Porsche Repair Questions? Ask a Mechanic for Answers ASAP
Hi, I am Mike, welcome. I'm reviewing your question.
How do you know the fuel supply is ok?
Ok, let me ask this then. When you first turn the key to run, can you hear the fuel pump run for a few seconds?
can you listen now or are you nowhere near the car?
The fuel pump is inside the fuel tank.
If the fuel pump doesn't run, check the fuse, so take a 30a fuse with you and the fuse is located in the fuse holder C behind the left kick panel.
If the fuse is ok, but the fuel pump still don't run and there are no security or check engine lights remaining on or flashing after turning the key on, then try a new fuel pump relay. If the fuel pump does, run, check the fuse/s for the fuel injectors and the ignition coils.
They are in this diagram, but they are the same fuse, the fuse C2 in that fuse holder C, and there is also a relay.
Yes, the fuel pump is located inside the fuel tank but the relay and fuse is not.
I would see if the engine will start up for a few seconds after spraying a few small shots of starting fluid into the throttle body. If it does, the ignition is fine, if not, then check the fuses for the ignition and check for a spark from the end of a spark plug wire. I like to use a new spark plug, open the gap up real wide like 0.075" so you can see it, attach a ground wire to it with a mini hose clamp and alligator clip, then remove a spark plug wire, plug this into the end of the spark plug wire then ground the alligator clip, and while cranking the engine over look for a spark.
Here is what my test plug looks like,
If it started and ran for a few seconds with starting fluid, then the ignition is fine, so it's probably the fuel system and if you say the fuel pump does run, then most likely the fuel injectors are not working. Since the fuel injectors are fed from the same fuse as the ignition coils, it must be that the injectors are not pulsing. Check the fuse for the engine control unit. They would be the fuse C1 in the fuse holder C.
I marked it,
From this point on you will need a noid light in order to check for a fuel injector pulse while cranking. If you don't have one, let's just assume there is no injector pulse then. Then you would need a scan tool in order to retrieve trouble codes to see if maybe the ECU isn't receiving a signal from a sensor before condemning the ECU itself.
It may retrieve any codes, try it.
It sounds like a security issue. Does the security or anti-theft light/message stay on or flash past bulb check, after about 10 seconds after the key is turned on?
Do you have a spare key you could try?
Are all of those still lit up after 10 seconds?
Did a spare key help?
Sorry, I was offline. But I think you should go back and confirm the fuel pump does run by removing the gas cap and putting your ear up to the gas tank gas cap hole and have someone else turn the key to run and listen if the fuel pump runs.