i have a zenoah 40 cc gasser with walbro carb. i get the engine started easily with a squirt of gas in the carb. the problem is keeping it running. doesnt seem to be sucking gas up to the carb. any suggestions on hot to fix this or something else i should be looking at. it will run for 5-6 seconds then cut off.. i assume this is due to the lack of gas. if i need to clean the carb out what should i use and what do i take apart.. any suggestions would be appreciated..
thanks

Never heard of a Zenoah 40, but your problem is either old stiff diaphragms in the carb or a leak in the pulse from the crankcase to the carb..Check the small hole in the insulator block under the carb.....
The cover with one screw in the center is the pump side, the diaphragm goes against the carb with the gasket on top..The other side is the inlet needle side, 4 screws, gasket against the carb and the diaphragm on top...

well i messed with it a lil and i have it pumping fuel up the line now.. just need to go see if it runs correctly when i get a chance now.. looks like it should be ok

Is their a picture of this or something.
My Brison 2.4 was starting good for over 100 flights. Now, it is impossible to start without putting raw gas directly in the carb. I have gone to 3 flips and starting to 20 minutes of flipping and starting. When it starts, it runs great. Just hard to start!

Before ripping the carb apart,check the fuel line from clunk to engine CAREFULLY,looking for air leaks at all joints.If you use one of those fuel probe filler things,take it out of the system and throw it over the nearest fence,and use a fuel dot.
Make sure the vent line in your system is open.
Next check and clean the screen filter inside the carb.You wont beleive the amount of junk that will build up here and it doesnt take much to throw off a previously strong running engine.
Only when you have exhausted all the above should you have to start digging into the carb internally like the diaphragm.

Where exactly is the screen?
I don't think I can remove the inlet nipple.
What do I take off to get to the screen?

No reason to take out the inlet...The screen is under the pump side cover, one screw in the middle....