Hesitant startup

So for about a month, my 06 cayman s has been hesitant to startup. It cranks just fine, and sounds normal, but it would often take about 10 seconds of cranking before it would actually fire up. This would happen on both warm and cold starts. One day, it was hesitant to start, and when it finally did, it sounded like it was running on 4 cylinders. I double checked to make sure I didn't trade it in for a 718 . It threw CELs for misfires on a few cylinders, but no other codes. It's always run great otherwise. I'm not sure where to look other than taking guesses. Could be fuel related, could be a cam or crank sensor, I suppose. But I don't have much to go on. Someone mentioned the Change-Over Diverter Valve Air Injection Control Valve (PN 7PP906270). Someone else mentioned the fuel tank pressure relief valve (PN E2014935029OES?) under the left side intake plenum. Any ideas?

I had this issue with my 2013 981 . It turned out to be a High Pressure Fuel pump . However, it was throwing a code in my case. Do 987's have two fuel pumps? One electric in the front and a mechanical on the engine for starting?

I'm not sure if the 987 has this. There's usually a check valve in the fuel system to keep the fuel lines to the injectors pressurized so the pump doesn't have to come up from zero pressure on start. When they get old they leak. Symptoms are a long crank while pressure builds. Don't think there's usually a code for it. If there is one it might be part of the pump. Take a look at PET. Should be a copy in the site files.

I would monitor fuel pressure at start up. There is a gauge port on the fuel rail near the air oil separator (RHS aft corner of engine compartment). If you belong to PCA you can get access to Cayman Register where there is an article on replacing the fuel pump . The delayed start was caused by a failing fuel pump in this case. YMMV. Good luck.

you might be getting small cracks in your coil packs, since it is a 2006 change your plugs and inspect the coil packs, very inexpensive first step.

I will add this on the possibility of losing fuel pressure as the cause of the problem. The next time you start the car after it has been sitting for quite a while turn the ignition switch to ON but don't start the car yet. Leave the ignition on for ten or fifteen seconds. After that turn the ignition switch the rest of the way and start the car. If it starts immediately the problem is probably a pressure leak in the fuel system. What this technique does is turn on the electric fuel pump and allow it to charge the system again before you start cranking the car. A bad check valve in the fuel line which is most likely in the fuel pump can cause this. A leaking fuel injector can cause the problem also. Another check is after the car has been driven and turned off immediately turn it on again. If if starts immediately that is an indication that the pressure hasn't had time to bleed off yet. That is assuming it is not a fast pressure leak. Most of these kind of problems are slow leaks and it takes quite some time to bleed off the fuel pressure enough to require extra cranking in order to get the car started.

@Midlifecrisis - Yeah, I was thinking along the same lines which is why I was leaning towards fuel. When i turn the key on, I don't hear the pump prime, unfortunately, and starting takes a long time as usual. But you're right, if I start it, turn it off, and immediately restart it, it will fire right up. So it's more than likely a fuel pressure issue.

If the pressure relief valve is built into the fuel pump , what fuel pumps will work for my 2006? The 2005-2008 pump?

Replaced the pump last night and so far it's firing right up.

@ circuiticon which pump did you replace ? is it the HIGH PRESSURE PUMP ? thank you