Bleeding fuel system 2014 Jetta CJAA Need advice...

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rjsummer

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I just changed my fuel filter on my TDI (CJAA). I used VCDS to bleed it by running the fuel pump. I'm paranoid about having any air in the system, so I ran the VCDS which says its a 30 sec test. I just let it run and it switched off the pump automatically after 90 seconds. I did it a second time for a total of 3 minutes because the manual says 3 minutes when doing the pump.
So my question is this.... Is there any danger of harming the pump by running it "too" long? Can I damage or burn it out? Or is the 3 minute run a safe practice?

Referenced from the factory service manual...
"-Switch ignition on.
-Connect the Vehicle Diagnostic Tester and perform the "Vent Fuel System" Guided function.
-Note: the fuel pump is activated for 3 minutes.
-Then start the engine.
-After filling the fuel system, let the engine run at a moderate speed for a few minutes and then switch it off.
-Scan the DTC memory and delete the DTC memory entry if necessary.
- Test drive the vehicle for at least 20 km/h and test full-throttle acceleration at least once. Then check the high pressure area one more time for leaks."
 
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DrPeter

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Hello,

So my question is this.... Is there any danger of harming the pump by running it "too" long? Can I damage or burn it out? Or is the 3 minute run a safe practice?

- Good question, I would personally do what the repair manual says.

To the best of my knowledge, both of the electrical fuel pumps are running constantly in that vehicle.
This is done to maintain about 5-bar of fuel pressure to the High Pressure Pump when the engine is running.
So running for more than 3 minutes should be okay.

- Perhaps the manufacture knows that 3 minutes is more than enough time for a fuel system in proper working condition to fully prime.



ref:
G6 - Fuel system pressurization pump
"Delivers fuel constantly to the supply line"

V393 - Supplementary fuel pump
"Delivers the fuel from the supply line to the fuel pump"


We do have a Ross-Tech wiki page and video for the procedure: Fuel Pump Basic Settings for PD, PPD, and CR TDI Engines

- Just in case anyone did not see it or know :)



Hope this helps,

drpeter
 
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rjsummer

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Thanks for that information. The thing that had me really wondering is that it gives that procedure (3 min) as a conclusion to replacing the high pressure pump. (However, the filter change procedure says to bleed the fuel system with the VENT function, and refers to the same location as the one right after the pump replacement that I quoted) The filter change is less invasive, but then again, the filter change requires that the entire filter housing is emptied. I appreciate your insight, and think I should be ok to do that. (two 90 second runs) The car started up immediately and ran smoothly afterwards, I was just afraid to sustain any sort of wear damage, no matter how small, from not having enough fuel in the system.
 
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