HELP! Van will not start - Fuel suppl - Fuel press. Ctrl?

We had a similar problem very recently, and it ended up being a bad ground connector at the connector under the driver side near the fuel tank.

We also jumped it at the relay and it ran just fine, but we had bumped the bad ground into a good spot and it would run for about 20 miles.

Interesting - I have found out the following:
the electr. Diagramm shows that the fuel pump will get power from the relais station but also from the oil pressure switch when the engine is running. Can you confirm that? After jumping the relais I started the engine - then pulled the jumper wire and the engine kept on running. I stoped the engine and restarted - no problem and all that without the relais or jumper in place. I left the van sitting until the next morning and tried to restart, again no jumper or relais. Itr would not start. I then repeated the proceedure from the previus day but this time the engine would not stay running -? I think I have two problems? Can you confirm mi suspitins?
Thanks for your help.

Sven.