One gentleman before stipulated that it could be the RPM sensor. I propose a simple test for the pump and relay that does not involve undoing a single screw.

First, try to start the car. If it dosn't start, then we can test it for pump activity.

With the key in position II (Run), turn off the radio and close the windows. Then turn the key to 0 and pull it out. Put the key back in, and turn it to II again, and listen for a mid-range buzz coming from the rear end of the car which turns off after a 3 or 4 seconds.

If the buzz that dissapears is there, go ahead and try to start the car... If it dosn't run, test over. If it does run, you'll need to rerun the test as soon as the car fails to start again.

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My 1994 850 had the fuel pump die last year - driving along at 35 mph and then engine just stopped... eventually got it started again and parked, then drove it to the closest shop (hoping it wouldn't stall again) and a new fuel pump solved it.

My 96 850 had the cam position sensor go out suddenly while still under warranty. Would check that first.

Could also be the camm shaft hall affect rotation sensor. This is a somewhat common failure. If I remember correctly the fuel pump won't turn on if the sensor is not picking up any engine rotation. Very easy to replace.