Fuel Pump Check Valve

Hi all -

Great news - after a very long time of chasing lead after lead, I've finally found the culprit for my hard start - gas is flowing back to the tank, oddly through my new fuel pump overnight.

I ended up putting a clamp on the hose that sits between the fuel filter and fuel rail, waited 24 hours, then cranked the engine and it started right up. The odd thing is if I manually trigger the fuel pump to pressurize the rail, then crank the engine, it still acts as if the rail is completely dry - which is confusing to me since the clamp method noted above is in theory keeping fuel in the rail in the same way as priming the rail by manually triggering the fuel pump would be.

This is the pump I have on it now - don't all fuel pumps have check valves or are they external and I simply don't have one?

I'm planning on splicing this check valve between the filter and rail (where my clamp was) which should work I'd think, or is there a better way of going about this?

Edited 28 minutes ago28 min by chaseincats