I have a fass 150 thats a few months old. I just replaced filters and everything worked fine for the last 400 miles.
The problem is When i false start the truck my Fass will not build pressure. When I start the truck my fuel pressure comes to 15 psi. IT seems like the pump is getting air locked if the truck sits for more than a few hours and is hard starting.
I have two gauges and they both have the same reading.
During my tests I checked all of my connections electrical and hoses.
I had a code P1689 come up then went away. It only appeared once. and has not come back.
Does anyone have any ideas on why i can only build pressure when the truck is running?

 

Did you twist one of the filters to get fuel running out? that might help with your air bubble you are talking about. I had a similar issue when installing once I got my air separator filled with fuel it would start sending through the line.

 

I did crack the filters and still was having a problem getting fuel to the pump so i took the line off the injection pump to get the air out of the line. Than I loosely attached the line to the injection pump and re false started it again to make sure i did not have air in the line.