A carburetor thing

RalphVa · Jul 8, 2018

Not sure this belongs here, but I could not figure where else to put it.

My JD walkbehind 14SB had to run with the choke on last time I used it. Went to start it yesterday, and it wouldn't keep going on choke. Only way to get it to run very long was some ether on the air cleaner. Took the idle screw out and blew the jetting hole out with the ether. Then wouldn't even fire with the ether. Gave up and let the wife finish up the mowing with the Honda walkbehind. She races around like a horse on a track with that thing wide open.

Today, figured I'd have to take the carb off. Before, I'd always staved off carb work with Sea Foam additive. Choked it and pulled the rope. Started right up. Shut off fuel and used up what was in the carb. Ran fine with the choke off. Last time, it was VERY reluctant to even get the blade going with it on choke.

Wondering why just doing the idle jet hole fixed it. Does the carb draw through the idle jet even on normal running?

Could be just soaking with the Sea Foam additive there fixed it up.

Ralph

skipmarcy · Jul 8, 2018

More than likely the idle circuit draws it's fuel from the cavity that the main jet is screwed/pressed into. A piece of contaminant could have been sucked up against the main jet, starving the chamber that the idle circuit draws from. Blowing into the idle circuit could very easily have dislodged the obstruction from the main jet temporarily solving the running problem. If it were mine I would drop the fuel bowl if it has one, or separate the airhorn from the fuel bowl section (if like a Marvel Schebler carb) and do a simple spraying with some choke spray and an air blowgun. Clean tools and a clean work area are necessary with carb work - a single grain of sand or whatever stuck on some needlenose pliers or a screwdriver can ruin the whole process. Good luck with it !!

ericm979 · Jul 8, 2018

The joke is "carburetor is the French word for 'leave it alone'". But they're not that complicated. Disassemble carefully, noting how the parts went together. I use spray carb cleaner to clean out the passages. Be careful as you can accidentally spray it in your eyes.

RalphVa · Jul 27, 2018

Still having troubles. Removed idle screw and blew it out with air. Put screw back in, backing off the same 2 1/4 turns it was set at. Started right up on choke and ran fine without the choke.

Ralph