Try a new EVAP purge Valve....cheap and easy to test/replace.
The EVAP Purge valve is the gatekeeper for allowing fuel vapors from the tank (via the charcol canister) to be sucked into the intake manifold and burned in the engine (vs released into the atmosphere, which is a no no).
If that valve is stuck open, the engine will constantly be pulling fuel vapors into the combustion chamber, which the ECU is not expecting, and as a result you will receive the following issues:
- Reduced performance
- Reduced MPG
- Poor starting especially after filling up
- Lumpy idle that lasts a few seconds or outright stalling.
You may not necessarily get an Engine warning light either.
You can test by removing the valve and trying to blow through it....You
shouldnt be able to blow through it unless 12 volts is applied to terminals.
When you apply 12 volts, you should hear the valve 'click' open.
If valve does click, you can spray some electrical contact cleaner (or even WD40) into the nozzles, then activate the valve a few times to help unstick the valve.
I had this issue on my V70 recently...The 22 year old purge valve was stuck open, and applying 12 volts did nothing. The valve was completely stuck, so I replaced it.
Video from a Mazda 3 (with same engine as your Volvo) showing the purge valve replacement.
LINK for fullscreen:
Mazda/Volvo/Ford 2.0 duratec purge valve