atr42flyer

i have a homelite 33cc converted chain saw engine with a brand new carb. it will idle ok kinda high but will not run with the choke off. as soon as i open it to half it dies. this is after letting it warm up for 5 minutes. also i tried playing with the h and L needles and where is a good starting point. its a walbro carb wt 772b

bubbagates

My Feedback: (32)

Open both needles to 2 full turns and lean it from there but you may also have an air leak between the carb and engine

Safebet

My Feedback: (12)

Does it run good on full throttle with the choke open?

I would suggest you tear the carb down and replace the fuel pump diaphragm and the metering diaphragm. Check the needle lever to make sure it is
about level with the top of its slot. There is a small fine mesh screen on the fuel pump side. Remove the screen carefully and make sure the orfice underneath
is clean. This leads to the needle and seat. Go to your nearest lawnmower engine repair shop. You are going to need rebuild kit # K20WAT

TLH101

My Feedback: (90)

If the control arm on the carb butterfly has been changed, make sure the butterfly is in the correct position. The "screw head" should be facing the cylinder. If you look inside the carb, when installed, and see the screw head, it rotated the wrong way. remove the arm and rotate shaft 1/2 turn and reinstall the arm.

rctom

Are you sure the carb is getting a pressure pulse from the crankcase? This is necessary to drive the pump diaphragm.

Some carbs have a little hole in the base that must be channeled into the case, and some use an external line from the case to the carb.

If this pulse is not happening the engine can run on choke but not off because the pump is not working.

TF

ram3500-RCU

My Feedback: (221)

All good posts, but I agree with starting at the needle settings. I like to eliminate possible problems starting with the simplest of solutions. It sometimes saves me aggravation and time, and usually money.

If that doesn't work, (and I know you said a new carburetor) but this has been an indication of a clogged crap trap in the carb for me in the past. Also something easy to check and fix.

atr42flyer

thanks for the responses i put a brand new out of the box carb on it and it will idle fine a little on the high side but ok. there is no crankcase pressure feeding into the tank. and it will not run with the choke butterfly open. only closed will it idle if i open the throttle it does nothing actually wants to die.

Truckracer

My Feedback: (19)

Go back and read post #5 above. It sounds like your pump is not working!

Tired Old Man

My Feedback: (1)

And very possible the choke butterfly is installed backwards. New carbs sometimes have that problem.

ram3500-RCU

My Feedback: (221)

If it will only idle with the choke closed, it will never throttle up, open or otherwise. It is starving for fuel. Fuel should be dripping out of it, under those conditions, if the pump is working properly, the needles are set rich, your fuel system is clean and clear, and your not bleeding any air.

Flypaper 2

Take the carb off. There will be a hole in the gasket that matches the hole in the carb on the same side as the cover with the single big screw in it. The engine side will have a hole in the flange where the carb bolts on. Put the carb and gasket on to match the hole in the engine flange. A round about way of saying, the carb may be on up side down. Set both needle valves at 1 3/4 turns. This will be rich, but the engine will run.

Gord.