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2000 A6 2.7 crank no start

 
Old 02-11-2019, 03:47 PM
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Default 2000 A6 2.7 crank no start

I'm on a long-haul epic-style diagnosis with my 2000 A6 Quattro 2.7 with tiptronic. The car is sitting at my house, and the engine will crank but not start. I don't hear any firing, either. There's no power on either fuse (#28 and 29, I believe) when the key is turned to the ON position. I've confirmed that the timing belt didn't break by opening the passenger side cover and eyeballing the belt while the engine was cranked. The battery was replaced within a week of the initial failure. About a week before the battery was replaced, there were two failed engine start attempts because the old battery didn't have enough CCA. At each of those failed start attempts, the engine started after getting a jump from another car's battery.

I've recently subcribed to alldatadiy.com to get the wiring diagrams, but I'm still stumped why the fuel pump relay is not engaging with the ignition key at the ON position. I pulled the fuel pump relay (#273?) and tested it good with a voltmeter while connecting the correct leads (#30 & T?) directly to the battery terminals.

Help?
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Old 02-11-2019, 03:51 PM
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A couple more notes: I replaced the passenger side camshaft position sensor twice after the failed start, once with a used one, and again with a new one. While cranking the engine, I read about 320RPM on my OBD scanner's live data.
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Old 02-12-2019, 04:19 AM
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I'm pretty sure that the fuel pump relay is picked by the ECU once it figures out that it is getting a good signal from the crank sensor. It does not pick with just the ignition key turned on. My guess is the crank position sensor.

Of course, I could be wrong, I'm not a professional.
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Old 02-12-2019, 05:56 AM
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Also it might be good to check the connections to the coils.
Maybe that would stop the ECU from turning fuel pump on .

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Old 02-12-2019, 06:04 AM
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It is my understanding if the revs show on your tester when you are cranking then the crank position sensor is functioning. Is there anything you might have overlooked or not reconnected when you did the cam sensor?
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Old 02-13-2019, 10:50 AM
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I had a mysterious no-start crank on my '99 2.8L and I was about to tow it to my (Audi specific) mechanic - he asked me when I had changed the spark plugs (it had been at least 50,000 miles). Before towing he said "CHANGE THE PLUGS"... so, 6 NGK's later I started the car - fired right up. So....if you don't know the age of your plugs, or it's been 40,000+, give that a shot.
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Old 02-24-2019, 01:42 PM
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A huge thank-you to all who replied. I diagnosed the fuel pump as faulty by the following steps:

- disconnected battery
- disconnected ECM
- pulled rear seat and disconnected wiring
- jumped pin 63 to ground
- connected battery
- tested for full battery voltage at fuel pump connector under rear seat

I replaced the fuel pump after siphoning out over 14 gallons from the trunk access port. The alldatadiy.com subscription was worth every penny, although it took me some chair time to internalize it all. Another big shout-out to the fuel-pump replacement write-up. I don't have a link at the moment, but will dig for anyone who asks. I ended up fabricating the pump assembly install/removal tool from a few feet of 5/16" steel bar stock from the local home improvement store, a 4.5" diameter PVC pipe, and an angle grinder.

I did order the following parts on suggestion; their installation is scheduled pending more accommodating weather:

- spark plugs
- camshaft position sensors
- crankshaft position sensor / engine speed sensor

Again, thanks to all for the encouragement!
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Old 04-30-2019, 03:16 PM
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Originally Posted by jorg0370 View Post
A huge thank-you to all who replied. I diagnosed the fuel pump as faulty by the following steps:

- disconnected battery
- disconnected ECM
- pulled rear seat and disconnected wiring
- jumped pin 63 to ground
- connected battery
- tested for full battery voltage at fuel pump connector under rear seat

I replaced the fuel pump after siphoning out over 14 gallons from the trunk access port. The alldatadiy.com subscription was worth every penny, although it took me some chair time to internalize it all. Another big shout-out to the fuel-pump replacement write-up. I don't have a link at the moment, but will dig for anyone who asks. I ended up fabricating the pump assembly install/removal tool from a few feet of 5/16" steel bar stock from the local home improvement store, a 4.5" diameter PVC pipe, and an angle grinder.

I did order the following parts on suggestion; their installation is scheduled pending more accommodating weather:

- spark plugs
- camshaft position sensors
- crankshaft position sensor / engine speed sensor

Again, thanks to all for the encouragement!
Am I reading this correctly that the issue was a bad fuel pump? I am having a very similar problem. I would not expect a bad fuel pump to cause the fuel pump relay to not activate?
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Old 04-30-2019, 08:07 PM
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Yes, my root problem was a bad fuel pump. I don't remember much about the relay other than I pulled and tested it.
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