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Hard Warm Start - 2

Engine

Model: 911, Year:1986, Mileage:100000, Type of use:Street use only
Hi Chris, I've tried the spark test that you suggested. I drove the car then parked and came back around 45 min's later and the fuel pressure was still at about 31psi. While I had someone else crank the car, I saw a bright blue spark on the plug that appeared to pulse every second, then after about 5 seconds the engine started and the spark was constant. I shut the engine off, waited a little while to trigger the issue again, and then repeated the test 2 more times with the same result each time. Is that spark pulse while cranking expected? If so, I assume this means the issue is fuel related?I have tried many times to press the gas pedal to the floor when expecting the hard start but it has never affected it. Other than maybe once it starts the engine revs high. I should mention that almost everytime this hard start issues happens, once the engine starts the revs will bounce a few times until it settles down at the proper idle. This idle bouncing is affected by the base A/F ratio. If I have the mixture richer it will bounce more times before settling down. Otherwise though, the idle never bounces and when starting the engine cold (after sitting for 12+ hours) or when starting back up quickly when hot, before the hard start issue is triggered, the idle never bounces and just goes straight the correct idle RPM.I recently posted a Youtube video of this hard warm start issue. Here the car had been sitting for nearly 3 hours and the engine was mostly cooled off and fuel pressure was gone. This was a "good" start but it still took nearly 5 seconds of cranking before it started and the idle bounced a few times too: http://youtu.be/MpbqQBhGeQQ

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