New Fuel Pump Confusion

ILENGINE said:

The rollover check valve is a 2 way valve and is only supposed to stop venting when turned upside down. So the non venting fuel cap wasn't suppose to vent. You have a check valve issue not a fuel cap issue.

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ILENGIN, I appreciate the help. I had pulled that plastic valve out on first checking. I had no idea what it was for as I'm ignorant of ICEs. It clearly acted as a one way valve (you call it "rollover"). Found it at Partstree.com. When I suck on the line below the fuel filter, I can draw gas vapor from the tank. However, if I blow on that line, it is definitely shut off. Are you saying I should be able to pass air either way? It acts like a check valve and it can be shaken up and down (makes noise) when pulled out of the tank. So a new one breaths either way unless upside down?

masterdrago said:

ILENGIN, I appreciate the help. I had pulled that plastic valve out on first checking. I had no idea what it was for as I'm ignorant of ICEs. It clearly acted as a one way valve (you call it "rollover"). Found it at Partstree.com. When I suck on the line below the fuel filter, I can draw gas vapor from the tank. However, if I blow on that line, it is definitely shut off. Are you saying I should be able to pass air either way? It acts like a check valve and it can be shaken up and down (makes noise) when pulled out of the tank. So a new one breaths either way unless upside down?

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That is how they are supposed to work. The idea is to allow tank venting to remove the vacuum created by fuel leaving the tank, to allow vapor recovery so that it can be burned, and prevent fuel spillage if the mower tips over. Most of the time they never seem to work correctly.

I was just playing with an old one earlier, and it was restricting flow in both directions, except when turned upside down and then had unrestricted air movement in both directions.

ILENGINE said:

That is how they are supposed to work. The idea is to allow tank venting to remove the vacuum created by fuel leaving the tank, to allow vapor recovery so that it can be burned, and prevent fuel spillage if the mower tips over. Most of the time they never seem to work correctly.

I was just playing with an old one earlier, and it was restricting flow in both directions, except when turned upside down and then had unrestricted air movement in both directions.

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Now that is strange. Plus the picture of the rollover valve for my mower on PartsTree does not look anything like mine. Anyway, by venting the cap, any issues with the rollover valve are inconsequential. I do not mow on anything but mostly level 5 acres. Now my latest problem is that in my haste to get the tall grass mowed,I hit a root. Appeared to be no damage. Did not stop the mower, but when I shut down the blade and went to idle, the Kawasaki began surging slowly with a small backfire infrequently. Bet I nearly sheared the flywheel key. Now timing is off. Fun! Fun! I'll try to have a look in a few days. It continued mowing strong after the root encounter. Just surging and some slight backfire.

ILENGINE, the fuel cap (OEM) "is" vented. And the rollover valve is only one way "to" the connection under the air filter. I added more venting to the cap by drilling a small hole and added a screen to prevent debris. Dirt and dust must have clogged the original air path in the cap. New hole fixed the issue. No one I've talked to has ever mentioned a clogged fuel cap causing the dying as in post https://www.lawnmowerforum.com/threads/dies-choke-very-touchy.79518/#post-511460 and most recently zero pumping of fuel to the carburetor.