Fuel Pump Relay causing several cranks to turn over the engine, sometimes...

[tporter416]

Several months ago my 2007 A4 2.0T started having problems starting. Once running the car was fine, just would sometimes take several cranks to get it going. I verified the battery was good, so I started to see where the problem might be.

I found that if it did not turn over on the first crank, I would turn off the ignition and back on, if I heard the fuel pump, I would start the car. If not, turned it off and back to on again, repeat until I hear the fuel pump. The problem would disappear for a while, then come back so I decided to start by replacing the fuel pump relay. I purchased one from Audi, then found that actually replacing it is a PITA. I found a youtube video that showed howto remove the ECU, so I followed those instructions and replaced the fuel pump relay under the ECU.

The old relay looked ok, took it to work and we pulled it apart, still looks ok as the picture below shows. However when we cycled it, several times the relay did not close, no click....



My car has started fine ever since, and am fairly confident I have found the problem. I think the relay core is bad, but have not been able to find the actual reason for this relay to sometimes not close. I decided to post this here, so if anyone else has the same symptoms they can use this as a resource.

Thanks,

Tom

[phatjames167]

I occasionally also have a hard time starting my B& and will have to crank it a couple times or one long crank. Maybe I'll try this out, do you have a link to the YouTube video you used?

[tporter416]

Yes, the video is here: https://www.youtube.com/watch?v=kuTNPxHf_9c
It is done by a company that tunes B7 chips, you don't need to use a tool to remove the ECU security screws.
The relay is underneath the ECU, however the video is helpful, the relay is the first 614 you come across.

Tom

[Seerlah]

Relays just work by a magnetic field created by the wrapped wire (coil). If the relay would close only sometimes, then I would look into a resistance issue that makes the magnetic field not as strong to close the contact. Also be sure the flapper can move freely. Spraying it with electronic parts cleaner can probably fix it. Try that first and look for any corrosion or shorts.