720 Gas carburetor vent

[ChaterAl]

There is a JD 720 gas tractor on the family farm which is equipped with a carburetor vent. The carb vent is the round thing just to the right of fuel bowl. There is a rubber line which screws into the top of the vent and runs into the bottom of the fuel tank. This thing and the oil pressure set up have caused all sorts of issues over the years when the tractor ran in the field. Currently the tractor has not run for several years and while the fuel tank was drained when the tractor was put away, the tractor now starts, runs for several seconds and then dies. From past experience with the carb vent, I suspect the carb vent is plugged with dried gas residue and my next move is to clean the thing.

Has anyone simply did away with the vent and oil pressure sediment bowl and just put on a normal sediment bowl?

 

[craigco]

I have a 630 it has a pipe plug in where
the vent line comes out of the carb. The
line to the tank was just cut and folded
over. The oil pressure fuel bowl has been
replaced with a ball valve and an inline
filter for gravity feed. Been like this
for the 10 years I have had it.

 

[WTW]

The vent system was not only a vent but a preventive measure to prevent vapor locking on hot days.
Nothing wrong with vent or the hydraulic shut off as it protected engine in two ways. It shut fuel
tank flow off when engine was not running preventing gas from running through a carburetor needle
valve into crankcase and also was a oil pressure safety mechanism to shut fuel off in event oil
pressure was lost. Best advice is remove and reseal this very simple control valve and vent. If you
are not capable someone that has done it can rebuild it in less than 30 minutes. DW