Car didn't want to start... then did! :Confused:

[27litres]

Interesting fault today.
It was a warm day today, about 32°C.
My car had been parked at Ringwood in the sun all afternoon when I jumped into it about 7:15pm (still 28°).
I then drove it to Upper Ferntree Gully, around 13km (8 miles) to go shopping on the way home.
The car got well heat soaked during the trip and had noticeable drag and noise from the engine fan.

It was about 15mins by the time I returned to the car.
And it decided it didn't want to start!
It turned over fine, all lights on the dash extinguished as normal, but it would not catch, or even stumble.

No immobiliser issue, those lights went out fine (and it wouldn't start at all, the immobiliser starts and stalls).
No CEL.
I haven't scanned it yet.

I opened the bonnet and performed an obvious fault scan, and checked the vac hoses (they're on the replacement list). Nothing obvious there.
Superficially checked power connections, everything was fine.
Tried to listen for fuel pump priming, but couldn't hear it (the current pump is about 5 years old).
Plenty of fuel, oil, coolant.

Turned it over one last time from outside car to listen for injector firing when it immediately started.

Drove completely normally the rest of the way home (8km/5miles largely up hill).
Tested a restart once home - started normally.


So any ideas?
Fuel pressure regulator was renewed when the pump was replaced (5 years).
Can the fuel pump relay behave badly in hot weather?
Anyone had other heat soak issues? CPS for example?

Appreciate any ideas. Its only getting hotter for the next 8 weeks!