A8 Running Losing Fuel Pressure/ HELP
#1
06-05-2008, 07:44 AM
A8 Running Losing Fuel Pressure/ HELP
PLEASE RESPOND IF YOU HAVE ANY IDEAS,
I have a 1997 A8Q,4.2, with 130K on it. I have owned it for 2 months and have driven it for 4 days so far. On the 2ndday, it stalled and shut down throwing MAF codes and misfires. Replaced MAF, no start, found fuel pump to be bad, replaced pump (not assembly) as well as filter, fuel pump relay, and coolant temp sensor. I have good voltage at the pump, replaced o-ring on 2nd stage interconnect to resevoir and am sure it is installed properly and all hoses inside tank are good. Fuel pressure at rail is low. I found that the fuel pressure regulator has a slight leak and needs to be replaced.It's trickling fuel into intake. (MAF code from first stall. I have a good meter for sale!) Tank shows about 3/4 and then car shuts down. I top off the fuel tank and it runs again for about 100 miles and then stalls.I carry 5 gallons of fuel in the trunk to dump into make it toa gas station. I have seen similar posts here but never see a final resolution to the problem after it is fixed. Could the fuel pressure regulator leak cause the ECU to shut down the fuel pump if it max's out it's trim range? The new fuel pump (Siemens VDO) does not have the 6mm nipple on the pump end like the stock pump motor. This nipple plugs into the 2nd stage pump line within the fuel pump assembly. Of course the source for the pump told me that they sent the correct pump. I haven't been able to find one with the additional suction nipple and feel sure it is necessary. Someone, please provide some input. I could just give it to the dealership and end up in a rape crisis center. The Audi shop I took it to last week wanted to replace the fuel pump assembly and regulator.($1100) I told them I was confident the pump was good but they said all they were willing to do was replace the whole thing. The car wasn't running and I told them I will try to fix it myself. I paid for their expert diagnosis (I gave them a full page write up of what I had done and all of the symptoms, they spit the info right back to me) and towing. I said I would get a gas can and put 5 gallons in it and drive it home and they responded that I was crazy and it wouldn't work. I beeped and waved as I drove out of their lot. Been keeping the can in the trunk (full) for a week now. Give me you thoughts and theories. I love my car and hate being afraid to drive it. One good thing.......more seat time on the Aprilia.
I have a 1997 A8Q,4.2, with 130K on it. I have owned it for 2 months and have driven it for 4 days so far. On the 2ndday, it stalled and shut down throwing MAF codes and misfires. Replaced MAF, no start, found fuel pump to be bad, replaced pump (not assembly) as well as filter, fuel pump relay, and coolant temp sensor. I have good voltage at the pump, replaced o-ring on 2nd stage interconnect to resevoir and am sure it is installed properly and all hoses inside tank are good. Fuel pressure at rail is low. I found that the fuel pressure regulator has a slight leak and needs to be replaced.It's trickling fuel into intake. (MAF code from first stall. I have a good meter for sale!) Tank shows about 3/4 and then car shuts down. I top off the fuel tank and it runs again for about 100 miles and then stalls.I carry 5 gallons of fuel in the trunk to dump into make it toa gas station. I have seen similar posts here but never see a final resolution to the problem after it is fixed. Could the fuel pressure regulator leak cause the ECU to shut down the fuel pump if it max's out it's trim range? The new fuel pump (Siemens VDO) does not have the 6mm nipple on the pump end like the stock pump motor. This nipple plugs into the 2nd stage pump line within the fuel pump assembly. Of course the source for the pump told me that they sent the correct pump. I haven't been able to find one with the additional suction nipple and feel sure it is necessary. Someone, please provide some input. I could just give it to the dealership and end up in a rape crisis center. The Audi shop I took it to last week wanted to replace the fuel pump assembly and regulator.($1100) I told them I was confident the pump was good but they said all they were willing to do was replace the whole thing. The car wasn't running and I told them I will try to fix it myself. I paid for their expert diagnosis (I gave them a full page write up of what I had done and all of the symptoms, they spit the info right back to me) and towing. I said I would get a gas can and put 5 gallons in it and drive it home and they responded that I was crazy and it wouldn't work. I beeped and waved as I drove out of their lot. Been keeping the can in the trunk (full) for a week now. Give me you thoughts and theories. I love my car and hate being afraid to drive it. One good thing.......more seat time on the Aprilia.
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