On May 5, 1:39 pm, dpb wrote:
On May 5, 1:32 pm, brian wrote:

I have a Craftsman DYT 4000 tractor with a 21 HP Briggs V-Twin. There
is some kind of a problem with the engine. When the engine is running
with blades off it sputters and backfires. When blades are on it runs
smooth. I have replaced air filter, fuel lines, fuel filter, plugs
and cleaned out the Carb. There is no sign of water in the fuel.
Also there are times it will bout die when coming off a hill, then
blow a puff of black smoke. Could it be the fuel pump is going bad?
Any help is sure welcome.

Running too rich -- first choice is choke isn't opening fully so it's
running partially choked, therefore a rich mixture. If that's not so,
then there's a carb problem.

It does seem to run smoother with the choke on just a little, if its
not choked it sputters and backfires, if its fully choked it just
dies. I've took the carb off and everything look fine. (This is the
second carb i've put on it)