change.

 

There is a check valve in the intake side of the separator. Make sure it isn't stuck open. They tend to get trash in them. Remove the fuel line, unscrew the fitting and you will find a small spring and plastic ball. Also, bubbles in the fuel is NOT normal. You must find where it is sucking in air. Could be loose fitting, damaged fuel line, cracked separator housing, etc.

 

I have found the smaller oring for the top cap missing/split before to cause issues like this.

 

fuel SHOULD stay in the bulb when truck off or running. you are supposed to see the fuel, unless you just changed the filter & it has not filtered enough to get into sight. air can get in from top -o- ring or bottom -o- ring under big collar at base of dome. if the check valve is defective, unscrew the top cap off, if the fuel drains out the backcheck is defective in some way. if fuel level does not move, backckeck is o.k.

 

re reading your post. I BET there is something wrong in check valve. take loose the line,(on mine it is the huge nut) pull out the back check parts, careful not to lose the black ball or spring. most likely a piece of trash stuck in their. I had tiny piece of foil stuck in the ball of backcheck, no doubt from bottle of additive I put in, the davco drained out faster than I could pour in. if you have put any additives in the last couple months & perhaps part of the foil top came lose & got poured into the tanks, it would eventually work it's way & get sucked into the fuel & get lodged in the backcheck area.