rmslay

I have an 09 Cayenne S with about 120K miles. About 2-3 months ago I noticed it took a bit more time to start once the starter began turning the motor over. When its cold it takes 2-3 seconds when it used to immediately fire up. When the motor is warm its not as bad. Also when it starts it sometimes runs pretty rough for 5-6 seconds before it smooths out. I didn't see any other threads on this so I was wondering if anyone had any suggestions.

thanks,
Richard

deilenberger

Search for a thread I started a LONG time ago about a similar problem. You may want to search using my username.

Chances are that one of the check valves in the fuel system has failed and your injection system is loosing residual pressure when the pumps shut down. It then takes the pumps a bit of time to pump up the system enough so the injectors have pressure.

In my case the dealers failed to diagnose the problem with the former owner (which is why he sold it) - I diagnosed it with a $29 Harbor Freight fuel-pressure test kit, and showed it to the dealer mechanics. It then took them 5 days to fix - eventually replacing everything pretty much in the fuel tank (turned out there is a undocumented check valve in the fuel filter that was causing the problem - and of course that was the last thing they checked.)

Rob VN

If you have access to a Durametric cable you can read the fuel pump(s) pressures. Look over at dorkphus where KMS987 documented his fuel pump replacement.

Good luck

rmslay

I went to Dorkiphus.net but can't find KMS987. Would you have a link?

-- never mind, found it. its 987kmns

bdtzmaru

Just to give you another perspective....

I went through this not too long ago. My 08 CTT would have a difficult time starting on the first try. I first replaced the battery, but it still would not start after the first flick of the key. Then I came across a post regarding the fuel filters and fuel pumps. I replaced those, with no luck in resolving the issue. My last resort was replacing the starter. After replacing the starter, the symptoms went away!

I dove right in and did the job myself and saved on labor. Thank goodness for DIY articles and threads! Not too bad on each replacement...it just takes time and patience. Good luck!

rmslay

I hooked up my Durametric cable but it won't read any actual values or even display any set values - on anything I select. I get "That selection is invalid for this vehicle" or something like that or ERROR in big red letters. Any suggestions?

deilenberger

Contact Durametic if it's a genuine Durametic cable. They provide excellent customer service.

deilenberger

I'll retract part of my statement above since the OP has an '09 with High-Pressure Fuel system. There may well be some sort of pressure sensor in that system.

Here is a direct link to the significant thread on the problem: http://dorkiphus.net/porsche/showthread.php?t=33294 Learn something every day..

kalyan

My 08 CS had the same issue few years ago. Dealer said there was a recall/TSB for the fuel pump. They kept the car overnight to see the problem for themselves. They replaced the fuel pump and I haven't had the issue again. I could be wrong, but I think there are two fuel pumps in these cars and I am not sure which one the dealer replaced. This repair was done under warranty.

Cheers,
-K

extanker

it does sound like a check valve and/or pump issue. are you sure it is cranking over normally ?as stated by others here the system can be tested to see if its holding psi.