Fuel Water Separator dry - not filling up

You talking about a Davco filter? It slowly fills up as the filter gets dirtier. It is working properly.

 

Yeah, that confused me too. I'm used to the Racor filter housings that need to be filled and purged of air.

 

With today's fuels, you never know what your pumping ie BIO vs pure diesel.... BIO is a thicker fuel and will tend to fill up your filter if too small of a micron filter is used. @ 7 micron, Bio fuel will run up the filter in no time, however if I use a 10 microns, the filter will allow fuel to flow through easier and give the appearance that there is no fuel, yet the engine runs normally. With a DAVCO System, Detroits call for 7 microns, ISX call for 25/50 microns and N14 call for 7/10 microns. In the winter months I always change to the a higher micron because fuel is thicker and your filter is more apt to clog. The problem is these lube places will install whatever filter they have on hand without consideration of what is required. http://www.davcotec.com/pdf/parts/3105.pdf

 

also on the davco filter in the fuel supply line into the filter there is a check valve that keeps the fuel from running back into the tank. sometimes the valve gets plugged with trash and can cause it to stick open and allow the fuel to run back into the tank.

 

I put a Davco on mine ... Took me a while to get used to the difference also but it's normal to see nothing till it gets dirty .. I was also used to seeing fuel midway up on my old style unit the Davco works a little different . Much better I might add

 

This is true. however, you would not notice this unless you unscrew the the cap or collar. air would have to escape before fuel would drain back. if there ever were trash in the back check, holding the ball & spring away from the seal, it would drain immed upon unsealing cap.

 

I have had my filter fill up within 20 miles from the loves bio diesel. I do not fuel there anymore cause of that. some times it would go 200 miles before filling up. went back to fuel stops, with no bio & back to normal intervals. I always have 3-4 spare filters at all times. if you get bio & it fills up the davco, & you have no spare, drain the filter to just above bottom collar & that will many times allow you to run a couple hundred miles, before you need to drain again.

 

Be sure your using the correct micron and if fuel is still not flowing like it should, like a 7 micron, step up to the next micron up, 10 micron. 3 microns is not enough to worry about and will allow bio to flow.