Quick Cal

Im working on my Sons 2000 A6 4.2 Quattro. He took it apart 3 years ago for a timing belt change and did not finish it. Now I am putting it back together.

I don't know if any of this is important, but thought I better give a state of affairs in case I am missing something obvious.

He had put the wrong power steering fluid in. So he had me suck out what I could with the intensions of flushing the system. But that job is not finished. So Just to be able to start the car I left the accessory belt of so it would not turn the pump. So the covers and all that is left off.

Car will not start. We thought just because of old gas. Now I have determined it's due to lack of fuel. But it will start on starting fluid and seems to run fine.

I dropped the fuel filter and nothing is getting pumped by the fuel pump. The fuse is good and the relay clicks when I take it out and put 12v to it. But the pump that is under the rear seat is not powering up. BTW. Is there more than one pump on this car. I am getting 7.8v at the fuel pump harness when cranking it over. Is this voltage too low to energize the pump. Or is the pump bad. Again. Is there more than one pump in this car as I have read about on slightly different models. Thanks

Quick Cal

Hmm. Don't see how to edit post.

Anyway. I just thought of something. Is there some kind of sensor in the front of the car that will shut off the fuel pump in case of an accident. As I said earlier, the car is not put back together. The front bumper is off. I wonder if I have something unplugged that needs to be plugged in. Maybe that's why I'm only getting 7.8v to the pump. And assuming the pump need 12v to work. Or should it work on 7.8v and that is a normal reading.

I also want to show where I was getting the 7.8v. From the green/yellow and brown. Also 7.8v from purple and brown.

georgeb944

Charge your battery. Running the car without the alternator (driven by the serp belt) has probably run down the battery.

If you are then still getting less than 12 volts at the fuel pump, replace the fuel pump relay. There have been instances of high resistance in the contacts causing weird fuel problems.

If that doesn't work, time to pull out the VCDS and pull all the codes and report.

Quick Cal

I have charged the battery, and also jumped it while trying to start it. The only time the car has run is for a very short time off of starting fluid.


But you do have me thinking. I'm not sure if the battery was fully charged, or I had it hooked up to jumper cables when I checked the voltage. I'll have to try again,,,lol.

Quick Cal

Could I just throw 12v to the fuel pump to see if it comes on.

If so, would the green/yellow wire be ground and the brown wire be positive??

georgeb944

According to the wiring diagram, green/yellow is +12vdc and brown is ground.

Quick Cal

Thanks!

maelove

I don't know if you've figured this out yet. But if not, I'll tell you what I know about the fuel pump system.

Alright, so if you want to know if the fuel pump is bad, do this: jump the relay. Remove the relay, and (with the car off), take a piece of wire (I stripped the plastic off a USB cable) and stick it into the two slots that are "30" and "87". 30 will be your ground. When you do this, your fuel pump will start priming. You should be able to hear it. Keep it priming for a little bit, and try starting. If it does start, the pump is bad. If it doesn't, then the pump may still be bad, but could also be 100 other things. You could also use a multimeter to test the resistance between 86 and T. As a rule of thumb, resistance under 50 ohms = bad relay. Here are a few pictures including when I replaced my pump (I have the same make and modle as you)

maelove

Oh, and in regards to your power steering problem, the proper PS fluid is CHF 11S for our cars. It's part mineral oil, part hydraulic fluid. If he's driven the car with the wrong fluid, then lets hope there wasn't too much damage. Other wise, just remove a line that returns the PS fluid to the reservoir and start the car. Then add the CHF 11S to flush out the rest of the wrong one, and fill the reservoir up. That's how I'd do it anyways. Any other way involves removing the pump.

So, can you answer a question of mine? I've never removed the vicious fan yet (mechanical). Is the fan clutch a 32mm? How did you get yours off?

Quick Cal

Thanks for all the info.

It's a 32mm. But it's been 3 years since we took it off. I don't remember what we did,,,lol. I think I read it was reverse threads though. Not sure though.