Fuel filter replacement

**Andrew Turner** · 14-04-2019,05:21 PM

Do you need VCDS to prime the fuel system? Does it not self prime when you start the engine?

**Gmonster** · 14-04-2019,07:15 PM

Good query; I too am interested in the Answer. I am due a fuel filter change and want to do it myself. Have purchased a Mann Fuel filter... and I am familiar with the filter location and access arrangements. Is it a straightforward swap over and turn over engine to start...etc? .... 2.0 TDi C7 etc.

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**H8t0w8** · 14-04-2019,10:28 PM

I have used my odbeleven to run the pump to prime the system. Didn't want to run the risk.
You could try just cycling the ignition untill your satisfied it's primed.

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**B5NUT** · 14-04-2019,11:09 PM

If you go by the manual you should prime the system, however Audi dealers never bother and just turn the engine over.

**philipharmes** · 15-04-2019,10:34 AM

Cycling the ignition does nothing on the CR engines.

The pumps only run when cranking the engine & when running.

So either make sure you fill the filter fully then crank ( risk damage to the HPFP ) or use VCDS to prime it. ( Best option )

**Gmonster** · 15-04-2019,11:19 AM

Not really wanting to take any risks with this. I have obdeleven.... Is the ‘run fuel pump/prime’ function fairly straightforward/easy to find/use?

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**KevTrem** · 15-04-2019,12:38 PM

Originally Posted by Gmonster

Not really wanting to take any risks with this. I have obdeleven.... Is the ‘run fuel pump/prime’ function fairly straightforward/easy to find/use?

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From memory go to

CONTROL UNITS
ENGINE
FUEL SYSTEM
FUEL PUMP
You then have option to prime the pump, you'll hear the air as the system purges. I did the prime function twice just to be sure, it runs the pump for between 1 and 2 mins.

**Gmonster** · 15-04-2019,12:39 PM

Cheers will have a look.

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**bluezie** · 16-04-2019,02:09 PM

When I did mine on the 3.0V6, I started the engine, and it ran perfectly with no missfires or stumbles.
So the pump appears to be able to cope with an air filter's worth of air, fire it back down the return, and not get any in the high pressure circuit.
The must be a chamber that the HP pump draws from the bottom, the air rises to the top and exits via the return line.