# Fuel filter on Briggs & Stratton



## DHeraud (Sep 12, 2014)

Hey guys and gals,

Is it normal for the clear fuel filter of my riding lawnmower to be filled so little, even while operating (see picture)?

The mower is a Bolens St-140 with a B&S 294777 engine.

I have checked the fuel line and fuel flows freely. I don't get any stuttering from the engine while running idle or 3/4 throttle, however I find the engine is very sluggish and had trouble going up a small incline. Any ideas? Bad fuel pump maybe?

Thanks for the help!


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## DHeraud (Sep 12, 2014)

Picture didn't seem to work, let's try that again.

https://www.dropbox.com/s/90bh75blila3qao/20141105_110824.jpg?dl=0


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## jhngardner367 (Apr 5, 2011)

Wouldn't hurt to check the fuel pump.
Do you see the fuel surging into the filter,or is it more of a bubble you see?
Check the vacuum tube from the breather , to the pump,as well.


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## DHeraud (Sep 12, 2014)

Not quite sure how to "check" the fuel pump...?

When the engine is running, I don't see any fuel surging into the filter at all. There isn't more or less fuel in the filter when the engine is running.

I did check the vacuum tube though and it looks just fine.

I ran the engine for over 10 minutes, wouldn't it have ran out of fuel (or sputtered at the very least) if no (or little) fuel was making it through the pump?

Tomorrow I'll try to see if fuel makes it out of the pump by disconnecting the pump-to-carb tube and turning the engine over to see if the pump works at all.


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## Halifax (Oct 8, 2009)

Not sure if this is helpful but ive got a generator with a b&s engine. The filter similar to yours never fills up. Never gets close to half full, its like the air will not rise back up to the tank allowing fuel to flow down. Runs great as is. I can pre fill the filter and it will stay full, but when i run it dry it never comes close to half full.


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## jhngardner367 (Apr 5, 2011)

These filters will "air-lock" like that,yes. Try burping it,as you mentioned,with the line off the carb . If it fills,then it was air-locked. If not,check the pump.
These engines will run,without the pump,but will act sluggish,or stall,if the throttle is opened.


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## Fredneck (May 25, 2012)

i wouldn't make any judgement about how full the filter gets. over the years, i've seen vehicles cover the spectrum - seen some filters fill right up, and others barely fill at all, and anything in between. not saying there's nothing wrong with your system, but i am saying i wouldn't come to such a conclusion based on how much fuel is in the filter.


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## DHeraud (Sep 12, 2014)

Fredneck said:


> i wouldn't make any judgement about how full the filter gets. over the years, i've seen vehicles cover the spectrum - seen some filters fill right up, and others barely fill at all, and anything in between. not saying there's nothing wrong with your system, but i am saying i wouldn't come to such a conclusion based on how much fuel is in the filter.


Interesting... Can you explain to me how the engine can get enough fuel then? Looking at my own filter, I just don't see how the fuel goes up the line as the filter doesn't even fill up to the tube that goes to the fuel pump.

Anyway, I'll be testing the fuel pump later today and will report back.


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## DHeraud (Sep 12, 2014)

Well just turned the engine over and I've got gas sputtering out the of the fuel pump on the carb side, so don't think that's my issue.

Maybe I'll post another thread more specific to my low engine power issue.

Thanks for the help everyone!


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## DHeraud (Sep 12, 2014)

*New thread*

Here's the new thread:

http://www.tractorforum.com/f181/briggs-stratton-engine-feels-sluggish-low-power-28704/


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## Fredneck (May 25, 2012)

DHeraud said:


> Interesting... Can you explain to me how the engine can get enough fuel then? Looking at my own filter, I just don't see how the fuel goes up the line as the filter doesn't even fill up to the tube that goes to the fuel pump.
> 
> Anyway, I'll be testing the fuel pump later today and will report back.


i have no explanation for how it works, i only know it does. i've got a friend with an old truck which runs fine with barely any gas visible in the filter.

if i had to guess, i would say that the filter element itself acts as a wick, and as long as there is fuel touching it at any point, the filter material itself becomes completely soaked in gas, and the fuel pump is capable of drawing that gas from there.

again, that's only a guess.


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## DHeraud (Sep 12, 2014)

Fredneck said:


> i have no explanation for how it works, i only know it does. i've got a friend with an old truck which runs fine with barely any gas visible in the filter.
> 
> if i had to guess, i would say that the filter element itself acts as a wick, and as long as there is fuel touching it at any point, the filter material itself becomes completely soaked in gas, and the fuel pump is capable of drawing that gas from there.
> 
> again, that's only a guess.


I agree that does seem to be the case.


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