I cannot get my primer to pump fuel from tank although I took compressor and blowed back thru fuel line to tank and I heard bubbles in tank.

Sure way with fuel in tank and lines disconnected at the carburetor.

Connect the FILTERed line to either of the carb fuel ports. Leave other port disconnected. Pump the primer bulb (multiple times). If proper connection the primer bulb will fill and eject fuel out the unconnected carb port. If wrong, no fuel at bulb and air bubbles in the tank.

the line with the filter on the end goes to the pipe at the pump inlet and the other goes to the out let line back to the tank
the primers sucks fuel from the tank through the pump into the float diaphragm and back to the tank the action is to fill the pump and main jet system with fuel and to eliminate any air in the carby

Pull the spark plug wire to make sure the engine doesn't start. First check the line from the gas tank to the pump. Disconnect the fuel line from the gas tank at the fuel pump. Take off your gas tank fill cap and using light air pressure, blow into the line to see if you get bubbles in the gas tank. Canned air for cleaning computers or compressed air at a very low setting work well for this. Do not use high pressure so you don't burst the line or blow it off a connection that's not easy to get at. If no bubbles come up in the tank, check the line and pickup area of the tank. If the line is clear, reconnect everything. Disconnect the fuel line at the carburator. Holding the end of the fuel line in a small jar, turn the motor over. If the pump is OK it should shoot gas into the jar. If not the pump should be replaced. If it does check your float and needle valve in the carburator bowl.

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.

When you prime/puge your carburetor, make sure fuel (w/ no air) is moving from the fuel tank towards the body of the carb. Also, make sure that there is fuel/air bubbles leaving the primer bulb and going back towards the fuel tank...and that when you push the bulb down and release it, there is no fuel movement in either line. If fuel does move when letting up on the bulb, you either have the fuel lines reversed or, the check valves in the primer base assembly are not functioning. The primer/puge valve's funcion is to draw fresh fuel into the fuel pump side of the carb and to push old fuel/air from the metering chamber side of the carb back to the fuel tank. Here is proper fuel routing:
This is an ongoing issue for users, and rightfully so. Small diameter line out of fuel tank (has filter in-tank on end) connects 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. Years ago on 2-stroke trimmers, primers were not even used,...you choked the carb with a slide lever and gravity let fuel enter the carb from above...a few pulls, a "pop"...slide it off of choke and away you went.
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 the line is held in place with a nylon nipple connector that keeps the line from pulling out of the tank.

clogged fuel line or carberator. my weedeater did this at the first of the season. i took off both lines going to the gas tank and blew on each line separately while holding throttle open on carberator. i felt the clog go thru and put back together, poured a little gas in intake and it started right up and the primer worked right. good luck

What does your carburetor look like? Does it have a primer bulb? If so, look in the fuel tank and find the uptake filter, it's a cylindrical looking object connected to a fuel line inside the tank. Trace that line (an easy way I did this was to blow into the fuel lines myself and watch the cylinder, the line that makes it bubble out gas when blowing is the supply line) BE CAREFUL if you do this, you do not want to inadvertantly swallow gas!
Anyways, the line connected to the cylinder is the intake, the other is a return line and needs to be connected to the primer bulb port...from there it's gravy! Hope that helps you!

If you look closely there should be 2 holes in the fuel tank, also if you look inside the fuel tank there should be some remaining pieces of the fuel line and a fuel filter. If this has been sitting for any length of time you will also want to replace the fuel filter.

Now comes the fun... or a challenge

To start with you will need 2 sizes of fuel line ( go to a small engine repair shop) while you are replacing things you may want to buy a new primer bulb also.

to insert the fuel lines into the tank you will have to cut a tapered tail about 2 " long so that you can grab the fuel line with a needle nose and pull them through and out of the tank so that you can trim off the tapered tails. On one install the fuel filter and stick back into the tank, on the other trim the tapered tail off and pull the line back into the tank but leave about 1" sticking through the tank.

Now hook up you fuel lines to the carb and/ or primer bulb

Fill tank half full with fuel ... now test the installation if it doesn't pump fuel but instead you can hear it blow bubbles in the tank it is simple just reverse your lines on the carb / primer bulb

Retest if it works like it should you are ready to attempt to start it... good luck

ok If you have a Walbro WT series carb "without" a built on primer bulb here it is. First off if the fuel lines disintegrated you MUST disassemble it and clean it out. The MOST infintesimle speck of gas line trapped, can allow good prime and bad operation. OK? Don't be lazy on this. Just be delicate removing the flaps gasket and diaphram. ZAMA GND-12 Is the replacement Gasket and diaphram kit fot that carb. Use a cleaner, compressed air or blow good thru it. OK Now...Primer bulb, Carb, and Fuel tank, re connects: Smaller Diameter line comes from Gas tank (Connect filter screen to this in tank) to the short Straight brass carb connector. Primer bulb suction goes to the bent carb brass connector. If small line brings fuel "in" this other line sucks it back "Thru the primer bulb" and the blow side of the primer bulb sends it back to the fuel tank! So...Small Line brings fuel "TO/IN" carb thru short brass connect on carb. Other carb connect goes to bulb suction "IN", Then primer bulb "Pressure OUT" goes thru the larger tube "back to fuel tank". Trust me I know how frustrating a simple diagram is to find online fo this set up. And if you have a carb problem on top of the hook up uncertainty you got frustration. Not only was online help hard to find (Mfg...etc NFG at all!) My local repairshop in BBrook NJ could not tell me how!!! and thats no lie! Walbro has a "generic" carb diagram but no "hook up info" specifically. Poulan don't list it either. And these things routinly fall to pcs. all 3 of mine crumpled together on yr. 3 of use.

The larger of the 2 lines is the pick up/filter line - the smaller is the primer feed line that goes to the pressure bubble...The fittings are different sizes so it should be simple. To test it , with the hose out of the tank..press the primer bubble...it will blow air out of the line...