Can a JOHNSON CARBURATOR be so worn out that even if you rebuild it, It will not adjust.?

Question

I have a 1960 40hp johnson outboard. We rebuilt the carb and it is clean looks like new. Fuel pump is working, compression is 120 on top and 130 on bottom cylinder. Coils and point are new a well as good key and flywheel. Timing is right, fuel delivery is good, spark is strong..has new plugs, but can not tune it up....either she starts good but il not run, or will run good, but then hard to start.

Answer 1

yes they can be worn  out that bad,if the throttle shaft gets worn out or someone runs the idle s***w in to far the will not run right,if you ever overtightened the idle air s***w it ruins the carburetor,you can set it but it wont run right it will run real rich,that may be part of the problem with it.good luck.

Answer 2

b helpful to have link.

if it's butterfly type the seal(s) on the shaft get worn = air leak

slide type-bore wears out=air leak

next ques? how to fix-have worn parts bushed.

Answer 3

check for vacuum leak in fuel lines, there should be a constant vacuum or fuel in the lines only, any air infiltrations will s***w you up repeatedly, the motor will never start or run especially in older omc dual fuel lines, check the tank for any leaks, including the cap and gaskets, check for mud daubers in the vent lines, where screens are hidden from view,  mud will also s***w things up

Answer 4

It is possible for a carburetor to be worn out. I suspect you have a bad seal, probably a crankshaft seal. The first place fuel goes on a two stroke is into the crankcase and is then transferred to the combustion chamber by the piston moving downward. Bad seals on two strokes will drive you nuts with starting and tuning issues. This is discovered via a pressure test(actually pressure and vacuum to be thorough).Any competent repair shop can do this or buy a Mityvac and a manual and do it yourself. Do not exceed 6 psi