Slow starting when left for a while, fine otherwise

[zcacogp]

Hi, 

My 2.7 987.1 (i.e. non-S) has a problem with starting when it's been left for a while, but works fine at other times. For instance, it had sat in the garage for a week until last Saturday. When I started it then it cranked for a very long time (probably 8-9 seconds) before firing. It fired cleanly with no hesitation and ran perfectly OK from that point on. I drove it for around 10 minutes before stopping to buy some petrol, after which it started again perfectly. I then drove for around 20 miles before stopping for a few hours, after which it fired up perfectly fine again. 

When it eventually started on Saturday it gave me a message on the dashboard saying (something like) "Engine problem, visit workshop", but didn't show an EML on the dashboard. I've plugged a code reader in to it and there are no codes logged. 

The problem therefore seems to be starting it when it's been standing for a period of time. Does anyone have any experience of this or any suggestions as to what could be wrong? 

My thoughts are whether there is a fuel pressure accumulator which holds fuel pressure in the injection rail when the engine is switched off, thus allowing high-pressure fuel to be delivered immediately upon starting. If this leaked over time then it would explain the symptoms, but I don't know whether there is such a thing on a 987 and hence this is guesswork. 

(FWIW I do know that the AOS is leaking and needs to be changed. I have a spare one and will do this job when I can, but other things are preventing me at the moment. I doubt this is relevant but mention it here anyway.)

All suggestions welcomed, thanks. 

[Boxob]

Battery?

[zcacogp]

Boxob, 

Thanks, but probably not. It had a new battery about 4 months ago, and lives on a CTek conditioner when in the garage (I disconnected the CTek just before I started it on Saturday.) 

[Menoporsche]

Does sound fuel-supply related from those symptoms.