I've only driven the car for about 2 hours, so I don't really know if it's a problem or not.

I've got a clear fuel filter (not the cheapies, it's got a thick, Pyrex body) installed AFTER the mechanical pump, and BEFORE the regulator. According to the gauge installed at the regulator, the pump delivers a constant 6.5psi to the Road Demon carb.

I just thought it was strange that there is usually almost no fuel in the filter. At most it's an 1/8th full, and most of the time it's completely empty! But the car still runs. When the filter empties out after a minute or so, it will refill with another ounce or two of fuel, then will get sucked out and into the carb, and will cycle over and over. The float levels remain satisfactory, also. This is with a full tank of gas, and a new sending unit. It happens with the fuel cap on or off, and the engines does have a slight surge (100-200RPM) at idle.

The car seems to run OK, but I'm worried it will run out of fuel at the top end of the 1/4 mile. Maybe the fuel pump is sucking in some air? Any ideas to this strange problem?

I had this same problem after I installed a Carter 120 street pump. I posted the problems last year, I believe in the engine forum. Maybe do a search on my username.
I had a stock pump on before that would keep the filter full when running. The Carter delivers 6 psi as it's supposed to, and with the line unhooked pumps a solid stream of fuel, but kept the filter almost empty.
I got tired of trying to figure it out and eliminated the filter. I use a fine mesh brass screen that I put in the inlet of my Q-Jet behind where the GM filter was originally. Got it at a Farm supply store and cut it to fit.

EDIT: Search the Engine forum under "Mechanical fuel pump observations" on August 03, 2002.

Yes, I read that post. Strange how this happens, and I don't know whether or not it is actually a problem. I do have a big filter (Like the Fram HP1, but made by Mallory), but it's hard to find a place to mount it.

I think the problem is I can SEE the problem. If that filter wasn't clear, I wouldn't be posting this.

I have a clear in-line filter on a MG and I've never noticed it being full. I wondered about it a while, but it runs, and with that car there is plenty of other stuff to wonder about.

Anyway, this filter is installed horizontally, and I'm guessing yours is too. I think it fluctuates with air displacement/pressure/fuel demand.

Maybe if it's upright it'll fill up with gas. There's probably a scientific explanation. One thing I'm pretty sure of, and that's that in order for it to fill completely with gas the air has to leave.

I ran one of those also, a couple years ago...and same thing, I wondered why it was never full. I have an Earl's aluminum one on there now, and Im SURE this one is full at all times :D Dont worry about it I guess, or get one you cant see through. John

I have a new Edelbrock Hi Perf. street mechanical fuel pump (110+ gph) and a clear fuel filter before the carb. The filter is never full. It has made me wonder if there is air in the system. The car runs fine.

Theo