149 Starts, then stalls after 15 seconds

[bullockcm]

149 just started having an issue, had been running fine. Now it starts but stalls after 15 - 30 seconds. Acts like it is draining the float bowl but I have checked and there is fuel in the bowl. I have checked the carb/main jet which is clear of debris, made sure the fuel tank cap was venting, and made sure there is gas in the tank .

The fuel shutoff isn't sealing completely as I noticed a drip from the line while I had it disconnected from the carb. I can't think of a reason this would cause the stalling issue though. Any thoughts on possible causes for the stalling?

Regards,
Mitch

[West Valley G]

Mitch. What happens after it stalls? Can you start it right back up for another
little while and it dies? If you can give a little more info maybe it can
be narrowed down a bit.

Ken

[bullockcm]

Good point Ken. Does not seem to want to restart after the first cycle until setting for an extended period of time. Normally a few hours before I have been able to get back to it, so it probably doesn't really take that long. On an immediate restart attempt it will almost catch once with choke off and throttle wide open.

Truthfully despite the run time seeming to match running the float bowl empty with the fuel off it really seems to act more like it is flooded. I'm just finding it hard to believe flooding would be this consistent and repeatable without fouling the plug to the point it won't run at all. My next step is to check the plug today. Normally a few second job but for some reason with this particular engine the shrouds are tight around the plug and will need to be removed to access the plug.

[R Bedell]

I would suggest you checking the Ignition Coil.

[bullockcm]

I had considered the coil briefly Roland but never seen one heat up and fail this quickly, has always taken 15-30 minutes. Has always been repeatable though.

With old motorcycles the saying is at least 50% of carb problems are ignition related!

[darkminion_17]

May need a new condenser, fuel line clogged, screen in tank or fuel cap vent clogged.

[bullockcm]

Have a good strong spark, at least when tested in atmosphere. Fuel line is new, tank vent is clear, and flow is good as I drained the tank to address the leak from fuel shutoff. Old plug had a heavy coating of carbon/sooty deposits. Not surprisingly as I think the valve seals leak oil as there is some oil smoke on a cold start. New plug was dry though so the carb will come off again. I do have a "spare" carb from a 12hp which physically appears the same. I will check the internals to make sure I don't need to swap the "jet".

Really wondering if there isn't some needle/seat issue or maybe more likely getting debris that is plugging the jet. Will see once I get the carb back off.

Appreciate all the suggestions.

[bullockcm]

Was able to spend some time this evening in the shop. Spare carb was in decent shape upon inspection so I swapped carbs and the tractor runs reasonably well. Removed the float bowl from the original carb and there wasn't much gas in it. All things considered I believe the needle/seat area must be the issue. I'll disassemble soon, might just be junk in the fuel inlet. Bowl gasket is well worn so I think a carb rebuild is in order regardless.

Been away from wrenching on the Cub's for a few years. Seems I remember reading there are 2 different carbs which came on the 1X9 series tractors. Any recommendations for rebuild parts? New parts to use vs. avoid? I know in the motorcycle world a lot of the "new" brass carb parts can be inferior and only used if the originals are defective or badly worn. Any issues with the Cub rebuild kits?

I'll dig thru the forum for the carb info but this place seems pretty quiet these days so feel free to probably repeat yourself if so inclined

Edit**** Been reading the forum and the carbs I have are definitely of the adjustable variety with removeable jet so I guess I have the Carter/Kohler carbs? Any rebuild kit recommendations for this carb?