Just fitted a bosch fuel pump, after a few minor problems with hoses blowing off, ug what a mess, but anyway, now it wont start....???? It cranks over, the plugs are dry, when the pump comes on I can feel the rubber pipe swell slightly, so there is pressure, and I can hear the return fuel coming through. The computer I am using sometimes takes a couple of seconds to fire if it has been sitting for a while, but it has never not started. I am real sure of the orientation of the lines, but I will double check, any other ideas??? I've just thought I may have swapped the lines on the underside of the plastic part that goes intothe tank..... hmm, might have to check.....

Make sure the polarity is not reversed, I'm sure you cant fit the plug on the other way but its worth a try... the motor will run backwards if the polarity is reversed.

Also you said the tube is swelling. Maybe there is a clog somewhere in the line.