Engine runs only with loose gas cap

ukrkoz

Well-Known Member
Joined
Jul 2, 2017
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Based on this post:

https://www.tractorbynet.com/forums/parts-repairs/413230-whats-wrong.html

anyone has any ideas? I must mow next week and this mower decided to start acting up on me - after I sold my ZTR last week. Of course. Karma.

Good folks at tractorbynet said to clean vent in cap - that's real basic cap, I see no vents. Unless it's those 2 cuts in the cap edge on its either side. I got to have that mower going and going well.
Also, what I do not understand is - why it will run fine, even with blades engaged, sitting in place but will choke when I start moving forward, what means - blades start cutting. Unfortunately, the way it is, it has centrifugal clutch and you can't rev engine without engaging rotor/blades.
It does sound like something is wrong with fuel supply. Looking at gas tank, gas is not gravity fed, but is sucked up via filer (?) and into the engine, so engine creates suction for that, right?
Help will be really appreciated. Even if I have to rig something, I don't care. But I can't really run it with gas cap off, there's too much debris flying everywhere. They WILL get into the tank. Plus, gas spilled out...
 

ILENGINE

Lawn Royalty
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May 6, 2010
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10,732
From your description it sounds like it was manufactured after 2012 which means the cap is non vented. the plastic thing you describe would be the tank vent slash rollover valve. That hose that connects to is either should go to a round/rectangle shaped box or to the air filter side of the carb. Either way it sounds like the charcoal canister has been gas contaminated and bricked the activated charcoal or the rollover valve has stuck shut.

The gas outlet for the tank should be on the bottom of the tank.
 
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