PorscheTX928

Endless: Did your Cayenne drive kind of crappy on the one pump? I took mine on the toll way today and it seemed to bog down over 3K RPMs. I had about half a tank of gas in it, but Im wondering now if the other pump might be going out too or perhaps the filter is clogged.

endless_corners

When I pulled fuse (14? or was it 13?) it made the truck drive normally. Previously it would stutter and hang and i'd floor it and then it would either die or burst into life and then die.. I could barely get it to my hotel. At which point I googled around and learned about the fuse thing. Opened the hood got my nickel out and open the fuse box. Pulled the fuse and oila back to normal. So for me it was a direct match.

ECS Tuning

FYI, the high pressure pump on the 957 V8 engines is on the back of the driver's side cylinder head, not in the tank. The procedure you are describing sounds like the in-tank pump replacement.

PorscheTX928

So you are telling me the Cayenne actually has three pumps in all? I might have called the Driver side pump incorrectly then. I am sure that the left pump in my Cayenne S is out as it does run SUPER crappy with both fuses in....and only semi crappy with fuse 14 out. For around town driving, it is fine, but at HWY/TOLL (80MPH+) it begins to bog down.

I was just going to go ahead and replace the fuel filter too....but since it is so easy to do, I think Ill just replace the pump and see if it fixes everything, or if it doesnt, it could mean these lifetime fuel filters might not be so lifetime as we thought.

geetee

2 low pressure pumps ...one under each rear seat. fuse 13/14 linked to these 2 pumps.
backside of valve cover on driver side is high pressure fuel pump (in engine bay) not related to fues 13/14
957's

geetee

fuel filter is not lifetime. These are sealed so youhave to change the fuel filter assembly. I cracked my old filter open and it was totally packed with crap at 110k miles
fuel filter assembly has to be reomved to get to the low pressure fuel pumps so most replaced them as well

endless_corners

I was like eff it. Not going to try and save a couple bucks up front only to tear everything open again. Replaced everything.

PorscheTX928

There are a few things Id do differently, but it was a pretty easy job. Here's where I am now. I didnt change out my pumps, they seemed to do fine, so I figured lets start with the fuel filter and since I will have to open the passenger side anyway to get to the attachment that goes from driver side to passenger, might as well do the regulator too.

3 important things you should do... 1) make sure you have no gas in vehicle if possible - I had been driving it so everyone said make sure you keep half a tank at least. 2) before you disconnect battery, make sure you pull 13/14 fuses, and cycle the engine a few times to relieve pressure, also undo gas cap. (I learned this the hard way with a spray of fuel to face) and lastly 3) double check all connections to make sure they are secure/locked (I had a hose pop off and was getting a no start issue...had to go back and found the loose connection on fuel filter - tank side!)

SO....how did I do? Well, the Cayenne started wonderfully, and on an initial drive did well, but after about 20 min, it would stall if you floored it...and suddenly thrust forward - ran crappy....I will admit it is running alot better, but definitely not fixed, yet. I can get easily back in to fuel filter and regulator because I left the bolts from seat belts off, so it is just the four 10mm bolts for plate, and Bam, I can be in gas tank in 5 min.

I cleared all codes before going out on test drive, and when I came back I had two codes....P1023 (Fuel high pressure too low during starting) and a P0660 (intake manifold timing valve control circuit open bank 1). I cleared them again and they have reappeared.

I did a forum search and found only one reference to the 1023 code which wasnt any help, and one reference to the P0660...which was by me!!! I asked about this code before and no one ever responded. :-(

If anyone has any idea of what this could be please help. Ive heard PCV valve and Venturi ventilation tube mentioned in similar posts, but I hate to throw parts at this issue.

If you have never changed out your fuel filter, Id recommend it...my filter had 85K miles and it is filled with dark grime....I cant believe Porsche says this is lifetime filter. I think it would probably need to be replaced every 40-50K from the condition mine was in.

PorscheTX928

I went out and tried the fuel pump tests and noticed something interesting as I was collecting data with my OBD tool. Whether or not you have the 13 or 14 fuse out, the reader was showing both pumps activated at startup. What Im not sure of is whether fuel pump 1 or 2 is the primary.

Fuse 14 (Left pump) out - started car, dies after 5-6 seconds (Reader shows both as active (1), but fuel pump 1 off almost instantly(0), then a few seconds later, car dies, then fuel pump 2 changes to (0).

With fuse 13(Right pump) out...car starts, and stays on. (Reader shows both active (1), fuel pump 1 changes to inactive (0), fuel pump 2 remains active (1).

What the heck? So if I disable left pump, car dies... disable right, the car stays on, fuel pump 2 shows active...this must mean pump 2 is the left pump, right? So, I have a bad pump 1....which is the right one.

I think im going to go with that logic and order the right pump...this is the first time I have seen the right one go bad on the boards...everyone seems to diagnose the main pump as the bad one.

Its late, so hopefully this all makes sense.

PorscheTX928

The saga continues. I ordered and received the right fuel pump today...or so I thought. It was very easy to get back in since I left seat belt brackets off from my FPR and Fuel filter replacement from early this week. When I went to put in the pump I noticed it was the wrong one. FCP Euro sent me the wrong pump (left). After they accepted blame, they graciously agreed to overnight the right pump and offered me the left pump at a discount. So, looks like my fuel system will be practically brand new after I get the right (right) pump. The left pump has been updated, so the PN is 95562093101. The right side pump is PN 95562093201.

Cost of parts:
FPR - 130.00
Fuel Filter - 90.00
Fuel Pump (L) - 200.00 with discount
Fuel Pump (R) - 229.00
Fuel pumps have lifetime warranty through FCPEuro.

After all that I have been through with the DIY project, I feel confident that I can answer any questions anyone might have regarding replacement of the FPR, fuel filter, or either fuel pump. I hope that my notes will help those in the future that undertake this project. My next project will be brake pads, as my warning light just went on for those.

Cheers

PorscheTX928

Ok...I am going to post here because no one is responding on the fuel pump diagram thread. I finally received the correct fuel pump this morning (long story), and went out to my dismantled Cayenne. I was a little concerned that there were so many hoses but everyone seemed to think it impossible to hook pumps up wrong.
Well, I must be the one knucklehead that could do it. I was hoping someone could tell me which connections I have incorrect. I cant seem to make sense out of the diagram for the fuel system. I got the idea to use my old parts to show my connections. The two white arrows are where I hooked up the sucking jet pumps (these were two identically sized male connections).

I put everything together, went out for a drive, and same things are wrong (long crank to start), no power when you go hard throttle. Both pumps are running(vibrations and humming), although my car scanner says pump 2 is not activating.

Here is a pic of my current configuration. Left side pump (filter on top), Right side pump (FPR on top).

stas101

Hi. I know its am old thread but were you able to figure out the problem?

PorscheTX928

Yes...I havent had that Cayenne for awhile now....but I did figure it out...turns out there is also a HPFP (high pressure fuel pump) mounted between engine and firewall towards the top....i was able to change it fairly easily with the correct socket wrench and extensions. Pump is pricey - 1K, but I found a used one on eBay from some European country I had never heard of for around 300.00 if I remember correctly. I changed it myself...I think others have paid 1800 to 2500 getting it done at an indie or the stealership.

Hope this helps.

stas101

Lol. Thx for reply. I know about HPFP that thing gave up on my in the summer and i changed it not hard to do just need a short 10mm wranch.I think my right side pump behind passanger seat is out now even though it only has less than 10k miles. I remove the fuse from drivers pump and car stalls after hard start in a few seconds. I remove the pass side pumps fuse and car starts fine and does not stall. I experience long cranking start and rough idle for a few seconds even though HPFP is new and high pressure is fine and stays on set point. Looks like pressure is just not steady on the low pressure rail.