Air in Fuel Line

[gar2376]

I have a JD F935 front mount diesel mower and am having a problem which I think is caused by air getting into my fuel line. It will run fine for awhile, but then it starts wanting to stall out. If I open up the bleeder screw and turn on the key so the fuel pump starts to pump, I can see little spurts of air bleeding out of the bleeder screw. After a few minutes straight fuel is coming out of the screw (no air) and I can tighten it back up and it will start up and run fine for a few minutes. Once I engage the PTO and hit thick grass, the process starts again. I thought maybe I had a pinhole in one of the fuel hoses. I have replaced all hoses and the problem still exists.

One thing I don't quite understand though, is that I don't believe I have a fuel/water separator. Is this optional?? My system appears to go from fuel tanks -->in-line fuel filter-->fuel pump-->fuel injection pump. I have a dual tank setup, and the attached pdf shows it should go fuel tanks -->fuel pump-->fuel/water separator-->fuel injection pump. On the single tank version of the attached pdf, the fuel/water separator looks just like the shape of an in-line fuel filter. According to the attached schematic, there is no in-line fuel filter before the fuel pump. Am I safe just taking this out? Do I need to get a fuel/water separator? My model does not have the water-in-fuel indicator, but I wouldn't think this would mean I don't need the separator.

Any help would be appreciated.

 

[kennyd]

It sounds like it may be a venting issue. Some have external vent lines and some have a vented fuel cap. Try loosening the cap when it starts to stall and/or listen for a big "whoooosh" of air entering the tank as the cap is loosened.