No gas goes in the little rubber primer bulb - Mantis Tiller

Probably try ebay make model and part. or thefind.com
but might not be primer "bulb" diredtions should come with part.
Will it start with a little gas on the air cleaner? yes just a few drops.

You should have 2 to the tank, the one with filter coming from tank goes to nipple on right side of carb, the nipple on left side by primer bulb goes to primer bulb and other from primer bulb back to tank as return line, how it should work is when you push primer bulb it pulls fuel from tank through carb and back to tank on return line so watch in tank orleave one line out that you think is return line and see if gas comes out when you prime, but remember it goes through the carb first before it goes back to tank, had a pic but too big to put on site sorry, 2StrokeJim

Hi There, Check the primer bulb for tare or pin holes. Replace it. Check and clean carb jet it maybe plugged with debree. Also check for spark which you didn't say. Replace with correct plug.
Note; Do not use strong cleaners on rubber seals (O rings and gaskets) They dry up and crack.
If needed use a dabble of grease on seals

Who connected these hoses? the normal routing for a machine with a primer is like this, the fuel hose from the tank with the filter on the end goes to the carb fuel inlet nozzel ( not to the primer ) nearest to the pump cover ( cover on carb held with one screw ) the pipe from the metering side of the carb connects to the shorter nozzel on the primer bulb ( suction side ), the longer nozzel on the primer ( pressure side ) connects to the pipe going back to the tank, just remember the primer pulls fuel from the carb,into the bulb, and pushes it back into the tank, it is not actually a primer it is a purge. because it is connected this way it is impossible to flood the engine no matter how many times the bulb is pressed.
Let me know if it starts and runs.

Check the fuel filter for plugging. Check the fuel lines for decay or other damage. Inspect the primer pump carefully for any cracks or holes in the bulb part. The primer is supposed to pull fuel through the carburetor from the tank supply line and filter and return it to the tank. Hope this helps!

on weedeaters,chain saws. most are the same.
line with little filter in gas tank goes to carb. line out of carb to primer bulb
line from primer bulb to gas tank

There should not be a vent hose--it probably goes to a port on the primer bulb. Check the fuel filter for plugging and the condition of all fuel lines (they should be original rubber, not plastic replacements). Try priming the carburetor with the bulb pump--it should pull fuel into the bulb after several pushes. If nothing, check the condition of the primer bulb--it should be soft without cracks or holes.The primer is supposed to pull fuel from the tank's fuel filter, into the carburetor top section, pass into the lower section through the metering valve which is controlled by the diaphragm, then out to the input port of the primer and out the other primer port to return fuel to the tank. Go to: http://www.drystacked.com for an excellent 12 page article on theory and troubleshooting of Walbro carburetors. Hope this helps!

Here's a sketch that might help you. The primer bulb will keep fuel in it.

One line from the tank (that has a filter on the end in the tank) is the main supply to the carburetor. The other line in the tank has no filter and is the outlet side of the primer pump. There is also a line between the carburetor and the primer inlet side. The primer is supposed to **** fuel from the tank, through the carburetor and back to the tank. The main supply line is usually a little bigger than the primer pump lines. The tank should be vented through a separate screened hole or a vented tank cap.

This part is sold as an assembly Part# 530038874
Undo the screws holding the primer and note the fuel line location
as the new one will be identical.
Note the long and short tube connection under the primer bulb itself and the designated tube for each