Calling all Volvo specialists!

So, basically, my car won’t start if it has sat under the sun for too long. Sometimes it will catch briefly, but then sputter and die immediately after. Sometimes it will just spin endlessly and never even threaten to work. Giving it throttle only seems to make it worse.

If I try to start it early in the morning (before the sun comes out) or after it’s sat in the garage overnight, it fires up immediately (although sometimes it will run a bit crap for the first couple of minutes until it warms up).

Sometimes, after driving for a little while and then stopping for a few minutes (for instance, to get gas) it will not start again. Resetting the ECU and waiting a couple minutes makes it fire right up again though. Perhaps it’s related somehow?

It’s a 94 850 Turbo, in case anyone is wondering.

Any ideas where I should start looking?