[lucky1]

I have clear gas filter. When the motori is running sometime the filter is full.

Other times the filter is mostly empty,

Can anyone explain this ?

The engine is running normally and I have a continuous electric pump.

Thanks.

[Mike Davis]

Is this a glass filter? If so do yourself a huge favor and get rid of it. I have seen alot of those break. Seen one break on a T/A and burn the car to the ground.

Do you notice a difference after it has been driven vs just starting it up?

[steve25]

That's perfectly normal what your seing ( not seing ) but what you don't want to see is as posted above!
Get rid of that glass filter before the next time you even fire up the motor because I have seen a running motor with its nose half way in a garage catch fire and burn the house down!

Get a nice big steel cased fuel filter rap it in some insulation foam and mount it in a good air flow area and forget about looking at your fuel flow at idle!

[JSchmitz]

Originally Posted by Mike Davis

Is this a glass filter? If so do yourself a huge favor and get rid of it. I have seen alot of those break. Seen one break on a T/A and burn the car to the ground.

Do you notice a difference after it has been driven vs just starting it up?

My '64 GTO nearly burned up because of one of those POS! I popped apart while I was driving. Had an electric fuel pump. Car died just as I was pulling into my parking spot. Smelled strong gas smell. Popped the hood to find it completely soaked with gas. Good thing that I had good plug wires! One open spark and it would have been a total loss for sure. The ends are made of cheap aluminum. The threads pulled out and it came apart. Get rid of it immediately.

[78w72]

i agree those glass filters arent safe & ive read the horror stories about them. however, back when i was a teenager before i knew better, i had one on a 78 ta with a mild 455, had it in use for almost 10 years with close to or over 100k miles, even took a 3000 mile round trip with it. it never had any problems & the ends werent aluminum, they were a chrome plated pot metal or something... think i still have it in a box somewhere but will never use it again. the screen filters inside do flow good though.

& it did the same thing the OP described, it was never totally full.

[JSchmitz]

Originally Posted by 78w72

i agree those glass filters arent safe & ive read the horror stories about them. however, back when i was a teenager before i knew better, i had one on a 78 ta with a mild 455, had it in use for almost 10 years with close to or over 100k miles, even took a 3000 mile round trip with it. it never had any problems & the ends werent aluminum, they were a chrome plated pot metal or something... think i still have it in a box somewhere but will never use it again. the screen filters inside do flow good though.

& it did the same thing the OP described, it was never totally full.

Mine were chrome also. Maybe it was "pot metal". My recollection was that it was cheap cast aluminum. Not sure though.

[Tom Vaught]

Related to a carb but the same idea, I still use the "older" Holley Fuel Bowls with the small Brass Threaded Plugs.
The Proper fuel level was set by having the fuel just below the bottom of the sight plug hole. The front and rear bowl heights are different.
Bump the fender and if you got a drip out of the bowl you are good to go.

Point being the newer fuel bowl sight glass is not made of glass, I have been told.
Possibly a form of plastic. Might be glass though. Can't believe everything you are told.
I will stick with my FIRE-PROOF brass plug design, especially with a electric fuel pump.

Sorry for the diversion on the fuel fire potential.

Tom V.

[lust4speed]

Back to the original question. I would speculate that the "air" is fuel vapor that has separated out of the gasoline. Sort of along the same reason that fuel pumps that have a vapor return have the vapor return line at the top of the fuel pump canister to bleed off the vapor. If the filter was positioned with the exit at the very top this vapor would exit, travel into the carb and exit the carb vent. On cooler days there would be less vapor and warmer days more, and the position and motion of the filter while driving will naturally purge some vapor out the exit and limit the amount that you see.

[lucky1]

Thank you all.

I am aware of the hazards of plastic and gas filters.

I temporarily installed this one to check a fuel deliver problem.

Thanks again.

[Formulabruce]

Originally Posted by lucky1

Thank you all.

I am aware of the hazards of plastic and gas filters.

I temporarily installed this one to check a fuel deliver problem.

Thanks again.

Be worried about the rubber seals getting ruined by alcohol.