What can make a fuel filter look empty?

[Tom]

and make the car not run or barely run and then snap out of it and run good for awhile and then do it again and last for hours or days ans then all of a sudden it's OK again.

Vapor lock is the first thing that comes to my mind but how to you find our what is causing the vapor lock?

[Kraig]

Carbed car? Maybe your float is sticking in the up position so no fuel would flow, then it unsticks over a bump? Tap the carb with a rubber hammer and see if it unsticks, if so a carb rebuild is in order or maybe your fuel pump is fubar.

[miami man]

kraig may be right. my mothers 66 chevelle did it years ago and we kept a hammer in the car and tapped at the needle and seat area to get it running. it would do it off and on.

[packrat427]

Are you talking about a external fuel filter , or the site glass on the carb .

[Tom]

the external fuel filter on the fuel line befor the pump.

[packrat427]

A sticking float , or a carb problem will not cause that filter to be empty .

Maybe a weak pump as it gets hot ?
Maybe the pick up in the tank is partially restricted .

It may have been suggested before ... blow air back thru the fuel line to the tank .

[89fester]

There could be a cracked or dry rotted fuel line somewhere that is letting air into the fuel system. Even the pickup tube in the tank could be rotted and pulling air from the tank. I think thats about the only way you would see air in your fuel filter while the car is running, no?

89 L

[Tom]

When it starts to stall and will hardly run at all and I look at the fuel filter it looks like it is empty. When I'm running good it looks full. I changed fuel pumps and filters and the screen in the gas tank looks clean.

Could this screen in the gas tank be the problem even though it looks to be clean. I almost left it off. The end of the fuel line is cut at a angle so if the screen was to go up to the line you would think it would still feed plenty of fuel? I'm at a loss.