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Recommended Posts

Posted

Ok so my 04 Cayenne S idle was dipping when i stopped at stoplights, so saturday I swapped out the air filters and cleaned the throttle body.

I used carb cleaner sparingly on a clean rag. I cleaned it on the truck, I didn't remove it. So I was very un-intrusive.

It was running great the rest of the day, drove about 35 miles. Then Sunday morning, it started lugging, and dying. Fought for about 15 miles trying to get back home before it finally quit. Had it towed to my mechanic. He has reset the codes and unplugged the battery to no avail. Runs for about 30 seconds then dies. He said the fuel pump shuts off, then right when the motor is about to die it turns back on, sometimes in time to keep the engine running, sometimes not.

So now I have to have it towed to the dealer because he figures they will see codes his equipment doesn't.

Any ideas??

Posted

I believe you can test that yourself by unplugging the fuse for the primary pump, and then the system should switch to the secondary pump (they both are actually "primaries" IMHO - since they both provide full pump capabilities - just for their own side of the tank..) I did this test when I was seeking my balky starting problem. I first pulled one of the fuel pump fuses while the truck was running - it continued running. I replaced it, and took the other fuse out - the engine stopped (so that was the active pump). After cycling the ignition - the other pump (that I'd put the fuse back in for) was selected and the engine restarted.

Posted

I believe you can test that yourself by unplugging the fuse for the primary pump, and then the system should switch to the secondary pump (they both are actually "primaries" IMHO - since they both provide full pump capabilities - just for their own side of the tank..) I did this test when I was seeking my balky starting problem. I first pulled one of the fuel pump fuses while the truck was running - it continued running. I replaced it, and took the other fuse out - the engine stopped (so that was the active pump). After cycling the ignition - the other pump (that I'd put the fuse back in for) was selected and the engine restarted.

Slick, thanks. I'll update on the fix.

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