CARDFAN

My Feedback: (64)

Long story but I replaced the diaphram and check valve membrane on the WALBRO carb mounted to my Evolution 45cc gasser(reed valve). Now when I fuel it, the gas goes into the carb from the fueling line while also filling the tank. I use a 3-way "TEE" for fueling. Some goes to the tank also but mostly after filling the crankcase through the pressure vent to the carb. Pulled the carb and noticed the needle had a slight amount of "crap" on it(maybe the initial problem???) keeping the needle from seating so I cleaned it & the seat then reinstalled(needle/seat looked good, did not replace). Refueled and the same problem. The fuel goes immediately to the carb with no resistance at all. Almost like the diaphram isn't working at all or a check valve(?) isn't working correctly. Any thoughts.

w8ye

My Feedback: (16)

On the regulator or metering valve side of the carb where you are working, the gasket goes against the carb body and the diaphragm goes on top of the gasket and then the steel cover with the vent hole. If you put the diaphragm against the carb body, it will hold the needle open.

On the pump side of the carb, the diaphragm with the check valve flaps must be against the carb body. The gasket goes on top and then the pump cover.

speedracerntrixie

My Feedback: (29)

+1 Sounds like you nailed it. For one of those reasons, the meetering needle is stuck in the open position.

CARDFAN

My Feedback: (64)

That's the way I have it(both assemblies) and it checks against the old assemblies. Equally true, what is being said about the needle being open must be true so I exercised it. It would not close on a consistent basis; kept hanging open. Cleaned the bore where the needle goes and operation improved dramicaly. It always amazes me how little it takes to screw up one of these things and how it doesn't happen to often. Suppose I should change needle and seat but, then I have to worry about the setting, and I really do not want to go through THAT!! Tryout tomorrow and will post what happens.
Thx, Ed [&o]

CARDFAN

My Feedback: (64)

Before going to the field I fueled and once again it leaked into the crankcase!@#$%^%$#![:@] Opened the check valve side of the carb and noticed the membrane was OPEN over the fuel cavity(can't see the forest for the trees sometimes) along with the gasket. Unfortuneately, the proper membrane was the blue plastic film(used, I assume, for methonal fuels) but I used it anyway. Apparently the black one was for another model carb in the WT series of carbs(mine is a WT455). Fueled again and everything OK. Went to the field and started the engine with idle settings set at factory recommendations and idle was good but rich and high end was rich and died. Leaned it out(HEnd) twice(total of 1/2 turn) and it began to "sing" for like 15-20sec. then get erractic; would not deaccelerate without dieing. Leaned the Lend out and it helped a little but mid and low end suffered and would die at idle. Think I have a height problem with the needle fulcrum. I do apologize about the membrane error...just replaced with the same material not wanting to switch to the blue material and did not notice it was configured differently.