Box runs for 20mins then dies - 986 Forum - The Community for Porsche Boxster & Cayman Owners

Kyle2112 · 03-30-2014, 05:02 PM

Hello group, I’m looking for a little help with this problem. A week ago I drove the Boxster 16 miles and when I stopped at the light it died. Pushed the car to the side of the road and tried to restart and no luck. After trying a few more times the battery went dead. I’ve been meaning to replace the battery anyways so I got a tow home and just for the heck of it I had the tow’er jump the car and it started right up. I replaced the battery and drove it to work (5mins away) and no problems. It was idling a little rough so I cleaned the throttle body. I started it up let it run for about 10 mins or so and then took it out for a spin. Ran great the throttle was more responsive and no hunting idle. I pulled up to the stop sign and it died. I walked home and came back two hours later. It started right up and I drove it home. In the driveway it will do the same thing. Start it up , run for twenty mins then just die. I took the alternator out today and had it checked and all tests pass. It has not thrown any codes. I’m attaching a snapshot of the last 15mins of the car running right before it died. Anyone got any ideas? Thanks in advance.

Steve Tinker · 03-31-2014, 12:53 AM

This could possibly be:
1) The crank position sensor (CPS) which fails when hot.....enter CPS in the search function and read on.
2) Fuel pump failure - you'll need a fuel pressure guage to check.
3) Sometimes MAF failure can cause hot start problems - remove MAF and see if the car starts.

kk2002s · 03-31-2014, 03:56 AM

I had exactly same symptoms. It was my Fuel pump relay. (Cheap fix)
You can do a search on how to trouble shoot. After running then dying, you can feel how hot the relay gets
Thought it might be fuel pump but started trouble shooting at relay first and fortunately that was it

dghii · 03-31-2014, 10:20 AM

+1 on fuel pump relay. There is another relay in the fuse box that is identical to the FP relay (can't recall which one right off the top of my head). Swap them out and go for a drive!

Kyle2112 · 03-31-2014, 07:17 PM

Thanks guys, I'll try the relay. I ran it tonight and it did get warm. I didn't have time to make a jumper and test it. Thanks again.