1999 A8 THE AUDI DEALER AND NEW FUELPUMP
05-19-2013, 01:16 AM
#11
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Well where do I start. About 4 months ago the fuel pump went in our 1999 Audi a8. I brought the car to the dealer and $1500 dollars later we were running again.
Now 4 months later the car shuts off at a half a tank. So I bring the car back to the dealer and they tell me that there are Auxiliary pumps inside the tank that pump the fuel to the main pump and one of those is probably bad and it will be very costly to figure out.
The mechanic tells me just don't let it run under a 1/2 a tank.
From what I read I think their feeding me a line. Whats your oppinons?
Now 4 months later the car shuts off at a half a tank. So I bring the car back to the dealer and they tell me that there are Auxiliary pumps inside the tank that pump the fuel to the main pump and one of those is probably bad and it will be very costly to figure out.
The mechanic tells me just don't let it run under a 1/2 a tank.
From what I read I think their feeding me a line. Whats your oppinons?
I have a friend who is having the same 1/2 tank issue and says the aluminum gasket with the immbedded seal is whats causing air to get into the system and starve under half tank of gas.
10-18-2014, 10:37 AM
#12
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I had the same problem, but now it's fixed...and I'm not sure how.
After giving up on it for 6 months and driving with 2 extra gallons in the trunk for 6 months... I tried to troubleshoot it again, but the problem seemed to have fixed itself somehow.
Initially, whenever I tightened that long bolt, air would come back in the return line and the engine would sputter. By loosening the bolt and breaking the seal between the two halves of the pump assembly, most of the tank would gravity feed to the pump...allowing use of about 2/3 of the tank volume.
Six months later I re-visited the issue... and could not reproduce the problem. I tightened down the bolt, and everything ran fine. I even ran the tank down to empty with an indicated 0 miles remaining, and still no problem.
Maybe air gets into those in-tank tubes and it needs to work itself out. Or maybe you just have to tighten and re-tighten that long bolt until it seats properly.
I've put about 2000 miles on it now...and ran it near empty several times. I did not need to replace any seals... and I did not need to pull out the assembly. I just tightened down the bolt again (maybe the 12th attempt) and the problem was gone.
So...I don't have the exact answer, but I thought maybe my experience might help in some way.
After giving up on it for 6 months and driving with 2 extra gallons in the trunk for 6 months... I tried to troubleshoot it again, but the problem seemed to have fixed itself somehow.
Initially, whenever I tightened that long bolt, air would come back in the return line and the engine would sputter. By loosening the bolt and breaking the seal between the two halves of the pump assembly, most of the tank would gravity feed to the pump...allowing use of about 2/3 of the tank volume.
Six months later I re-visited the issue... and could not reproduce the problem. I tightened down the bolt, and everything ran fine. I even ran the tank down to empty with an indicated 0 miles remaining, and still no problem.
Maybe air gets into those in-tank tubes and it needs to work itself out. Or maybe you just have to tighten and re-tighten that long bolt until it seats properly.
I've put about 2000 miles on it now...and ran it near empty several times. I did not need to replace any seals... and I did not need to pull out the assembly. I just tightened down the bolt again (maybe the 12th attempt) and the problem was gone.
So...I don't have the exact answer, but I thought maybe my experience might help in some way.
Here it is, a month later, and after reading your post, I thought I'd give it a try. I loosened the long bolt and re-tightened it... Nothing. So then I disconnected the electrical connector and tried starting it. Just as before, it seemed to want to start, but wouldn't. After 3 or 4 times of loosing and tightening the bolt, as well as disconnecting the fuel pump electrical connector, it finally started!!
It only ran for about 30 seconds before sputtering out again, so I decided to loosen the bolt again and try starting. FINALLY, I was able to get it started and running!! I gave it some RPM's, and it seems just fine.
This all happened today. Hesitantly, I drove it to the gas station and put more fuel in the car... No issues so far. I came back home and decided to tighten the fuel pump bolt, and then drove it down the road, and again, no issues.
I'm not sure this is a permanent fix, but hopefully long enough to get the money together to get the pump replaced... If, of course, that is even the problem. Any advice would be very appreciated!
10-18-2014, 02:00 PM
#13
AudiWorld Senior Member
I had a similar problem last year on my 2000 A8. INDY installed new pump. EXPENSIVE. Bottom line, I asked for the old pump, took it home. (My wife has a 99 A8). I found a video showing how to remove the actual pump motor inside with a new one.
I got the pump (very specific about the part number) and installed it inside the big plastic thing, wrapped it in a plastic bag and put it on shelf. I even took the old pump motor apart to see for myself what was wrong. Sure enough the little brushes were half gone and the stator (slotted thing where the brushes contact to make it turn) worn way down. This verified for me that I really did have a bad pump.
Now the "rebuilt" pump is sitting on the shelf and I"m thinking of selling it. Of course, I'm not advertising it here in the forum because I should put it in the classifieds.
I got the pump (very specific about the part number) and installed it inside the big plastic thing, wrapped it in a plastic bag and put it on shelf. I even took the old pump motor apart to see for myself what was wrong. Sure enough the little brushes were half gone and the stator (slotted thing where the brushes contact to make it turn) worn way down. This verified for me that I really did have a bad pump.
Now the "rebuilt" pump is sitting on the shelf and I"m thinking of selling it. Of course, I'm not advertising it here in the forum because I should put it in the classifieds.
10-20-2014, 03:32 PM
#14
AudiWorld Senior Member
Imagine trying to commence sexual intercourse, in the dark, absent physical sensation, with a squirming partner, and without looking or using your hands to aid alignment. That in essence is the problem with installing the fuel pump in a D2 Audi A8.
Jesus, there is so much bad information and misinformation around about this stupid fuel pump. I've had to cut one out...60,000 miles ago .... on my own car which has been trouble free ever since and did another one for a friend with no issues whatsoever in about an hour and a half which included pumping out the tank with the new pump to test if it was seated properly. When I cut mine out due to a spinning captive nut, I removed EVERYTHING from inside the tank, epoxied the captive nut then reinstalled it.
The tank is shaped like a saddlebag. It's lowest parts are far forward on either side of the car. Inside the tank there is a cup with a couple of pick-up hoses going to the lowest parts of the tank. Think of it like a spider - the cup is the body and the hoses are the legs. The fuel pump sucks fuel in 2 ways: 1) from the cup up through the fuel line to the injectors; and 2) from the hoses inside the tank to constantly re-fill the cup inside the tank. All of the bad install problems arise from this second part not working.
The fuel pump assembly drops into this cup which is NOT at the lowest point in the tank. On the side of the cup there is a female suction port that mates to a corresponding male suction port on the pump assembly. It is this connection that feeds function "2" above - from the remote hoses (spider legs) to the cup (body). When these two are misaligned, the pump still works, but you only get gas to the injectors while the cup assembly is submerged in gas. So long as your cup is submerged - say 1/3 or 2/5 a tank of gas - you are fine. The cup, remember, is not at the lowest part of the tank. Also, the cup is not well-secured inside the tank, rather the hoses attached to it are clipped to the bottom of the tank, so it has a little bit of wiggle room.
The big retaining ring at the top of the tank holds the fuel pump assembly securely in place. The foot long bolt that passes through it secures the cup inside the tank to the bottom of the fuel pump assembly. The problem is, you can get this sucker to bolt up even when the male/female suction ports miss each other entirely. This connection powers function 2. This is the sex in the dark problem, you tried, but missed the hole. So if it is re-installed but quits at one third tank, here is what you need to do:
1) loosen the bolt partially..say just about under an inch, then loosen the BIG ring securing the pump assembly.
2) now lift up on the assembly and give the bolt head a whack on top until it drops down. There, you have now separated the cup from the assembly. Now remove the bolt entirely.
3) Lift your *** up, aim your member first, then drop down. If you drop down first, then try to align, you'll miss the hole and bump up beside it, rather than drop down into it. In fuel pump parlence, this means hold the assembly as high up as you can...maybe just an inch or so... as you rotate it clockwise toward the alignment marks. ONLY lower it when you cannot rotate it. FIRST you want to rotate clockwise into alignment, and only THEN do you drive it down. tighten bolt...leave the big ring off for now until you pump out the tank.
4) Replace the banjo fitting with a threaded fuel barb...6 feet of cheap fuel line...pop the cover off the FP relay in passengers footwell...push contacts closed with a piece of cardboard or whatever, switch ignition on and pump out the tank completely. Switch ignition on/ off to pump out tank. If it doesn't empty completely, loosen bolt partially and re-do steps 2 & 3. If repeated attempts fail, remove assembly entirely, reach down inside tank and give the cup assembly a little counterclockwise twist. Try again.
Not rocket science, just sex in the dark.
Jesus, there is so much bad information and misinformation around about this stupid fuel pump. I've had to cut one out...60,000 miles ago .... on my own car which has been trouble free ever since and did another one for a friend with no issues whatsoever in about an hour and a half which included pumping out the tank with the new pump to test if it was seated properly. When I cut mine out due to a spinning captive nut, I removed EVERYTHING from inside the tank, epoxied the captive nut then reinstalled it.
The tank is shaped like a saddlebag. It's lowest parts are far forward on either side of the car. Inside the tank there is a cup with a couple of pick-up hoses going to the lowest parts of the tank. Think of it like a spider - the cup is the body and the hoses are the legs. The fuel pump sucks fuel in 2 ways: 1) from the cup up through the fuel line to the injectors; and 2) from the hoses inside the tank to constantly re-fill the cup inside the tank. All of the bad install problems arise from this second part not working.
The fuel pump assembly drops into this cup which is NOT at the lowest point in the tank. On the side of the cup there is a female suction port that mates to a corresponding male suction port on the pump assembly. It is this connection that feeds function "2" above - from the remote hoses (spider legs) to the cup (body). When these two are misaligned, the pump still works, but you only get gas to the injectors while the cup assembly is submerged in gas. So long as your cup is submerged - say 1/3 or 2/5 a tank of gas - you are fine. The cup, remember, is not at the lowest part of the tank. Also, the cup is not well-secured inside the tank, rather the hoses attached to it are clipped to the bottom of the tank, so it has a little bit of wiggle room.
The big retaining ring at the top of the tank holds the fuel pump assembly securely in place. The foot long bolt that passes through it secures the cup inside the tank to the bottom of the fuel pump assembly. The problem is, you can get this sucker to bolt up even when the male/female suction ports miss each other entirely. This connection powers function 2. This is the sex in the dark problem, you tried, but missed the hole. So if it is re-installed but quits at one third tank, here is what you need to do:
1) loosen the bolt partially..say just about under an inch, then loosen the BIG ring securing the pump assembly.
2) now lift up on the assembly and give the bolt head a whack on top until it drops down. There, you have now separated the cup from the assembly. Now remove the bolt entirely.
3) Lift your *** up, aim your member first, then drop down. If you drop down first, then try to align, you'll miss the hole and bump up beside it, rather than drop down into it. In fuel pump parlence, this means hold the assembly as high up as you can...maybe just an inch or so... as you rotate it clockwise toward the alignment marks. ONLY lower it when you cannot rotate it. FIRST you want to rotate clockwise into alignment, and only THEN do you drive it down. tighten bolt...leave the big ring off for now until you pump out the tank.
4) Replace the banjo fitting with a threaded fuel barb...6 feet of cheap fuel line...pop the cover off the FP relay in passengers footwell...push contacts closed with a piece of cardboard or whatever, switch ignition on and pump out the tank completely. Switch ignition on/ off to pump out tank. If it doesn't empty completely, loosen bolt partially and re-do steps 2 & 3. If repeated attempts fail, remove assembly entirely, reach down inside tank and give the cup assembly a little counterclockwise twist. Try again.
Not rocket science, just sex in the dark.
Last edited by BrianC72gt; 10-20-2014 at 06:26 PM.
10-21-2014, 01:56 AM
#15
AudiWorld Member
I changed the actual pump within the assembly on my old D2, followed these instructio
<iframe width="640" height="480" src="//www.youtube.com/embed/rgOUgUm2JpY?rel=0" frameborder="0" allowfullscreen></iframe>
<iframe width="640" height="480" src="//www.youtube.com/embed/no5K_Ri6xBA?rel=0" frameborder="0" allowfullscreen></iframe>
It worked just fine.
<iframe width="640" height="480" src="//www.youtube.com/embed/no5K_Ri6xBA?rel=0" frameborder="0" allowfullscreen></iframe>
It worked just fine.
Last edited by A 8; 10-22-2014 at 10:55 AM.
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