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

mstar

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
How much fuel should be in the fuel filter?
I recently disassembled and cleaned the Nikki carburetor on a17.5 HP engine. I replaced the needle as well as the gaskets.
And noticed that there's barely any
gasoline in the clear fuel filter. I have a photo that maybe hard to see but it was half full before I did the cleaning.
Now hardly any fuel is in the filter. I am wondering if this is normal or symptom of something I did wrong. I did mow for 20 minutes and did not seem to run out of fuel. But what caused the difference?
To be sure it wasn't a blockage, I removed the fuel line from in front of the filter and the tank drained with full force. I then refilled the tank and remove the line at the carburetor and it also drained fine after a couple seconds. The filter is a couple weeks new.
IMG_20171022_160624~2.jpg
IMG_20171103_151840~2.jpg
 

reynoldston

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

Rivets

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
Agree, normal.
 

mstar

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
Good to to know.
Can someone explain why before the carburetor rebuild it would be always at half but after so little? Did I have a micro leak that was allowing air in?

Since I bought this mower I had drained the tank . One was to change the filter and one was to remove the shut off on the bowl to drain. Each time that filter was half full and after carburetor clean, the amount is very little.

I am glad it is normal but I am curious why that changed.
 

ILENGINE

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
It is normal for the filter to fill when sitting, but appear to empty out when the engine is running, or after you shut off the engine. It has to do with the filter being on the intake side of the fuel pump and the pump reduces the pressure in the fuel lines when running and the filter acts like a restricter as well as an expansion tank, therefore causes the fuel to vaporize in the filter. Different filters will fill at different rates due to variations in filter media.
 

mstar

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
I will see if I notice it but over a two day period it did not fill up any more. Before cleaning it was always half full. As long the new level works, I fine with it .I was just curious about why it changed states.
 

bertsmobile1

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
The fuel inlet is flush with the end of the filter body but the outlet is a tube that goes all the way to the end of the paper cone,
Thus you get air trapped in the end of the filter.
Usually with bouncing around the ait will find its way into the outlet and the filter will fully fill.
Some times I put them on backwards for cutomers who do not understand fluid dynamics and think it should always be full.
Different bands of filter will have a different outlet tube length.
The long tube is to support the weight of the wet paper element.

From a filtering point of view it makes no difference which way they are fitted other than the junk will be inside the paper so you can not see it.
 

mstar

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
Thanks. This is all well and good. However, the answers are about why it is normal to have little fuel in the filter.

What I am asking, and Maybe no one knows, is why the same filter would be half full, all the time, and after the carb service is at very little. It is the same filter. Was it a sign something was not as tight in the carb an was leaking air so more gas could leak in?
 

BlazNT

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
OK so if you want it full then put the filter on the gas tank side first and wait till it fills up then put the carb side fuel line on. Its level has to do with the way you put it on. Trying not to spill fuel.
 

mstar

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  • / How much gas should be in the fuel filter? Reduced gas in filter after carb rebuild.
OK so if you want it full then put the filter on the gas tank side first and wait till it fills up then put the carb side fuel line on. Its level has to do with the way you put it on. Trying not to spill fuel.

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.
 
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