Gas tank venting on a 163cc Briggs mower engine

N

nbpt100

Well-Known Member
I am working on a nearly new Toro Super Recycler stow and go model with a 163cc Briggs. 1000 series engine. There is a gas tank venting issue. This model has a larger gas cap than most of the Briggs walk behind lawn mower engines. It seals with an oring on the ID of the gas tank neck. It fits very tight. The tank is not venting causing the engine to be starved of gas. I am trying to find the vent and can not. It does not have a tube that runs in to the air filter box like many have. I am looking in the cap for some kind of tiny hole or passage way but can not find one. I see nothing in the vent neck that would constitute a vent of some kind. What am I missing.
 
Most likely the vent is in the cap which also has a charcoal filter canister built into it. So the charcoal could be gas logged, and basically bricked.
 
As you can see the gas cap is pretty expensive at over $30 with tax. I see aftermarket ones at half the price. To those who have experience with these caps, Are they worth it?
 
there was a youtube on it recently. The new caps lack the hole. It has to be in a certain spot to stop gas from sloshing out. Starts about 5 minutes

 
nbpt100 said:
The cap is #84004416 which replaces 594061. I do not see any vents in it. I respect your experience but I have no idea how this can work. Look at the cap in the link and tell me if you still think that cap has a charcoal canister.


Click to expand...
The cap contains charcoal. They have since around 2003-2004 when the new emissions standards started kicking in. It was one of the first thngs that took place. And the vent may not be a hole. It could just be a loose connection between two parts that allows air passage.
 
That video seems right on. Some Briggs mower engine tanks are vented and the caps do not need a vent. Some are not. The tank I have on this 163cc Toro is not. It appears to be a larger tank that they put on the premium mowers. It is being assumed Briggs confused the two different gas caps at the factory since they look identical. I have notice the color of the Orings may be different.. Grey and Black. That may be random but it would be smart to make it a distinguishing feature. Some may have charcoal in them but that is not my problem. It is the wrong cap for this Engine. The video suggests drilling a 1/16 hole above the o-ring to vent it. That is what they have been doing in their shop. This is not an isolated problem as they alone have seen it more than once on newer Briggs powered mowers. I am more inclined to drill a hole about .031. Heck. a .010 hole will work as long as it does not plug up. Thanks!
 
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