Hi hope someone maybe able to help. Have a Classic 35s with the AQ148 engine. Just replaced coil and engine starts but won't rev up and then cuts out after about 15 seconds. Had the carb off and cleaned it out, poking the holes in jet etc. Made no difference. Didn't check if there any holes in bowl but though ?? Drained old fuel but still no better. Any ideas what I can do. I'm guessing it's a fuel supply issue, but could be wrong.
Remove the carb again and go through this procedure, installing a new kit number 631021B.
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.
BRILLIANT ?
Thank you so much for posting your reply. I'm on it this afternoon. Have noticed immediately there is no seal at the bottom of the float needle valve. I'll do everything you suggest and get back once I've completed the surgery.
Hi again, I mentioned that my carb had no float valve seal when I dismantled it, the actual valve has a red rubber tip on it. Is this some sort of mod that does away with the o ring seal you mentioned? The mower came to me with a bag of spares the previous owner had and in there is and old brass coloured valve and a black o ring with the recess in one side. This valve is actually shorter in length than the silver one with rubber tip. Confused now as to which one is correct?
You have a Tecumseh engine, with should us a solid needle valve, no viton tip, and an viton seat. From your description I would say someoe put the wrong one in.
All sorted ?
Thank you for your answers, all worked out perfect and with a bit of faffing about I got it running and cutting. Just needs a new bottom blade now ?
Many thanks for all your help.
Joey
Rivets have you ever heard of this one....a mate of mine has a 35s that has a very weird fault. Been using it as normal, runs, cuts and stops, put it's back in workshop and 2 days later the mower has leaked pretty much all its oil over the floor. Tops it up, uses it all ok but a few days later the oil is out again ! I haven't seen it but asked me to ask you if you have ever come across this or read similar.
