Carb flooding/leaking

s219 · Mar 23, 2020

Due to two mild winters in a row and lower consumption of firewood, I didn't run my log splitter for over a year. I had run it dry and did annual maintenance before storing it in early 2019.

Yesterday I decided to split some wood from a maple that came down a few weeks ago. Got the splitter fueled up but before I could start the engine I noticed fuel dripping from the carb. My first thought was the carb float was stuck, since I have seen that happen before on stored equipment. I took off the bowl and the float appeared to be moving OK and didn't seem to have fuel inside it (say if the float had developed a crack). The bowl looked clean with no gum or varnish. Put everything back together.

I took off the spark plug and pulled the start cord a few times, which expelled a lot of fuel (and due to being a windy day, required a change of pants). Gave it 15-20 minutes to dry out and then started and ran the splitter just fine. But when I took a break later and dropped the engine to idle, it subsequently began dripping fuel again. Only when running at half throttle or higher would it not drip.

So I am coming back to maybe the float having a crack or leak in it that prevents it from floating up and shutting the fuel supply valve. Or maybe the supply valve needle/seat has some foreign object or gum that prevents it from closing. Any other suggestions?

This is a Kohler SH265 engine by the way.

oldnslo · Mar 23, 2020

Sounds like the float needle is not seating or sealing properly. Some carbs have either a rubber tip on the needle or rubber seat that cam be replaced, some are brass seats with steel needle. These are much harder to stop leaking.

farmeratheart · Mar 23, 2020

Since it runs, I would put it back together and start it. Spray some carb cleaner or sea foam in the air intake and see if something loosens up?

Roadworthy · Mar 23, 2020

Remove the float. Put it under a weight in a bowl of gasoline and leave it overnight. Take it out and shake it. If you hear liquid in it you have a leak. If not it's fine. Examine your needle. See if there's a worn or depressed ring where it has rested on the seat. That can cause a leak as it won't shut off the fuel. Depending on your engine a new carburetor may be in your future.

dstig1 · Mar 24, 2020

With how cheap many carbs are these days, it's rarely worth it to try and repair, except to keep you going in a pinch. Price out a new one and you may be surprised. I had one that was $12. Not worth my time to even try to fix it for that. But the advice above sounds on target as to the cause.

s219 · Mar 24, 2020

I will try to tear into it tomorrow since it will be raining most of the day and I won't be able to do much else. I can get a rebuild kit with new float and new inlet needle (plus the other usual stuff I don't need right now) for about $11. A whole new carb is $35. It would be loads easier to just swap in a new needle and float than to replace the carb.

jaxs · Mar 25, 2020

I strongly disagree with popular opinion about cheap replacement carbs being better than repairing original carb. If original is a Niki for instance,they are a pos so you may as well replace it with another pos than waste time trying to fix something that poorly built. Older oem carbs are well worth repairing and 10 times easier than China junk. The symptoms point to bad seal at needle-seat. Before buying a kit just to get the needle and seat,try this. Our new word for today is lapping. Apply a dab of 2k-3k grit abrasive paste on tip of needle then rotate it back and forth in seat for 10 secounds,reposition 1/2 turn and continue back and forth rotation. Withdraw and apply another dab after several secounds and repeat. Auto polish that claim's to have cleaner is suitable but there's others if you look around. Chances are it will now seal but ANY gravity fed and many pulsed systems benefit from an inline ball valve.

s219 · Mar 25, 2020

Was able to dig into the carb today. Saw no glaring clues. The float doesn't have a crack or leak, and floats OK. The needle had a little ring of crud around the middle of the rubber tip which cleaned off easily. It's possible that was the cause of fuel overflowing but I can't see that being a real major leak. The valve seat looked fine (see picture below).