Cutting out / idle dropping / fuel tank noise after long drive

[pauljsgreen]

Hello again.

2000 Boxster S approx 70k miles. No fault codes stored. Unknown history other than me for the last year or so.

MAF cleaned, throttle body cleaned - no change.

UK summer approaching and the boxster’s getting its startup maintenance planned – not been used all winter.

One problem I had all of last year was that, after maybe a 20 mile drive @ 70mph (motorway / freeway), than enter a city and drive in stop start traffic for another 2 miles or so, the engine revs get very uneven and drop to a point where it almost stalls. Usually it picks up, but if it doesn’t, it stalls and is difficult to start.

All of this is usually accompanied by a fairly loud groan from the fuel tank area. Sometimes, removing the fuel cap, pressing the flap and letting a bunch of air in (or out?) helps the starting if it stalled or smooths out the dropping idle speed.

I have a new fuel filter that I didn’t fit last year, so I will do that shortly, but I was looking for some advice as to what other areas to tackle.

I appreciated you taking the time to look.


Many thanks
Paul