Why is it slow to start only after filling up?

[pff]

Sounds to me as though its goosed chief.
As CarlW says I would advise replace the hose, I used 6mm fuel hose it was ever so slightly too small, maybe 6.1 or 6.2 ID if that exists, take the dirty valve into halfords and try them out dont take my word for it.

My car was giving a groggy start up after fuelling but an engine light for upper fuel trim at idle rpm, but no code for intake air leak so it cant have been too bad.
When I said about fuel vapours flooding the engine yes, I meant drawn in by the intake manifold pressure. Also if there is a leak and your fuel trim is up to compensate that's more fuel in there when you start plus whatever is drawn in from purge so a very rich engine indeed.

To test I used a heavy spring clamp on the manifold-solenoid pipe to isolate the purge system, a change in engine note was immediately noticeable indicating an air leak via the hose/valve.

If you have vida/dice it also holds your hand through different tests for checking the purge system but it gave me the green light several times before I ignored it and took matters into my own hands.

[Joe H]

Great, thanks to all. I now understand better what should be happening and will do some more investigation with VIDA. Not sure what material the original hose is but yes, it did feel pretty cruddy so it seems sensible to change that.
Cheers
Joe

[SteveSarre]

Hi Joe

While you are looking at hoses, that perished hose leads down to a semi-rigid nylon pipe which goes down beside the radiator then across to an L piece which is a push fit on the carbon canister towards the left front wing.
Make sure that L piece hasnt fallen apart too. You can use a length of straight silicone hose, but I recently bought a Volvo original part 9135342 for about £4.

I am still puzzled about what is causing your problem. I wonder if it would be worth testing two situations:
Drive until car is warm, turn engine off for 5 minutes (about as long it takes to do a fill up), (but do not fill up) then restart. Start OK?

Drive until car is warm, turn engine off for 5 minutes (about as long it takes to do a fill up), open fuel tank cap to release pressure (but do not fill up) then restart. Start OK?

Hope that helps,
Steve