I picked up a 1990 Trail Boss 250 2x4 from a friend who thought i'd enjoy working on it more than he would. Right from the get go the thing would leave a puddle of gas in my workshop. He said he "washed" the carb but I thought the floats may have been overlooked or that the bowl valve was gummed. So I pulled the carb and bought a rebuild kit. I soaked the carb and chased the ports then replaced all of the jets and screws. I even made sure the float arms were adjusted to "parallel". Now this thing leaks more than ever. Even if I shut off the fuel at the tank all of the fuel will run out of the line through the carb and onto the floor. In addition, it's flowing way too much gas and fouling the plug. I noticed that the main needle was not the same number as the one that was in it but I don't have any way of knowing if the needle that was in it was original either. Once it's running it runs pretty well. It smokes a lot so I can tell it's pretty rich. I even pulled the carb off and cycled the engine to "pump" out some of the excess gas and the thing started right up for a few seconds The enricher plunger is new and adjusted correctly too. Any ideas?

 

Well the needle and seat are not closing to stop gas flow, closer look is needed. Something is keeping that open and it doesnt take much. The most tiny pc of dirt or damage to seat will cause a leak.

 

*UPDATE* I pulled the carb again and gave it an inspection. Still looks clean. I adjusted the float arms so it shuts off sooner. It still seems to leak whenever the fuel is turned on. Maybe not as much though. Also, the idle is really weak. Either it has to be turned up enough that the clutch is engaged or it's low enough that it just quits. I remembered that the gas I put in there is pretty old so I think i'll drain the tank and put some fresh non-oxy in it and see how that helps.

 

Okd fuel will always cause problems unless treated before hand. Even with treated fuel, 6 moths is about the limit. When diagnosing problems always best to use fresh fuel only!! If the carb is overflowing then the fuel shutoff needle and seat are not shutting off the fuel flow. New ones shoul have been included in your rebuild kit. If you did not use a quality rebuild kit, then that is your problem.
New kits have new seals and gaskets and gives you the nexessary adjustments for your carb.

 

Yeah, I installed the new ones from the kit. The kit seemed high quality enough. I got it from Dennis Kirk. I'll drain the tank tonight and put the fresh stuff in it. I put stabil in it last year but it was likely the first half of last year. Into the weed whacker and chainsaws it goes.

 

Was there a gasket under the needle seat? You could blow thru duel inlet and see if the needle and seat are closing with the carb off. Blow with your mouth, not a compressor.