Fuel Filter Change_CJAA. Do I need a VAG-COM?

UberVW_TDI · Jul 23, 2010

I'm almost at 20k miles (18.5k) so I will be installing a new fuel filter soon.
While researching I've found two places stating that the CBEA and CJAA engines will not cycle the aux fuel pump by turning the ignition to on (to prime the new fuel filter).

I've found two articles stating that I'm going to need to use a VAG-COM to purge the air out of the fuel canister

http://www.myturbodiesel.com/1000q/a5/2009-2010-VW-TDI-fuel-filter.htm

http://www.tdiblog.com/tdi-do-it-yourself/replacing-fuel-filter-a5-brm-cbea/

From link above: "On my 2010 Jetta, (CJAA) the lift pump does not cycle with the key. I suspect that it does not on do so on the 2009 (CBEA) either. I have to use VCDS to do a test to fill the canister."

Anyone change there fuel filter on a 2009+ TDI? Do I need to use a VAG-COM to activate the aux fuel pump?

Thanks!

JSWTDI09 · Jul 23, 2010

My Bentley manual states (for CBEA, and CJAA engines):

"Any time the diesel fuel system is opened or drained for repairs, prime the system before running the high pressure fuel pump. Running the pump dry causes damage"

It does not say it MAY cause damage - it says it causes damage. I think that spells it out pretty clearly. Therefore, Yes, you do need Vag-Com (or the official VW scan tool).

Have Fun!

Don

DoctorDawg · Jul 24, 2010

Your alternatives (in descending order of goodness) are:
1. Drain housing, install filter, prime with VCDS - this is what God intended.
2. Or, drain housing, install filter, refill housing with fuel after changing filter.
3. Or, never empty the filter housing in the first place; just plunge new filter into housing full of dirty old diesel
4. Or, drain, replace, then sit there all day cycling the key between on and off with nothing happening.
5. Or, after draining the filter housing put in a new, dry filter, screw the lid back on, and just crank it till it starts...if it ever does...which it prolly won't.

Anything lower than #2 on this list is a bad idea in so many ways.

sabersix · Jul 24, 2010

JSWTDI09 said:
My Bentley manual states (for CBEA, and CJAA engines):

"Any time the diesel fuel system is opened or drained for repairs, prime the system before running the high pressure fuel pump. Running the pump dry causes damage"

It does not say it MAY cause damage - it says it causes damage. I think that spells it out pretty clearly. Therefore, Yes, you do need Vag-Com (or the official VW scan tool).

Have Fun!

Don

What section of the manual did you find this quote? In the fuel system teardown or in the scheduled maintenance?

I can understand that opening the fuel system (i.e. high pressure injection equipment) would require priming. I don't believe it is necessary to prime the system with a VCDS after "servicing" the low pressure fuel filter equipment. If you drain the filter housing, then fill it up after you change the filter. There is not going to be any air introduced into the system from the low pressure side unless it is run completely dry which isn't going to happen with a simple fuel filter service.

T_D_I_POWER · Jul 24, 2010

You should not cycle the FP off-&-on to fill the FF, doing so it'll eventually damage the FP and ignition. It's better to fill the FF with Diesel fuel manually using a funnel with filter inside the FFH. Leave room ~1/4"-1/2" from the top so no fuel spillage when FFH cover plate is mounted back on.

JSWTDI09 · Jul 24, 2010

sabersix said:
What section of the manual did you find this quote? In the fuel system teardown or in the scheduled maintenance?

I can understand that opening the fuel system (i.e. high pressure injection equipment) would require priming. I don't believe it is necessary to prime the system with a VCDS after "servicing" the low pressure fuel filter equipment. If you drain the filter housing, then fill it up after you change the filter. There is not going to be any air introduced into the system from the low pressure side unless it is run completely dry which isn't going to happen with a simple fuel filter service.

Section 20-20, Fuel Storage and supply. (in the paper manual)

The low pressure side is the source of fuel (oil) for the HPFP. I have no plans to argue either way, I just quoted the manual. You can take it any way you want.

In the CD version of the manual (I have both), in the section on replacing the fuel filter, when it tells you how to install the new filter the final step is "Fuel System, Filling". This is the same priming instructions as the paper manual.
1) select Engine controller
2) select 04 basic setting function
3) enter 35 and confirm
4) press activate
5) run pumps for at least 60 seconds
6) repeat 3 times
7) start engine, let run at moderate speed for a few miuntes, then stop and check for leaks
8) erase any DTCs
9) perform a road test longer than 20km where accelerator is pressed down completely at least once, then check for leaks again.

If there is air in the system the car may go into "limp mode". Stop engine and clear DTC codes and repeat test drive until system is fully bled.

This is the"official" procedure. How necessary it is, is debatable; but I will follow it, not debate it.

Have Fun!

Don

sabersix · Jul 24, 2010

JSWTDI09 said:
Section 20-20, Fuel Storage and supply. (in the paper manual)

The low pressure side is the source of fuel (oil) for the HPFP. I have no plans to argue either way, I just quoted the manual. You can take it any way you want.

In the CD version of the manual (I have both), in the section on replacing the fuel filter, when it tells you how to install the new filter the final step is "Fuel System, Filling". This is the same priming instructions as the paper manual.
1) select Engine controller
2) select 04 basic setting function
3) enter 35 and confirm
4) press activate
5) run pumps for at least 60 seconds
6) repeat 3 times
7) start engine, let run at moderate speed for a few miuntes, then stop and check for leaks
8) erase any DTCs
9) perform a road test longer than 20km where accelerator is pressed down completely at least once, then check for leaks again.

If there is air in the system the car may go into "limp mode". Stop engine and clear DTC codes and repeat test drive until system is fully bled.

This is the"official" procedure. How necessary it is, is debatable; but I will follow it, not debate it.

Have Fun!

Don

Well that is pretty clear. Thanks for taking the time to copy all that in here.

UberVW_TDI · Jul 24, 2010

Thanks for the replys.

It is strange that the Bentley manual doesn't reference to section 20-20 in the "03-31 fuel filter, replacing" procedure. The last steps in section 03-31 simply says

Place upper filter housing with new seal on lower filter housing.
Tighten bolts to specification in diagonal sequence.
Install upper sound absorber panel
Start engine and check for leaks.

I will be using the VAG-COM method. Thanks again!

Hurricane Drew · Nov 4, 2011

Sorry to dig up and old thread, but I was shocked to notice this wasn't mentioned as well in the 03-31 section. That's probably as far as many people will look.

740GLE · Nov 4, 2011

i've survived 2 filter changes myself by prefilling no VCDS, and started each time (with some good luck key cycling to boot)

btcost · Nov 4, 2011

I helped to write the tdiblog version

It's my Father's car being used.

We need to update that to recommend using vagcom, and if not available cycle the key.

Funny it seems the 09-10's will prime the pump when you cycle the key. I need to test my '12 out. . .

The #1 recommended way is: remove/drain canister for proper cleaning with lint free rags and or brake cleaner (leave proper time for brake cleaner to dry after use)

new filter, fill with your favorite Power Service like product or diesel, prime with key/vagcom, start car

n1das · Nov 4, 2011

JSWTDI09 said:
Section 20-20, Fuel Storage and supply. (in the paper manual)

The low pressure side is the source of fuel (oil) for the HPFP. I have no plans to argue either way, I just quoted the manual. You can take it any way you want.

In the CD version of the manual (I have both), in the section on replacing the fuel filter, when it tells you how to install the new filter the final step is "Fuel System, Filling". This is the same priming instructions as the paper manual.
1) select Engine controller
2) select 04 basic setting function
3) enter 35 and confirm
4) press activate
5) run pumps for at least 60 seconds
6) repeat 3 times
7) start engine, let run at moderate speed for a few miuntes, then stop and check for leaks
8) erase any DTCs
9) perform a road test longer than 20km where accelerator is pressed down completely at least once, then check for leaks again.

If there is air in the system the car may go into "limp mode". Stop engine and clear DTC codes and repeat test drive until system is fully bled.

This is the"official" procedure. How necessary it is, is debatable; but I will follow it, not debate it.

Have Fun!

Don

I followed the procedure when I did my FF changes (2 done so far) on my 2010 JSW. No metal found in the FF housing during both changes. No problems starting up after each FF change.

What bugs me is I wonder if VW dealer service techs are following the factory procedure to the letter when doing a FF change during "free" maintenance. My gut feeling is they may change the filter and fill the canister but not go thru the priming procedure. If the car stalls from lack of fuel, I suspect they simply dry crank it until it starts

again, like they are notorious for doing with older TDIs.

I suspect (incompetent) VW dealer service may be causing some of the HPFP failures that weren't caused by gasoline contamination or bad fuel.

dsldubb · Nov 5, 2011

btcost said:
<snip> (leave proper time for brake cleaner to dry after use)<snip>

Go to a local CAT dealer and get the Low VOC Brake Cleaner. That stuff dries sooo quick. And it will turn grease into water. Stuffs strong. And leaves no residue.

cristoaca · Nov 9, 2011

As am close to 20k miles, I stopped the dealer today and asked the service advisor and a tech about priming using the VCDS. The SA said no VCDS, just filling up the canister with diesel. Worse, the tech said they don't prime it at all because "it just picks up by itself". Will definitely not use their service.

740GLE · Nov 10, 2011

I don't think anyone here has posted a failure of th HPFP that can be directly related to someone not priming they system properly.

A few members have had theirs stall after not priming, then cranked away until it caught, I don't think they've reported back they had a failure. I could be mistaken but i don't think priming is a big of a deal as everyone thinks it is, granted its the 100% CYA method.

n1das · Nov 10, 2011

cristoaca said:
As am close to 20k miles, I stopped the dealer today and asked the service advisor and a tech about priming using the VCDS. The SA said no VCDS, just filling up the canister with diesel. Worse, the tech said they don't prime it at all because "it just picks up by itself". Will definitely not use their service.

That more or less confirms my gut feeling and why I choose to DIY instead of letting a VW dealer service department touch it. The FACTORY procedure(s) given in the Bentley manual are NOT being followed.

I used the writeup on myturbodiesel.com (www.myturbodiesel.com) for my FF changes since I don't have the Bentley manual yet. The writeup I used is the same procedure given in the Bentley manual.

maxedtdi · Nov 10, 2011

Can someone explain the difference in "priming" and running the engine to me. In essence you're doing the exact same thing.

When you "prime" you are essentially running one of the pumps without fuel as well.

I don't see a valid scientific explanation for this esp when it comes to damaging the pump. The only reason most "prime" a fuel system is so that the car doesn't have to crank excessively after a fuel filter change. And so that you have enough fuel in the engine itself.

n1das · Nov 10, 2011

maxedtdi said:
Can someone explain the difference in "priming" and running the engine to me. In essence you're doing the exact same thing.

When you "prime" you are essentially running one of the pumps without fuel as well.

I don't see a valid scientific explanation for this esp when it comes to damaging the pump. The only reason most "prime" a fuel system is so that the car doesn't have to crank excessively after a fuel filter change. And so that you have enough fuel in the engine itself.

Dry-cranking is BAD to do and is to be avoided at all costs since the fuel system including HPFP is lubricated entirely by fuel.

The engine is not started during the priming procedure. The VCDS procedure manually operates the two electric pumps one at a time to make sure there is only fuel and not air going thru each pump.

The first pump operated during the procedure is the in-tank lift pump. This pump is buried in fuel so there's no danger of this pump running dry unless the tank is empty (out of fuel). After running this pump for a minute, the auxilliary electric pump on the engine is run for a minute or two push fuel thru the filter to engine's HPFP. Now that we have nothing but fuel all the way to the HPFP, it is now safe to start the engine and not risk the HPFP running dry of fuel.

STRANGETDI · Nov 10, 2011

btcost said:
I helped to write the tdiblog version

We need to update that to recommend using vagcom, and if not available cycle the key.

Funny it seems the 09-10's will prime the pump when you cycle the key. I need to test my '12 out. . .

The #1 recommended way is: remove/drain canister for proper cleaning with lint free rags and or brake cleaner (leave proper time for brake cleaner to dry after use)

new filter, fill with your favorite Power Service like product or diesel, prime with key/vagcom, start car

How do you prime with the key vs. prime with VCDS? I guess I am not understanding fully. BTW, I just got my 2012 last week.

JSWTDI09 · Nov 10, 2011

STRANGETDI said:
How do you prime with the key vs. prime with VCDS? I guess I am not understanding fully. BTW, I just got my 2012 last week.

You don't prime with the key. I do not think that priming with the key works at all with the newer (CR) diesel engines. When I turn on my key, I do not hear any fuel pumps running. When I use VCDS, I can hear them both running. Therefore, I cannot (will not) ever recommend turning the key on and off as a way to prime the fuel system. It just doesn't work anymore. This used to work on older TDIs, but it does not seem to work at all on the newer ones. If you do not have VCDS, find someone who does to help you. IMHO, It is the only safe way to ensure that there is fuel to the HPFP before you crank the engine.

If you insist on changing the fuel filter without VCDS - make sure you fill the fuel filter canister with fresh diesel fuel before you put the cover on. This is at least better than leaving it empty.

Have Fun!

Don

sflier · Nov 10, 2011

740GLE said:
I don't think anyone here has posted a failure of th HPFP that can be directly related to someone not priming they system properly.

A few members have had theirs stall after not priming, then cranked away until it caught, I don't think they've reported back they had a failure. I could be mistaken but i don't think priming is a big of a deal as everyone thinks it is, granted its the 100% CYA method.

Here's someone who did have a HPFP within a relatively short period after performing their filter change without priming using VCDS. Read post #1 and #8. There is no evidence that not priming the system using the official method contributed to this failure, but it seems very coincidental and circumstantial enough for me. I'll follow the proper procedure and use VCDS to prime mine:

http://forums.tdiclub.com/showthread.php?t=333967

dsldubb · Nov 10, 2011

maxedtdi said:
Can someone explain the difference in "priming" and running the engine to me. In essence you're doing the exact same thing.

When you "prime" you are essentially running one of the pumps without fuel as well.

I don't see a valid scientific explanation for this esp when it comes to damaging the pump. The only reason most "prime" a fuel system is so that the car doesn't have to crank excessively after a fuel filter change. And so that you have enough fuel in the engine itself.

You're priming the system to get fuel in / air out of the HPFP. The only time the HPFP is pumping is when the engine is running. Also priming doens't put fuel in the engine itself. That's called hydrolocking.

Ever since the MKIV's VW has had the pump prime when the drivers side door is opened. And it only does it if the car has been sitting for a while. Not sure what the cutoff is before it primes again. When you get to your car this afternoon, listen for the pump as soon as you open your door. It only comes on for a few seconds, 3-5 sec I think. This is because most people don't turn the ignition on and wait for a couple seconds before cranking. Most people stick the key in and crank right away.

Most knowledgeable diesel owners wait for the glow plugs so for some of you on here might not fall into that category, but like i said, MOST people do.

dsldubb · Nov 10, 2011

sflier said:
Here's someone who did have a HPFP within a relatively short period after performing their filter change without priming using VCDS. Read the very first post. There is no evidence that not priming the system using the official method contributed to this failure, but it seems very coincidental and circumstantial enough for me. I'll follow the proper procedure and use VCDS to prime mine:

http://forums.tdiclub.com/showthread.php?t=333967

The first post said he filled up... nothing about changing filter...

sflier · Nov 10, 2011

I meant to look at post #8 where he said he did his 40k service himself, without using VCDS. And I could be wrong but I thought only the 2.0 TSI primes when the door opens. My wife's Tiguan primes when the door opens if left for a while but I've never heard my TDI make a sound.

mpriolo · Nov 10, 2011

I change the fuel filter every 10K miles along with the oil filter change. Been doing that since 40K and I now have 70K on the tdi (no problems so far). I simply remove the old filter and "press" in a new filter. The engine turns over immediately without any cranking needed.

The filters come out pretty clean, so I don't think the fuel left in the FFH is appreciably more dirty than what is in the fuel tank. Also, when you press in a new filter, the o-rings are extremely tight on the black cylinder in the center of the FFH. The only way I can see that the fuel can get to the cylinder is to go back through the filter material. In pushing the filter into the FFH, you need to go slowly (letting the filter absorb the fuel) or else you'll wind up with a face full of fuel.

So, I am not seeing how leaving "old" fuel in the FFH can cause a problem. If I am missing something, I'd appreciate your comments.

Thanks,

Marty

sgoldste01 · Nov 11, 2011

dsldubb said:
Ever since the MKIV's VW has had the pump prime when the drivers side door is opened. And it only does it if the car has been sitting for a while. Not sure what the cutoff is before it primes again. When you get to your car this afternoon, listen for the pump as soon as you open your door. It only comes on for a few seconds, 3-5 sec I think.

I listened for the pump prime this AM when I opened my driver's door, after the car had been sitting unused in my garage for 3 days. I didn't hear anything.

tcp_ip_dude · Nov 11, 2011

dsldubb said:
[snip..]
Ever since the MKIV's VW has had the pump prime when the drivers side door is opened. [..snip]

This is not the case on '09 and newer CR TDI's. Confirmed using VCDS/VAG-Com.

BarnyardsTDI · Nov 11, 2011

UberVWTDI, do you per chance work at Samsung Austin Semiconductor?

n1das · Nov 11, 2011

tcp_ip_dude said:
This is not the case on '09 and newer CR TDI's. Confirmed using VCDS/VAG-Com.

Also the same with PD TDIs (Mk4IV and MkV) and older VE TDIs (MkIII and MkIV) which don't have a lift pump in the tank.

Ever since the MKIV's VW has had the pump prime when the drivers side door is opened. And it only does it if the car has been sitting for a while. Not sure what the cutoff is before it primes again. When you get to your car this afternoon, listen for the pump as soon as you open your door. It only comes on for a few seconds, 3-5 sec I think.

Must be a gasser thing if there's any truth to it at all. It's an urban myth with TDIs. It's along the same line as the glowplugs supposedly operate when the driver's door is opened.

dsldubb · Nov 11, 2011

Yea I am only certain regarding the door open priming with gassers. (1.8T, and 24v). Any proof that the pumps prime in the TDIs with ignition on? I doubt it very much.

Fuel Filter Change_CJAA. Do I need a VAG-COM?

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