Disappearing Fuel

[3505jd]

I have a 74 Spider with a DMSA carb and an electric fuel pump mounted in the trunk. There is a clear fuel filter just ahead of the carb. On each start attempt I have to run the fuel pump for a long time to fill the filter as between starts the fuel in the filter 'disappears'.
Has anyone else experienced this problem and what was the fix?

[TX82FIAT]

Your fuel pump should have a check valve that holds pressure unless the valve has a leak. I would also ask a dumb question, where is the clear filter in relation to the height level of the carb? Lower is better provided you can still see the clear filter.

[3505jd]

Sorry for not responding earlier. The fuel pump is a Holley unit installed by P.O."s mechanic in 2017. I contacted Holley and gave them the part number. They were not able to tell me anything about the pump. I installed a check valve in the fuel line in front of the clear plastic filter. Both are mounted vertically and below the carb. The situation is better, but the gas still drains somewhere over a week or so. ???

[TX82FIAT]

I would suspect a small leak in the fuel line allowing fuel pressure to diminish the longer the car sits if the check valve is functioning properly.

[Nut124]

It's normal for the carburetor fuel bowl to run low after sitting for some time due to evaporation.

A good fuel pump should fill the carb in seconds. I'd check the fuel lines for blockage. Carefully disconnect the fuel line at the carb and direct it in a safe container. Then run the pump and observe the flow rate. Compare this to specified flow rates of approx 20-30gph.

[3505jd]

Checked the fuel line for leaks and didn't find any.
The fuel pump will fill the line in a few seconds so I don't suspect that it is faulty. I can live with the rate of drainage or evaporation. I only drive the car on weekends in spring, summer and fall which combined are only six months of the year where I live.