hi there to all, i have a weird situation with a jacobson lawnmower with a briggs n stratton motor when i rebuilt it i put in a new carb daiaphram and new o ring to thr part where the carb meets with to cross over tube, and tried to start it up , this was a pulse carb i think, and it didnt start i recleaned all the parts ,tank, sanded the top of the tank down to make sure it was smooth, cleaned the high speed needle put in a new o ring then reassembeled it , no start,i put in srater fliud , it ran straight away then went dead, then i put my hand over the opening where the air cleaner goes then pulled a couple of times it would run only if my hand covered 90% of the opening this opening is where the choke plate is that is linked by linkafe to the diaphram so i dis this ,i put duck tape on the opening making a small hole for the long screw that holds the air cleaner to the carb and another slit by it a 1 inch long cut in the tape, now where i pull the rope it starts up and runs great but i want to know why i need to cover most of the carb in this way, is there an air leak or what other problem exists please help and thanks for any help.:thumbsup::thumbsup::thumbsup:

Check the pick up tubes in the carburetor may be plugged

Please post the engine Model, type and code numbers usuall found on the engine shroud just above the sparkplug. Have a good one. Geo

I also forgot to mention that you should make sure the adjustment screw is turned out about 2 turns from seat, if you have it set too lean then this could be your problem.

ok i checked pick up tubes they look all right no crap to clog them up, but ill look at the high speed needle thatr may be the problem i think i post what i find

well it worked i turned out the needle 2 turns now it runs and stArts fine thanks guys.