Can anyone describe to me the locations of the fuel pump relay and reference sensor on my '94 850 wagon? (non-turbo model) I've been told one of these parts my be the cause of my intermittent no start.

In my experience with European cars, the fuel pump relay is the first thing to check. have seen this on a couple of my Volvos, as well as BMW and Audi. Dealer list is around $40, but pull yours out and see if it's a normal 85-86-87-30 or 85-86-87-87a-30 configuration, available at autozone or pep boys for around $10. Here's something I found in the archive:

Re: Where is fuel relay located?𖛊/93] posted by abe crombie on
Saturday, 2 December 2000, at 9:25 a.m.
--------------------------------
Fuel pump relay is in the back end of the fusebox. You have to remove the box top to get at it. It is labelled "103". The fuel system relay for powering up everything else is clipped to the top of fan shroud. The fuel or ignition control units may not be secure in their base connectors. You might try removing and re-installing these as the first effort at this problem.
--
(98 S70 T5SE misc mods - mostly lighting - and red calipers) (92 940GLE)

Following information is from my service manual for 1993 850 GLT. Yours should be similar.

The Fuel Pump Relay is located next to the fuse box, under a cover, with other relays. It is second from the right on the row closer to the fire wall (there should be two rows of relays). To open the cover, remove torx screws.

"reference sensor" sounds very generic. I can try to look it up if you can provide more information. Air/flow meter & throttle position are the two sensors in the Fuel Delivery and Air Intake System.

Later.

Here is a diagram,

fuel pump relay
'
------ -- ---
| | | | | |
------ -- | |
-- -- -- | |
| | | | | | | |
-- -- -- |--|

sorry it looked fine when I drew it.