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I have a 2005 Cayenne with about 65K miles. Just recently and only randomly the car has had a hard time starting. When I turn the key the sound of the starter is coming but it just doesn't fire up. After a few attempts it starts and the last time it happened I pushed on the gas pedal and that got it to start.

Do you think it could be a fuel pump problem? Anyone have similar issues?

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Best to check all the fuses as I believe you have two fuel pumps. Could be a fuel pump problem. Have you had the battery load tested? A weak battery can exhibit all sorts of odd problems in these vehicles.

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I have an '05 turbo with 73k miles and recently i have noticed it is a little slower to kick off. I haven't had the problems to near your extent of having to crank for way long period or play with the gas pedal. I just noticed instead of it start on the first or second turnover it takes a couple more. Let me know if you find out your problem as mine could potientally be heading that route.

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I checked the fuses and they are all good. I also checked the battery under load and its good. I went to a PCA club meeting at a dealership and asked their tech, he right away said most likely a fuel pump issue and its hard to replace since its under the rear seat on drivers side and you have to remove so many things.

How do I confirm if its a fuel pump and how do I replace this, anyone have experience. In the past 3 weeks the car has started perfectly every day except for 3 times where it tried to start but didn't.

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The car is equipped with 2 fuel pumps, in the morning at first start, when you grab the outside door handle to open the door, one fuel pump should run for a sort time to pre load the injection system and to perform an easy start. In the fuse/connector/relay box, situated under the black plastic (grill) trim in front of the driver side wiper, you will find 2 fuel pump fuses and 2 fuel pump relays (1x pump 1 1x pump 2). Remove both relays, ignition on, make a bridge between pin 30 and 87 alternately between pump 1 and pump 2, the pump which doesn't run is defective. Open the rear doors and pull up the rear seats to check this out (the pumps are situated left and right side under the rear seats) It could be the left one.

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My owners manual doesn't list any fuel pump relays, can you confirm from the picture if the part labeled 433 is it, is the other smaller one 404 for the second fuel pump?

post-24974-1242154220_thumb.jpg

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ROW cars have mini relays, look if 404 is a double relay, a wiring diagram should help a lot because the owner's manual is only intended as a kind of first aid and not for more significant problems.

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Thanks for the diagram.

Ok I have located the relays, now how do I make a bridge and to what pins? How will I know if the pump is working, will it make some sound? When when you say fuel pump relay - right, is this the drivers side?

Relay 19 is the fuel pump relay - right

Relay 1/6 is the fuel pump relay - left

post-24974-1242160863_thumb.jpg

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Terminals 3 and 5 with a fused jumper, you should be able to hear the pump run.

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If the pumps do run by jumpering the 3 and 5 terminals, check that the relays are actually serviceable as well by applying correct voltage between pins 1 and 2 and confirming continuity between pins 3 and 5 with a multimeter.

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I checked both the fuel pumps today by removing the relays and then supplying 12volt power to the correct points. I heard the fuel pumps go on. I then checked the relays by supplying power to pins 1 and 2, and they both clicked, there was continuity in 3 and 5.

I guess everything is alright here, perhaps there is something else wrong with the car. Any Ideas?

On a separate note, While I was working on the car I attached a durametric and found the following codes, my engine light also went on today. I don't think this is related to the starting issue above so maybe I need to start a new tread now.

P0117 Engine Coolant Temperature Circuit (Short to Ground or Positive)

P3081 Engine Coolant Temperature Circuit (Short to Ground or Positive)

If the pumps do run by jumpering the 3 and 5 terminals, check that the relays are actually serviceable as well by applying correct voltage between pins 1 and 2 and confirming continuity between pins 3 and 5 with a multimeter.

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Good to see that the relays and pumps are serviceable.

I would suggest that you also confirm that both the relay mounting bases (car side) also have the correct voltage and ground to actuate the relays when the pumps should be running.

Edited by bigbuzuki

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Erase the codes and take a look if they come back after a test drive, it has something to do with the temp. sensor or wiring.

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It has been a week or so since I cleared the code and today they came back.

P0117 Engine Coolant Temperature Circuit (Short to Ground or Positive)

P3081 Engine Coolant Temperature Circuit (Short to Ground or Positive)

Also I had a hard time starting today, it took a few attempts before the car started. Can anyone guide me to how to resolve these code issues, where should I look.

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You need to replace the coolant temp sensor, the part has been updated.

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Ok thanks, do you have a diagram that shows where the coolant temp sensor is so I can replace it and also the part number.

Edited by 97boxsterred

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Hi,

can someone tell me where the thermostat housing is located on a v6 cayenne. I am trying to replace the coolant temp sensor but can't find where it's located. The picture I have of the part diagram is no help, I need to physically find the part in the engine bay first.

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97boxsterred

The thermostat housing, inclusive temperature sensor is located on the rear/left of the engine (V6).

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I was unable to locate where the temp sensor is, I tried looking everywhere including where you mentioned. Do you know which parts I have to remove to get to the location of the temp sensor? If you can provide some instructions that would be great. I have a 2005 v6 cayenne.

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From above: remove the engine top cover - use a mirror between the fire wall and the left rear side of the engine.

On a lift: easier to look at the sensor, left side on top of the bell housing. If you have basketball player arms you can work on it from there, if not, use the first option.

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RFM:

The good news is that I finally located the temperature sensor. When you said left rear side of engine from above, I assumed it was the passenger side. However the temperature sensor is on the driver side. The location is just terrible, rear of the engine near the firewall, very tight and impossible to work on. Just follow the large pipe water coolant pipe out of the front radiator towards the back of the engine and it turns into this temperature housing location.

I took out the pin holding the sensor and all the coolant leaked out. Now its impossible to get the pin back in since the space is so tight. When I finally do manage to get it in, is there anything I need to do about the coolant to make sure no air gets trapped in there. How do I properly refill the coolant again.

Thanks

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Just fill up the coolant tank till the top, Cayenne's gives no problems with air bubbles or what ever.

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