Walbro WYA 46b adjustment

[JonCraig]

Hi all,

Working on a Poulan Pro backpack blower for my neighbor. PPBP30, model number BL30 711971.

It would stall out under throttle up. Bought the carb kit, K20 WYA. Cleaned carb in ultrasonic cleaner, then carb spray. Replaced pump & gasket, and metering diaphragm & gasket in correct order. Machine idles, but still dies under acceleration.

Setting the low screw is the biggest PITA I've ever encountered. Tiny plastic screw, back out until threads disengage, then in 10 turns. Problem is that I can't feel when threads disengage, and needle is so small it's near impossible to tell if I'm turning in, or if screwdriver is slipping.

Question 1) Any tips/tricks/pointers?

Question 2) Have a link to a replacement carb? This thing is so cheap I assume there's a $30 Chinese clone carb, but searching on fleabay wasn't fruitful.

Any help would be appreciated. Thank you.

[KE4AVB]

Jon,

The part number is 574590501 for carburetor. They are around $40 + shipping.

Like you for some reason I just don't have any luck rebuilding these rotary carbs. I think my problem is that the throttle valve assemblies are worn out and leaking air. This lists for about $15 so by the time you put it and a kit in along with your labor its better to just buy a new carburetor.

As for adjustment of the mixture all you can do set it for the best idle mix plus a little richer. Don't forget to pressure test the crankcase as a leaking gasket or seal can cause the same problems.

[JonCraig]

Thanks for the tip about the leaking rotary vane--that led me to my fix. You're going to laugh, but this worked. I took the old metering diaphragm, figuring it was tough enough to not get sucked into the strato port, and blocked the strato port completely where the outer housing meets the carb. Now the blower runs like a champ. I don't think it gets as high an RPM as it did previously, but that might be a trick of my ears (it's not my blower, after all).

I suspect the rotary valve has been leaking for a while, as there was some scoring on the piston. I have the mixture fattened up just a touch now to try & keep it from running that lovely "almost lean enough to melt but not quite yet" EPA nonsense.

My neighbor is happy that he's only out the cost of a carb kit, and not a full carb, and best of all I have this thing out of my garage now!

Thanks again for the help!

--JC