I have a 502 MPI that’s in my Baja 272 , it came as a basket case so I’m trying to put it back together. Where do the vent lines from the fuel pumps ( the low pressure and the two vents on the high pressure pump) go? Any help would be greatly appreciated.

Can you post a picture of what it is you're calling vent lines? I don't recall having any such thing on my 502 MPIs.

On mechanical fuel pumps there's typically a vent line that is routed to a vacuum nipple in case the fuel pump diaphragm ruptures.

thanks for the reply, I have the low pressure pump diaphragm vent located but it’s the high pressure pump vents that have me curious. I attached a marked up photo

OK, that's the VST from the first gen MPI motors.

I think the vent line from the low pressure pump goes to the top input and then the "vent" one on top goes to an intake manifold vacuum source. Not 100% on that, but,

This thread has a couple of service manual pages that might be useful to you
1997 502 MPI Issues - Vapor Lock?