Fuel pumps & Fuse 14
08-02-2021, 02:12 AM
#1
Rennlist Member
Thread Starter
Fuel pumps & Fuse 14
Hi all,
2009 CTTS with 97K. So we took off on a family road trip today from Boise, Idaho to St. George, Utah to visit the in-laws. Then on to Lake Tahoe and back home in a week. All in all, it probably 1200 miles. South of Salt Lake City today, the car started shuttering, losing power, etc. Of course panic sets in, thinking transmission or something major. No CEL, so I pulled off, turn the car off (wishing and hoping...) but still there. I'm familiar with all 3 fuel pumps, since I replaced them all on my last Cayenne. I remembered reading about pulling a fuse to check. Sitting on the side of the road, I pulled fuse 14 and the car ran fine. We finished the 200 miles down to St. George. Now I have to figure out how to get this fixed. I've read some threads and possibly can do it myself or maybe a local shop but I've been thinking about this fuse 14 thing for 200 miles...
What exactly happens when fuse 14 is pulled? Does it shut off only 1 of the in-tank pumps? Or cut some sort of extra power layer? I'm assuming fuse 14 is only for the low pressure in-tank pumps? Having had issues with the HPFP on my last Cayenne, it was cutting out above 3500 rpms. This doesn't feel HPFP to me. By pulling this fuse, is it one pump that's bad (R or L) and is it easy to tell now? I'm thinking of just having the one changed, since I'm on a trip. I can change the other out at home when we return. Any quick help here would be appreciated. I'm going to try and find a scanner locally tomorrow in St. George but I'm sure there are no pumps in town so I'll have to order one in the morning so it will ship out. I'm puzzled how pulling a fuse can actually fix an issue. However, then leaving the fuse out isn't the solution. Crazy Germans
Cheers,
Travis
2009 CTTS with 97K. So we took off on a family road trip today from Boise, Idaho to St. George, Utah to visit the in-laws. Then on to Lake Tahoe and back home in a week. All in all, it probably 1200 miles. South of Salt Lake City today, the car started shuttering, losing power, etc. Of course panic sets in, thinking transmission or something major. No CEL, so I pulled off, turn the car off (wishing and hoping...) but still there. I'm familiar with all 3 fuel pumps, since I replaced them all on my last Cayenne. I remembered reading about pulling a fuse to check. Sitting on the side of the road, I pulled fuse 14 and the car ran fine. We finished the 200 miles down to St. George. Now I have to figure out how to get this fixed. I've read some threads and possibly can do it myself or maybe a local shop but I've been thinking about this fuse 14 thing for 200 miles...
What exactly happens when fuse 14 is pulled? Does it shut off only 1 of the in-tank pumps? Or cut some sort of extra power layer? I'm assuming fuse 14 is only for the low pressure in-tank pumps? Having had issues with the HPFP on my last Cayenne, it was cutting out above 3500 rpms. This doesn't feel HPFP to me. By pulling this fuse, is it one pump that's bad (R or L) and is it easy to tell now? I'm thinking of just having the one changed, since I'm on a trip. I can change the other out at home when we return. Any quick help here would be appreciated. I'm going to try and find a scanner locally tomorrow in St. George but I'm sure there are no pumps in town so I'll have to order one in the morning so it will ship out. I'm puzzled how pulling a fuse can actually fix an issue. However, then leaving the fuse out isn't the solution. Crazy Germans
Cheers,
Travis
08-02-2021, 10:53 AM
#2
Burning Brakes
@957GT-YES - you might want to follow along this thread as we are trying to clear up some similar questions:
https://rennlist.com/forums/cayenne-...etric-log.html
https://rennlist.com/forums/cayenne-...etric-log.html
08-02-2021, 11:09 AM
#3
Rennlist Member
Thread Starter
Thanks for the note. I'll check it out. It looks like you're going pretty deep. Mine seems to be different in the fact that I pulled fuse 14 and it seemed to solve the problem. In reading, it looks like fuse 14 goes to the right rear pump, so maybe I just need to replace that. I'll read yours as well to see if there is anything else I can glean from it. I'm going to scan the codes this morning and also talk with a local shop.
Cheers!
Cheers!
08-02-2021, 01:46 PM
#4
Rennlist Member
Thread Starter
Update: New info. Maybe someone can tell me if this sounds right... With no CEL, I stopped by the auto store and took a look anyway. Nope. No codes. I tried reading it with the 14 fuse in and 14 fuse out. I also pulled the 13 fuse with the 14 in and the car started and seemed to run the same. The car didn't seem to mind if the 13 or 14 fuse was out, it started, idled and climbed the rpms the same.
I had spoken with a super nice local mechanic (Fuzion, if you're in St. George) and although he didn't have time to look at it, he did walk through the scenario with me for about 10 minutes. He feels that the pump(s) are needing replaced at some point, but they are still functional and not dead. After running for 7-8 hours yesterday at 85-90 on cruise, they are getting hot and since I had about a 1/2 tank, they aren't cooling enough. I put both fuses back in after the scanner and the car has had zero issues for about 5-6 miles. I've hammered it a few times and the car still has the same amazing power as normal. I'm going to continue driving it around town and to Zion tomorrow morning before heading up to Tahoe on Thursday. I'd still like to get both in-tank pumps replaced locally, but I don't think I'll have time as everyone is booked up. Does this sound like a normal scenario where the pumps get hot and perhaps once cooled down they won't have an issue for awhile? I'll replace them once I get back to Boise, but maybe I won't have anymore issues?
Thanks.
I had spoken with a super nice local mechanic (Fuzion, if you're in St. George) and although he didn't have time to look at it, he did walk through the scenario with me for about 10 minutes. He feels that the pump(s) are needing replaced at some point, but they are still functional and not dead. After running for 7-8 hours yesterday at 85-90 on cruise, they are getting hot and since I had about a 1/2 tank, they aren't cooling enough. I put both fuses back in after the scanner and the car has had zero issues for about 5-6 miles. I've hammered it a few times and the car still has the same amazing power as normal. I'm going to continue driving it around town and to Zion tomorrow morning before heading up to Tahoe on Thursday. I'd still like to get both in-tank pumps replaced locally, but I don't think I'll have time as everyone is booked up. Does this sound like a normal scenario where the pumps get hot and perhaps once cooled down they won't have an issue for awhile? I'll replace them once I get back to Boise, but maybe I won't have anymore issues?
Thanks.