Couldn't find much online so figured I would share what I dealt with.
2012 Cayman S
. On cold start, car would run for 2-3 seconds, sputter and die. Started off doing it once or twice and over the course of 2-3 days, went up to 5-8 times. Once it would run, ran fine, no power loss at all and would not stall when driving or once warm. Now, keep in mind thru-out the diagnostic time, once we tried to start the car anywhere from 5-8 times (sometimes less) it would keep starting and we'd have to leave it overnight and start again in the morning.
Suspected high pressure fuel pump, but after testing it, it appeared to be holding proper pressure. Used
Autel
scan tool to confirm. Moved on to low pressure fuel pump, couldn't find a good place to check, so checked right from the sending unit, which involved removing the battery so used a battery booster pack. Just as the car started to stall, we lost low pressure fuel. Assumed it was the pump, but before ordering (from Germany!), decided to check voltage at the pump. As we lost low pressure fuel we lost voltage. Using a power probe, we could add power to the pump and when we did, the car kept running which likely ruled out the pump itself drawing too much power.
Thought it might be a relay issue, relay was cheap and readily available so just replaced it, but it made no difference. Checked the wiring diagram (from Mitchell/ProDemand), which showed the wire from the relay going straight to the fuel pump. We assumed there was a wiring issue, but the wire color from out of the relay, compared to what was going into the fuel pump was a different color.
Unsure at this point, I called the dealer to get a copy of the wiring diagram, but they would not share their wiring diagram with me, but did walk me thru it. From the relay, the wire goes to the Fuel Pump Control Module, which is right
next
to the pump, but under a separate piece of molding which you can't see unless you remove it. Checked the plugs and pins which all looked good. Couldn't find a way to test the actual module, but knowing how intermittent the problem was and how much a nightmare trying to chase the wiring to find an issue would be, decided to try to replace it. Part was also special order from Germany, but I was able to find a used one from a
911
, same part number, which could ship overnight. Ordered it, knowing it may need to be flashed to work. Once it arrived, we plugged it in, started it and ran fine. Tried 2 more times, each time ran normally. Swapped it back out for the old one, stalled. Tried again, stalled. Put the
911
one back it and it has been running normally since.
Very frustrating issue to diagnose, could not find much info at all, wiring diagram from ProDemand was wrong, but luckily got it figured out relatively cheaply. Hope this might help someone else down the road one day.
Thank you for sharing this info. I’m sure it will come in handy for someone else in the future.
