I'm trying to get an old weedeater/poulan 22" excalibur hedge trimmer running for my son. In the past someone has cut a fuel line going to primer bulb. I replaced that line and when I use the primer bulb, it builds pressure in the fuel tank rather than pump it to carb. I don't know if in the past someone has switched the fuel lines or if the carb has malfunctioned. if I spray a fuel mixture in the card the machine will fire.

There are 2 different set ups for fuel lines on these 2 stroke carburetors. One has a remote primer/purge bulb and the other has the primer/purge bulb on top of the carburetor. Here are instructions on how both kind work and how to service them.

The small diameter line out of fuel tank (has filter in-tank on end) connects directly to the side of the carburetor that has the fuel pump....that is the cover without the hole in it. Other larger diameter fuel line out of tank connects to the longer nipple on the external purge/primer bulb. The bulb "pulls" fresh fuel from the fuel tank to the carb and then out of the carb to itself, where it then "pushes" any air/old fuel back into the fuel tank. The remaining larger diameter fuel line in this setup goes from the metering chamber (has cover with writing on it and a vent-hole) side of the carburetor to the smaller nipple on the purge/primer bulb. Again, on the primer bulb, the longer nipple has a line going directly from it to the tank. This is the return line. The shorter nipple on the bub has a line from it going to the metering chamber side of the carb. If the purge/primer bulb is on top of the carb...small line from carb body to small hole in tank with filter. Larger diameter line goes from the bulb on the fuel pump side of the carb to the larger hole in the fuel tank where sometimes the line is held in place with a nylon nipple connector that keeps the line from pulling out of the tank. Otherwise, the line should enter the tank for about 1/2" or so If you have any more questions, please post back. I will see your comment and be glad to help you,

The primer bulb pulls fuel through the carb instead of pushing into. so yes when you prime it you tend to build pressure in the fuel tank. you should see fuel being pull to the carb through the other inlet fuel line. ( trick) take carb off and hook a piece of fuel line to both connectors and place in a small jar of fuel and see which blows out and which pulls in.. pulls in goes to your fuel filter in tank. blows out goes into tank about an inch or so for returning of fuel.if its a primer thats mounted seperate from carb same principal except your lines go from tank to carb. then to primer and then back to tank still pulling through the carb. hope this helps someone.