How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.

[cpurvis]

Go to the nearest university that has a school of engineering, seek out a Fluid Dynamics professor and ask him.

He will immediately begin spewing out Greek-letter named variables that explain the balance of pressures in painful detail. Painful, incomprehensible detail, but detail, nonetheless.

disclaimer: I do not know why. I can only fathom an "IF, AND, THEN" type guess.

IF the filter is on the suction side of the fuel pump, AND something is causing a restriction of flow between the fuel tank and the filter, THEN the filter is a space in which fuel can vaporize, causing a bubble.

Gasoline vaporizes readily. That's what we like about it. (Unless it vaporizes before it gets to the jets.) It doesn't take much of a pressure decrease to vaporize gasoline.

 

[BlazNT]

It is OK if you dont know the reason. The filter was not removed or changed. Same direction in each case and installed as the arrow on the filter shows.
I am not saying I want to have it full. At first I wanted to be sure this was not a sign of something negative from working on the carburetor . Please understand this. I understand it is working fine as it is the lower level.. That was not the question I have been raising since then. . The question was out of curiosity of why there was the level change that was immediately noticed as different.

Ok. so you remove the gas line when you worked on the carb? Did you raise the fuel line above the gas tank so gas would not leak out? Did you drain the tank so it would not leak? Did fuel have time to evaporate out of the fuel filter? I would think you would have had to do one or more of the things I asked about which would change the fuel level in the filter. This is only guessing.

 

[mstar]

So when I changed the fuel filter the gas was drained from tank and lines as I bought it used and wanted a fresh start.
The filter filled up to the level seen in the first photo. There wasn't any delay. When I fully tested the mower I wondered about a surge on start up and it was suggested it could be Dirty carb. So I put Seafoam into see what it would do before taking off the carb. I thought maybe there could be a mess in the bowl so took off the fuel line from the carb and drained all through the filter if I recall. I did not have a shut off nor did I want to crimp The line so I just thought it was easy enough to drain since I didn't have a lot in the tank.
No matter where the line was disconnected, the filter Always returned to half full in short order.

I reset the valve spacing and when that did not solve my issues, I went the route of removing the Nikki carburetor to clean. It was very clean inside. I ran a wire and cleaner through all the Jets and such to be sure.

I replaced the needle and paper gasket and bowl gasket.

Yes, the tank was fully drained by taking the line off at the carburetor and drained it through the filter into a jug.

It was only after I put it all back that the amount in the filter changed. I ran it for 20 minutes and it was fine, sat a few days, no level change, and I had it running to adjust the cable and fuel mix screw. Level still as photo 2.

What some are getting hung up on is trying to tell me why the level is so low and it is normal.
As I said, great I will take it!
However, why it was different than before was not explained. I was only curious.

So my educated guess is that air was leaking at the carb enough to allow more fuel to enter the filter.

 

[Boudreaux In Eunice La.]

I can buy 10 filters from the same shop and each one will have a different level in them. Barometric pressure has a lot to do with what you are talking about.

You are getting into the brass tacks of things when you ask a question about why did it do that. Simple.........

Look at your coffee cup when you pour coffee in it. If the bubbles go to the outside of the cup then it's high pressure. If the bubbles stay in the middle then it's low pressure..... Thats your barometer right there.........

 

[mstar]

It is the same filter. Not same type...it is the same filter in both photos.

 

[panabiker]

You can fill it up by tilting the outlet side of the filter up (the side with yellow clamp) when the engine is running. The carb will start sucking the air out of the filter chamber. If the carb is working properly, the engine should run normally but the filter will be filled. Activating the choke will speed up the process.

 

[mstar]

Thanks but I am not asking for how to fill it. I am not trying to get it back as it seems to be running with the lower level.
I while I had concern when I first posted, now merely pondering the reason for the difference.