Thanks for the wiring diagram and the details!

I went back out this morning and tried the jumper again still run (mostly) smooth.

Replaced the relay, still stalling.

But I listened a little more carefully this time. The car runs steady, and then I hear the relay click "off" and then occasionally ...

The relay is an OEM Volvo relay bought from a Volvo repair shop (not the dealer), new according to the repair shop, no reason to doubt them but who knows.

The relay itself is dated 2012, I assume that doesn't matter that much, the one I pulled out was dated 1998...

I have a bench power supply, etc ...

Hello folks,
My 1998 V70 Wagon was starting and then immediately dying (1-2 seconds). I read the other helpful posts (thanks!) and I removed the fuel pump relay and jumpered from pins 15 to 87, and the car started and ran like a champ (driving the 3 miles home from where I was stuck...)

I went out ...