Fass acting strange

pavetim

Member
Jan 10, 2011
299
5
18
Helping a friend hook his fass 95 to his lbz. I have done one before but this one has me stumped. Its hooked up right and when I pull the filter I get a nice steady flow. Strange part is when you let pump run and loosen stock filter head bleed port nothing comes out, you can even feel the pump is running but not pushing fuel. But when you tighten the bleed port you can fell the pump pushing fuel again. It's acting like it needs backpressure to pump. Truck stays and dies after 10 seconds. In lost.
 

gmc502

Member
Jan 16, 2011
463
12
18
have you tried sucking fuel thru the pump,then turn it on.I know its suppose to be self priming but maybe.are you sure the flow path is right,just throwing ideas out
 

pavetim

Member
Jan 10, 2011
299
5
18
Not yet, I had him hook up stock lines and bled it, truck runs. Ill have him try to use the flow thru design and see if truck runs. Not sure if it's correct but I pulled the filter and turned key on. Gets nice flow but it doesn't come out the center metal tube, it comes out on the outside ports. Is that normal or is it supposed to go thru center of filter and the out the outside holes?
 

pavetim

Member
Jan 10, 2011
299
5
18
Figured it out. He also installed a XPD fuel filter delete and we put the stock filter back on and runs like a champ. With the delete it must have been sucking air somewhere, the fuel pressure wasn't even following commanded pressure.
 

torqued2dmax

Member
Mar 26, 2017
646
1
18
Brookville, PA
The crap stays on the outside of the filter , just go to Fass ride and watch video ! There should have been no vacuum , maybe you didnt have it primed the hole way . Good luck !