Need some help on a fuel issue on my 55 chevy 327 engine. I have a Stewart Warner 240-A-12 electric fuel pump with 3/8" line to carb. The sending unit is bad and is a 5/16" so I purchase a new 3/8" sending unit to match the main line. I permatexed the sending unit in and ran new 3/8" line to in on electric fuel pump all ok. I turned pump on and it just sits there and pumps like mad and vibrates the back end of the car, so i let it run about 5 minutes or so and looked at carb see thru filter and just a little fuel is there. This unit used to pump pretty fast then slow down to norm as the fuel reached a good head pressure I assumed, now I am lost like the pump is air locked or not primed. I took filter out of bowl at bottom of pump and seems ok, so tried again, there is 1/4 tank of gas as well. At the top of pump is a threaded like weep hole and nut that should tighten what ever this does. Is this a bleed issue? Looking for a service sheet on this pump as well. What makes me mad is pump did work before I changed sending unit, well fuel gauge now does work so that is fixed. Well that is my problem and thanks for any advice.