Gourockian

Hi, you might be having the same problem that I had with my Craftsman trimmer just this morning, although it is a different model.  My fuel lines had perished, along with the primer bulb and when I removed them, I did not pay too much attention as to what went where.  By the way, Sears were no help as the primer bulb was "no longer available", but I found an identical one at  Lowes.   Mine's has two fuel lines attached to the bulb and I'm assuming your's does too.

After connecting it all up the way I thought it should be, I got the bubbles in the line but no gas to the carb.  Then it dawned on me that the lines were reversed.  The feed line from the tank (the one with the submerged filter) goes straight to the intake of the carb.  The line from the carb outlet goes to the longer of the two outlets on the bulb holder and the one on the shorter outlet goes back to the tank.  So what happens is that when you operate the bulb, fuel is sucked up from the tank, in through the carb and bulb, then back to the tank so that you have a complete circuit.  I had been trying to pump fuel through the carb from the bulb, instead of sucking it the other way.

I hope this helps your situation, but if not, the only other possibility I can think of is that you have some sort of air leak which is causing a loss of pressure.

Best of luck,

Alistair