carb problem

[cuttoit]

I have a 10-14 yr old Murray 38515x92a riding mower 12 hp. I just replaced the shorted alternator. I replaced the armature/coil and spark plug. I removed and cleaned the carb and reinstalled. Added a new fuel filter with an inline fuel shut off manual ball valve. I installed a starter button to eliminate the not working starter solenoid or switch.
I have had problems with the gas flooding the carb and getting into the engine oil so I would remove the fuel line when I wasn't using the tractor. I also had problems occasionally that the engine under load would act like it was running short of fuel and I would have to go full choke to keep it running. If it quit it would usually start right back up but then again soon want to die under load again. I have had the carb off three times and it seemed to have all gas passages clear and open. I cleaned it and blew through all passages with compressed air and all seemed ok. Dang it I still have the dying under load in a short time. I can usually start it right back up but still acts like it isn't getting the gas. The float seems to be working correctly. I can't believe this so simple carb is giving me such a problem. I am ready to throw the dang carb away and get a new one.
Any help would be appreciated by someone that has had similar problem and found the solution.

 

[Rivets]

I suspect that the problem is a bad float needle and seat. Have you change them? This is a common problem. Here is a procedure I use.

Needle and seat replacement

Remove the carb, and then remove the float bowl. Check the float bowl jet (which is the bowl screw) and make sure the jets both horizontal and vertical are clean and open. Tip the carb upside down and remove the float pin and float with needle attached. Look in the float needle passage and you should see the red float seat at the bottom of the passage. This is where a #5 crotchet hook would come in handy as you need to remove this seat. If you have no hook, but compressed air, you can blow through the fuel inlet and try to pop the seat out. Put your thumb over the passage to prevent the seat from flying who knows where. No air or hook try bending a stiff paper clip to dig the seat out.

I would either give the carb a good 24 hour soaking or have it ultrasonically cleaned at this time.

With the seat out clean the passage way with carb cleaner. Now you must find a drill bit slightly smaller than the passage way, to be used to press in the new seat. Apply a very, very small amount of a very light lube to the new seat. 3-1 oil or lighter, to help seat it better. Carefully insert the new seat in the passage way with the rings on the seat down toward the carb body. Slowly and carefully force the seat down with the back end of the drill bit. Once it is seated, check to see that it did not flip and the rings are up. *Next check to make sure that the float does not have any liquid in it. *If it does, replace. *If everything looks correct, attach the new needle to the float and install with the float pin centered. It everything is correct, the float should seat level to the carb body, when looking at it upside down. If everything looks good reattach the float bowl, making sure that both the bowl gasket and the nut gasket seal properly. Reinstall on the engine and test unit. Remember to have patience and take your time. Good luck, but I don't think you'll need it.

PS: *On the side of some Tecumseh carbs you will find a plastic cover. *Under this cover will be an idle jet. *Remove it and check to see that the jet is open both horizontally and vertically. *You should be able to push the old float needle wire through the vertical opening.

 

[cuttoit]

I took the dang carb off again and bought two cans of carb cleaner. removed the float bowl and needle. It seems not much air was going through from the inlet hose to the float valve seat. Mine doesn't seem to have a removable float seat or at least I couldn't see one. I stuck a paper clip into the opening and seemed to have opened up and now air flows freely through it from the inlet hose. This was probably my problem all along. My bowl mounting bolt does not act as a jet as it has no holes in it. I removed the main jet orifice and poked a paper clip through all the holes and it seems to be clear open. With the float and needle installed the needle was seating off the air when closed and open it had good air movement. I put carb back together and reinstalled on engine.
I cranked it and it started up but dang it the engine quit running again. DANG IT! I removed the hose and opened the inline shut off valve and was barely getting any gas through the hose. I removed the hose and it somehow had a restriction in it. I blew through it and some gunk came out. I reinstalled the hose and now I can see the inline filter is filling up better.
Here I go again. Cranked it with full choke and it started up. I backed it down to half throttle after a minute and it stays running now. I actually mowed for an hour and it never even sputtered once.
Thanks for the help.

 

[DarolW]

Sorry, wrong topic.