fuel pump/s on 2005 porsche cayenne

[MarkPlu]

my 2005 Porsche has started having problems starting everytime I remove the fuel cap to fill up.  It still starts ok otherwise, I haven't noticed really any other problems with it.  My guess is it is probably the boost fuel pump for starting.  Please advise your thoughts.  If this is the case I am thinking probably better to change both pumps anyways as they as still original and if I am going to be there anyways thinking better to get both then go back in in another couple months.  also being there is the filter easily accessable at the point of pulling the pumps out and if so would you recommend replacing that/those as well not sure how many filters are there.  is there anything else i should get for this job as in a special seal or something? not sure if anything will be destroyed.

 

[Brainz006]

You need to replace the purge valve for the evap system. It's about $100 part, if I recall, and isn't terribly difficult to replace. It's located to the right of the throttle body when looking from the front of the engine bay. The hardest part is the connection at the back of the engine - - the rubber hose will be stuck tight. Search is your friend. It's a valve with a 2 foot long plastic pipe that runs under the plastic valve cover cap.

In the interim, to get the engine started after filling up, hold down the gas pedal to the floor and it will start quicker until you replace the valve.

You can also use a soft rubber vacuum cap with a tiny hole drilled in it (0.5mm) to choke the amount of vacuum allowed through the valve. This will make the car start w/o issue and is a cheap [temporary] fix. If it throws a code, the hole is too small, if it still is hard to start the hole is too big. The cap can easily be installed on the intake side valve nipple, and then reinstall the rubber intake hose over both the cap and nipple. While this fix will work, the car will generally eun more smoothly if you just replace the valve.



Sent from my Nexus 6 using Tapatalk

[MarkPlu]

I will do that first. Sounds fairly quick and cheaper than pumps and filters.  Thanks for the advice.

[MarkPlu]

about to order part, since right there should i replace plugs and coils too? not sure what coils are for but see it on the lists?

 

[Brainz006]

There is a small amount of overlap with doing the purge valve and with plugs and coils. But probably only 10 mins overlap.

If the condition of the plugs is unknown, it's relatively cheap to replace them and takes about 2 hours, most of which is spent on the right side of the engine). But if the car is running fine (no rough idle, no hiccups or stuttering under acceleration, no codes) then you might not want to mess with it until you notice an issue (or run up a bunch of miles that would otherwise warrant a change). Don't fix it if it's not broken.

Coils definitely matter, and can cause problems, but given their expense, I personally won't replace them unless they're visually cracked, are throwing a code on a cylinder, or I've already exhausted all other suspects (namely vacuum leaks, including the purge valve). My recent experience also suggests that stuttering under acceleration can also be coils.

Doing the plugs is a good way to check for cracked coils. Top tip: if you find any that are cracked whilst doing the plugs, reinstall the cracked coils on the left-hand cylinder bank and mark them with a paint pen. That way you can order replacements and quickly swap them, as the left side is much easier/faster to work on than the left side - - probably less than a half hour the second time around.

Good luck.

Sent from my Nexus 6 using Tapatalk