I have a 30cc homelite conversion. It has a walbro WA carb. One with the regular prime pump that would be on a weed eater. I cant seem to draw fuel when i am trying to prime it. Now this is the problem. BUT i also noticed (i dont know a lot about the gas engines yet) there is only one line going from the carb to the gas tank. Maybe i am wrong... but shouldnt there be a line from the carb to the engine as well??? Or how is the engine retrieving fuel???? If anyone can help it would be great!!!! Thanks.

Is there any fuel nipples not being used now? Can you post a photo. Capt,n

Is this a new carb? I have had many chain saws that "used to run great", that I had to replace the carb diaphrams in. The primer button is there just to get fuel into the pump chamber so it can be drawn through the carb body to the metering side. Every problem like yours that I have had, has been a leaky diaphram. There should only be one or two lines to the tank, but none to the engine. The pump in the carb gets its vacuum impulse through the carb body. Some full size ATV's have a vacuum pulse hose coming from the intake to the seperate fuel pump, but I have never seen this on a smaller engine. I hope I understood the question properly and was able to help.

I have an Echo GT with the same setup, these engines do not have a prime pump, only a blade type choke in the air cleaner. The best solution to this problem is to install a larger carb set up for a pump and add a return line. The carbs without a choke are a pain in the ---.

If the Walbro has a prime pump, it is normally (not on all models, see below) used to prime the carb with fuel only, so it is ready to rumble.
To get this done, the carb pump needs a fuel return line to the tank, which should be submerged at all times.
On some carb models the prime bulb not only serves the purpose of filling the carb with fuel, but also to prime the engine as well. I have read this in their patents, but do not know which carb model incorporates this idea. It would replace the choke valve or "wet thumb system".
Maybe RCign knows?

Not for sure..The one with the bulb can be left open and will just let fuel out when the carb is pumped full...It doesn't choke the carb, just fills it...The other, with no bulb, is a 1/16 tube sticking out from the side of the carb near the inlet diaphragm side..This one needs to be crimped or soldered shut for the carb to work...The carbs with the bulb mostly also have a choke plate, the others don't....I think those have a remote bulb and the choke that slides over the end of the carb....[8D]