Engine stops running after 15 minues

[ron.in.irvine]

1997 Boxster, auto transmission, 116K miles.

Drove perfectly running Boxster to the hardware store, spent a couple of bucks, and returned to find that it wouldn't start.  Starter motor turned and engine turned but wouldn't fire.  Instrument panel worked, headlights worked, etc. 

 

Took a couple of hours to get it transported home and found that it then started immediately.  Left it alone until the next day and started it again on first key turn.  Discovered that it would run for a few minutes and then stop without showing any warning lights or showing codes on my standard OBD2 tester.  Just stopped running and wouldn't restart until cool.  Appears to run at idle for roughly 15 minutes before stopping, a lesser time if being driven, or apparently until nearing operating temperature.

 

Various forums suggested fuel pump, or ignition switch, or various fuses or relays.  Changed fuses indicated as being part of fuel or ignition systems.  Same symptoms.  Changed some relays.  Same symptoms.  Changed electrical part of ignition switch.  Same symptoms.  Changed fuel pump.  Same symptoms. 

 

Problem appears to be related to some component warming - but which component?  Thoughts any one?

 

[Ahsai]

When it happens again, see if the tach needle bounces for about 1/8" or so when you are cranking. If not, it's likely the crank position sensor.

[Stefano Buganza]

Many years ago it happened to me because of a problem with an exhaust: when hot, it nearly closed, and car didnt start until cold. Hope this could help.

[Quadcammer]

crank sensor.

[Schnell Gelb]

On 10/22/2017 at 4:04 PM, Stefano Buganza said:

Many years ago it happened to me because of a problem with an exhaust: when hot, it nearly closed, and car didnt start until cold. Hope this could help.

This is actually a Catalytic Converter fault usually - not muffler/exhaust pipe. The 'brick' melts &/or gets plugged with carbon.