Join Date: Oct 2012
Location: Silver City, NM
A Real Puzzle in Carburetor
I'm surprised and disappointed that there've been no replies to my original question. Oh well.
This morning I went out there with fresh eyes and viewpoint after stewing over it most of the night. I took several steps -
1) Removed fuel and vacuum lines from tank valve. Opened tank valve, and got nothing - as it should be. Then connected a separate piece of tubing to vacuum line at tank valve and sucked on it. Gas flowed readily.
2) Removed bottom bowl (float bowl ??) from carburetor, got down close with flashlight and with reading glasses on, moved the float up and down and could clearly see the needle rising and falling with movement of float.
3) Made sure carb was vertical, left bowl off, let float dangle, connected tubing to tank valve vacuum port and sucked on it. Gas poured readily thru the opening for the float valve.
4) While gas was pouring I moved the float up and down and when up, the gas would stop flowing. Did this several times and seemed as tho' the float rose pretty high before shutting off, but it did shut off. (I cut a sheet of soft plastic to make a funnel for the gas to run down and into a cut off gallon jug. I also kept a dry chemical fire extinguisher next to me)
5) Removed float and needle and checked needle tip for any marks or material and checked float for leakage. All looks fine and I was surprised because I expected to find the float needle stuck open or partially open.
6) Put it all back together, making sure o-rings, etc. were seated properly. I had read last night where a fella said an easy way to check float level was to connect a piece of clear tubing to the bottom drain port of float bowl and start the engine. Holding the clear tubing up beside the carb, gas would rise in the tube and you can see the level. Makes sense -I've done a similar thing with a garden hose to check for level foundations. I think he said it should be about 1/8" above where float bowl mounts on carburetor.
7) HERE'S THE KICKER - With the engine running.....THE FLOAT BOWL REMAINED EMPTY ! ! ! After waiting several minutes and watching all, still no gas in float bowl, so I took the end of the tube and gently sucked on it, then blew into it. Yup - that float bowl is most definitely empty. No gas at all in it.
8) To my little pea brain, seeing that made it obvious why I was having a problem. Give it choke and it opens the enrichment circuit and feeds gas to the engine from a different part of carb. Give it throttle and it gets air but no fuel and starves out.
9) All well and good, but how can that be ?? Gas flows readily from the needle area when needle and float is removed. Float and needle move freely when moved gently by hand. Gas pours out when float is down.
10) A thought just now occurred to me.....when I put the float bowl back on, it's conceivable that something could be catching and forcing the float up and shutting off the flow of gas.
I'm taking a pissed-off break right now and will go back out and fool with it in a bit.
Any ideas would be appreciated...............Lar.