1992 Plymouth Voyager started then quit

Unlike GM pumps, Chrysler pumps rarely quit while they're running. They almost always fail to start up. If the engine ran for a few seconds, that was from the stored up fuel pressure in the lines. Try banging on the bottom of the tank while a helper cranks the engine. Very often the jar will get it going for up to a few weeks.

Relays don't fail often either. A quick test is to just swap it with another one like it. The AC compressor, starter, and automatic shutdown (ASD) relays are all the same.

Caradiodoc

I see your problem. My '95 has a fuse box under the hood with the relays in it. For '92, it's like my '88 with the relays mounted on a rail on the left inner fender.

There are four relays shown in the diagram. Starting from the rear, they are radiator fan, automatic shutdown (ASD), starter, and fuel pump. The fuel pump is spaced a little further away than the other three to make room for the rail's mounting bolt. You need the starter and ASD relays but you might be able to swap the fuel pump and radiator fan relays. I don't know if they're the same.

Another trick is to pop the cover off the fuel pump relay, plug it back in, and watch for a tiny spark when you squeeze the contact. If there is a spark, that proves current is going to the fuel pump and it should be running. You might try wrapping a rubber band around the contact to keep the pump powered up, then bang on the tank. You will hear the pump run if that gets it going. At that point the engine should start.

Caradiodoc