You may have a fuel pump problem. The fuel pump may be allowing fuel to seep past it when not in use so the fuel line will have nothing in it when you go to start the engine. You have to crank the engine to get the oil pressure switch to engage, which enables the fuel pump.
A quick test would be to bypass the oil pressure switch and listen to see how long it takes for fuel pressure to build. Initially the fuel pump will run fast when pushing fuel, but when it reaches pressure, it sounds like it is bogging down.
My 76 Vega fuel pump has a little bit of seepage, but it doesn't go too far overnight and usually gets pressure after a second or two.