Re: Fuel bowl draining …

Posted by Fish'n Jim On 2021/9/15 20:00:40

You got an air leak somewhere, as Kevin noted on his car. Air leaking in, suction is broken, that's what's causing the fuel to drain back. The fuel pump check valve(s) must be faulty to allow back flow. There's been a lot of issues with new replacement mechanical fuel pump valves since they moved the manufacturing. Once it's liquid full there's not any good reason for it to "disappear" and not leak liquid.
Liquid seeks it's own level, so once the motive force (pump is off) the gas is seeking it's level and draining back to the tank. There's not enough volume change in the tank (large surface) to displace any vapors to cause a smell.
The flares should be SAE double inverted on the fuel line, unless you switched to AN fittings.
Much misinfo about fuel bowls because they've been out or use for so long. If it was "boiling" out you'd see bubbles. Plus only about half of the ethanol will evaporate. It co-distills with some hydrocarbons and once it's a certain fraction, BP raises enough to stop the boiling, plus the car is cooling off once it's off.
You're better off finding and fixing the leaks than installing a booster electric pump. I've had so many bad mechanical pumps come through I've gone to complete electric on the Cad, but you have to do a bunch of safety wiring so it shuts off and turns on when starting. Not straight forward but there's info on net and form Airtex.