[egress91506]

Having some trouble with hot starts on my 99 Boxster. Car has been converted to a BSR. Past 2 weekends, I'd go out on the track, run a session (20-30 min), come off track, let it cool down and park it. Come back to the car later (15 minutes to an hour later) and it won't start. Engine cranks over, but no start. Eventually, after being left alone for a while (another 30 min, 1 hour), starts right up. Weather over the 2 weekends was high of mid-70s, low of 50s.

Tried troubleshooting a number of different things:

(1) engine cover off to let it cool down more, no impact. Vapor lock seems unlikely to me because have run the car in far hotter conditions without the problem. Also, vapor lock doesn't seem likely (in my uninformed opinion) because fuel returns to tank from fuel rails.

(2) swapped various relays (1 at a time) with working BSR. Fuel pump relay, DME relay, other related relays in back trunk of car. No impact, car wouldn't start with my switching in relays that were working in another car.

(3) pulled a coil pack off and confirmed the engine is getting spark. I think that eliminates the crank position sensor in this problem.

(4) plugged in the Porsche tester (PWIS?). No codes that would explain the non-starting. Code related to secondary air injection, but I always have that code on this car.

(5) key in first position, can hear the fuel pump running.

(6) opened up a fuel rail and fuel coming out. Porsche tech who was involved in troubleshooting didn't think the volume was what it should have been, so replaced the fuel pump. Didn't start after that until the waiting period was over. Following weekend, even with new fuel pump, still had the problem.

(7) no codes associated with the alarm box. My alarm box has been moved from the floor, so no chance of water damage. (Once the car was back to starting, I turned it off, unplugged the alarm box and turning the key would not engage the starter. Plugged it back in and it started. Since when I'm having the hot start problem, my car will engage the starter, but won't start, I concluded that the alarm box was not the problem. Flaw in that logic?)

(8) one other issue, which I noticed last Saturday was the fuel filler neck was filling with gas and slowly gurgling into tank. Don't think it's related, but don't want to leave out anything. By the way, used fuel from different places over the weekends, all real gas stations.

So, any ideas? Sorry for the long post and kudos to anyone who's read this far into it.