ok if my memory serves me the pumps running head pressure is 6-7 psi warm. the advance solenoid pushes the head pressure to 9-10 psi (cold). that is your cold advance. the output return line has a shrader valve built in on the inside. its a very small opening. if the pump starts to generate debries from cracked seals or chipped pump rings then the valve becomes plugged and or restricted. if its being restricted it may leak down as it sits or over night. that's when you get the starts runs till it warms then dies and no cause can be found? whats takes place is the head pressure exceeded the 10psi max. it can't physically open the internal valves to let fuel out to the injectors at that point. also the white smoke constantly and won't go away? this is the restricted valves problem. I have seen the output valve removed and left that way to run with a fuel filter added between the injector return lines to prevent fuel junk going down stream to the injectors and plugging them to. it still starts and runs just no cold advance. the pump in the mean while is still deteriorating inside sending out derbies till it ceases to function.
on a side note; for bubbles on the output side of the pump. if the tank has a restriction so big as to prevent flow. the system cavitation is to the point its makes bubble like a vacuum chamber. so even if the system is brand new and has no leaks you can still get bubbles from a blocked fuel pick up in the tank.