Greetings to all, this is my first post. I replaced the mechanical fuel pump on my 74 EC. It has a 350 engine. It leaked fuel out of the pump when I started it. It appears to be at the junction of the fuel line and the pump (outlet). I know the fitting was tightened properly so I figured I got a bad pump (auto zone). After mounting the second pump and installing a new brass fitting I fired it up. It leaked again! So, I ordered a new AC Delco pump and a new steel line. Attached the line with Teflon tape and torqued it up. On a hunch, I left the vent line off the pump. When I started it up, it spewed gas out of the vent line of the pump! What could be going on here? I am a former auto tech with 33 years experience on the "old stuff" I have never had to replace a fuel pump more than once. I am truly stymied. I bought this 2 months ago. It has been butchered quite a bit. I am working my way through the previous bad owners "fixes". Please help. Thanks

 

Vent line, is return to tank. These are flared fittings, so if the flare isn't correctly mated, no amount of thread tape with stop it from leaking. I've seen these things with a diaphram leak, and pump the crankcase full of gas.