There must be some way to check a fuel pump relay on a 380 sl. Maybe by energizing some pins at 12 V and then checking for open or short circuits on other pins????
Any ideas. And my pins are not numbered 1-7. They are top row:15, 31, 87 and bottom row:50, TD, 30, and 87k.
Thanks for any advice you may be able to give me.

You shoud be looking at the pins on the connector, not the relay. I don't want to steer you wrong on the numbers, so don't try this without confirmation, but on my 380SE it was pins 7 & 8 jumpered together.

I had the same on my car today, the wife comes home and parks the car in the driveway and the car shuts off by it self. Next time it's to be used it didn't start up, but cranked well. Seemed electrical to me, i read the threads and got to the indication of the fuel pump relay. No power on the fuel pump when cranking the car, I jumped 30 and 97, ( 7 and 8, reading the socket ), it fired right up. ( that's for mine 380SEL 1982 )

I belive it's about $135 here on fastline, well since I had to wait why not pull it out and look inside maybe solder joints, like happens on the idle box. Sure enough one of them looked cracked, took 5 min to solder and the car was running fine as before. I don't expect it to hold another 20+ years but maybe a couple.