Leaking Connection at Fuel Pressure Regulator

I just finished replacing the head gasket on a 1992 Cavalier, 2.2L. All has gone well until I started the engine. Fuel spilled out from the line going into the pressure regulator. It did not leak when I began the work nor when I turned the ignition switch to "on" (post repair) without the engine running. It only leaks with the engine running.

When I first disassembled this connection I saw no o-ring seal (like on the return line). Maybe it fell out?

I re-tightened the connection without any luck...still leaks out the bottom.

I cannot find any info on what, if any, seal belongs on the hard line going into the fuel pressure regulator.

Can anyone advise?

Thanks!

There is an o-ring that is supposed to go there. You might have lost it, and it will not seal without one. You might take the regulator into an Auto Parts store, and find a replacement o-ring