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C21ZMR Gas Cap Vent

882 views 1 reply 1 participant last post by  JOG 
#1 ·
The mower has started squirting fuel from the vent in a small stream about 6-8" high. In the past the vent might occasionally drip fuel while mowing the side of a steep hill, but this is much more pronounced - almost like the tank is pressurized.

The fuel cap components seem to be all there and in good shape - the cap itself, a white plastic 'tray' and sponge, and a rubber gasket.

Any ideas on where to start?
 
#2 ·
Re: C21ZMR Gas Cap Vent - Solved

Vibration...

Between a broken mount for one of the two screws securing the front of the gas tank and (maybe) a worn/unbalanced blade there was enough vibration on the gas tank to cause the gasoline to froth and spurt out the vent. Anyway, that's my story and I'm sticking to it. ;)

The mount is an L-bracket welded to the recoil starter housing. The mount broke at the bend, so the screw remained in place and looked like it was doing its job at first glance. I'll have a new bracket welded this winter so in the mean time a rubber bungee was called into service to kill some of the vibration. That took care of most of the problem, but I also installed a new blade just because...and that seemed to help some too. I also checked and snugged up the mounting screws underneath the tank.

I'm a little concerned that there's enough wear and flex on the 18-year old plastic tank that the vibration issue won't completely go away, but so far I can avoid it by being careful with the fuel level in the tank.
 
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