2009 Cayenne GTS fuel pump problems
I have an 09 Cayenne GTS I use to drive across the desert to the eastern Sierras. I had a
problem with the fuel pump cutting out at level driving speeds. Once the speed dropped
6-10 mph while I was giving it gas, the second acceleration fuel pump would kick in and I
could accelerate back to normal speed but once I leveled off it started the cycle again,
which lasts about 20 seconds. Try driving 300 miles like this! Porsche could not find any
code problems but went ahead and replaced the fuel pump. It is now happening again,
especially when the temperature outside is 100 degrees or so. Help! Anybody experience
this before? Thanks
Actually sounds like vapor lock. Have you changed brands or grade of fuel recently? -Jim
It does sound like vapor lock, as Jim said. You can try insulating your fuel lines, especially on top of the engine with foam made for pipes, and then wrapping in foil. Other than that, you might have to re-route the lines further from the engine heat. Use caution when re-routing lines, you don't want a car fire.
I have the same problem with a 2008. I was driving across Kansas yesterday in 80 degree weather. I was averaging about 90 mph. The engine light came on and the car would cut out briefly about every 30 to 60 seconds. I could maintain about 75 mph and would drop only a few mph each time. I could not use cruise control. I had about 1/4 tank of fuel. I stopped at a gas station and filled it up and never had another problem. I had the same problem 2 years ago and Porsche replaced the fuel pump. When it happened a few months later, they could not figure it out and refused to replace the fuel pump again. I don't think they believed me, even with the codes saying I had a fuel problem. It has not happened since but this is the first long trip I have taken since then.
Sure sounds like vapor lock. You could try mounting an oil cooler away from the engine and run the fuel from the back of the car to the cooler and back to the rails, keeping all lines as far as possible from the engine. Use gas line only, preferably braided, double clamped or A/N fittings. Insulate the lines with foam. Safety first. This should work, but be careful. Good luck.
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