8N Fuel And Startng Problems - Ford 9N Service Manual

8N Fuel and Startng Problems

There was a fuel related starting problem when I first purchased my tractor. All of my
subsequent starting problems have also been fuel related. Either the fuel system plugs
from tank debris or fuel pours out of the air intake on the carb. The following float
adjustment procedure should be used to cure the flooding problem.
The fuel from the intake flooding problem is so common as to be the norm. The problem
is that the float valve is not closing. Either the float is hanging up on the side of the carb
housing or the needle valve is bad or has crud stuck in it holding it open.
This problem often starts in the gas tank where corrosion and crud builds up. Sometimes
it blocks the screen and you get no gas to the carb. A quick fix to this is to blow air
through the gas line and clear the blockage. If the crud gets to the needle valve and
blocks it open, you have the constant flooding problem. If the last guy tried to fix the
flooding problem and put a slight bend in the float, it hangs up and won't shut the valve.
Remove the carb and clean the outside of it with lacquer thinner. This will remove all of
the old varnish and grease. Soak it in a cut-off plastic jug and brush at the bad spots
every few minutes. When it's clean, remove the four screws that hold the carb body to
the throttle body. Discard the old gasket, remove the float and venturi (brass 'neck').
Pay attention to venturi orientation. Check the throttle shaft and choke shaft for
looseness. If they allow air to pass around the shaft, performance suffers and you
should replace the seals.
Completely disassemble the carb and soak it to remove deposits. I use a water-based
solvent that comes in a gallon can and has it's own parts basket. Available in auto parts
stores for about $10. If you are just replacing the float valve you may choose to bypass
this step.
Always replace the float valve needle and seat. It only costs a few bucks; why not? Use
the solid metal needle rather that the neoprene tipped type, it seals better. Check the
float ... sometimes it develops a leak and won't 'float'. Use compressed air to blow out
all passages.
Re-assemble the float valve and float without the venturi or new gasket. Hold the
throttle body up side down and observe the space between the float and the throttle
body. The surfaces should be parallel. Distance is important ... just over 1/4", less than
5/16". Now remove the float, carefully slip the venturi through the gasket and lay it in
place, then put the float back on. Screw the throttle body back onto the carb body.
Now you must check the float to make sure that it's not hanging up on the carb body. Do
this by holding the carb near your ear and quickly turning it over. You should hear a
"thunk" without any sound of metal scraping. Do this several times. Also, blow into the