Fill up volume of 2012 Passat TDI

Flyboy777 · Apr 14, 2016

Ok, I I'm new to the Diesal world but am a bit baffled. When I fill up my Passat it only shows 7/8 full with the fuel RIGHT up to the cap. Granted I do a fast fill then after the click off I slowly top it off. I have heard that Diesal foams SIGNIFICANTLY on a fast fill. I'll have to try a slow fill next time I fill up (which is NOT all that often!) as far as a refill with the range showing < 10 KM remaining I can only get in AT MOST 63 Litres in what is supposedly a 70 litre tank. Granted I expected VW to build in a bit of a reserve into the zero range mark so I would expect there to be 50 or a 100 km of fuel left in the tank at 0 range. SO that amounts to about 5 Litres. I'm just a bit stumped as 6 or 8 litres would take me probly 150 km so I'm thinking part of this is just due to fuel foaming and the other part is the reserve. I like to get to know my vehicle and my last one I knew how much fuel I had in tank when the fuel low level came on and how close to E I REALLY WAS when the needle hit the bottom of "E". Any experience out there with this? Just how tolerant are these fuel delivery systems to Burping? ie sucking air. Old school diesels fuel systems I have heard through the grapevine need bleeding but I have no Idea how these modern high pressure injection engines tolerate air ingestion. I have read that the fuel system needs purging when changing fuel filters by running two pumps via plug in software or manually jumping the pumps ..... Sounds like a pain in the ass. Yet others say just top off the canister really well and no problems ..... Just start er up. Thoughts? I'm thinking of doing my own fuel filter changes but don't want to fry the hp pump. All for saving a few bucks on a filter change.

TheGrove · Apr 14, 2016

Yes this is a known issue, there are some threads in this forum about it I just can't put my fingers on them right now. As memory serves it has to do with the shape of the tank and where the fuel level is taken.

You DO NOT want to suck air. When that happens the car will stop and will not restart without bleeding the air out of the injector rail. Your best bet is when you get to the low fuel warning to plan on filling. At this point you will have about 1.5 gallons or so in the tank.

Many of us recommend not running your tank that low. One reason is that it will start to pick up any contamination that may be in your tank and can cause problems. Another reason is that the fuel pumps cool themselves with the "cold" fuel from the tank. When your tank gets low this fuel gets warmer due to the fuel being returned from the injectors which has been heated due to the high pressure it was put under.

You should be able to do your own changes. You will need to prime the filter before starting, I believe there are 2 ways you can do this. First would be to fill the filter with fuel after replacement. The 2nd is to use a VCDS program and there is supposed to be a setting you can use to turn on the fuel pump to fill the filter.

Hope this helps, I'm sure others will chime in with recommendations and corrections.

TheGrove · Apr 14, 2016

Yes this is a known issue, there are some threads in this forum about it I just can't put my fingers on them right now. As memory serves it has to do with the shape of the tank and where the fuel level is taken.

You DO NOT want to suck air. When that happens the car will stop and will not restart without bleeding the air out of the injector rail. Your best bet is when you get to the low fuel warning to plan on filling. At this point you will have about 1.5 gallons or so in the tank.

Many of us recommend not running your tank that low. One reason is that it will start to pick up any contamination that may be in your tank and can cause problems. Another reason is that the fuel pumps cool themselves with the "cold" fuel from the tank. When your tank gets low this fuel gets warmer due to the fuel being returned from the injectors which has been heated due to the high pressure it was put under.

You should be able to do your own changes. You will need to prime the filter before starting, I believe there are 2 ways you can do this. First would be to fill the filter with fuel after replacement. The 2nd is to use a VCDS program and there is supposed to be a setting you can use to turn on the fuel pump to fill the filter.

Hope this helps, I'm sure others will chime in with recommendations and corrections.

South Coast Guy · Apr 14, 2016

Flyboy777 said:
Ok, I I'm new to the Diesal world but am a bit baffled. When I fill up my Passat it only shows 7/8 full with the fuel RIGHT up to the cap. Granted I do a fast fill then after the click off I slowly top it off. I have heard that Diesal foams SIGNIFICANTLY on a fast fill. I'll have to try a slow fill next time I fill up (which is NOT all that often!) as far as a refill with the range showing < 10 KM remaining I can only get in AT MOST 63 Litres in what is supposedly a 70 litre tank. Granted I expected VW to build in a bit of a reserve into the zero range mark so I would expect there to be 50 or a 100 km of fuel left in the tank at 0 range. SO that amounts to about 5 Litres. I'm just a bit stumped as 6 or 8 litres would take me probly 150 km so I'm thinking part of this is just due to fuel foaming and the other part is the reserve. I like to get to know my vehicle and my last one I knew how much fuel I had in tank when the fuel low level came on and how close to E I REALLY WAS when the needle hit the bottom of "E". Any experience out there with this? Just how tolerant are these fuel delivery systems to Burping? ie sucking air. Old school diesels fuel systems I have heard through the grapevine need bleeding but I have no Idea how these modern high pressure injection engines tolerate air ingestion. I have read that the fuel system needs purging when changing fuel filters by running two pumps via plug in software or manually jumping the pumps ..... Sounds like a pain in the ass. Yet others say just top off the canister really well and no problems ..... Just start er up. Thoughts? I'm thinking of doing my own fuel filter changes but don't want to fry the hp pump. All for saving a few bucks on a filter change.

Have you considered the possibility that your fuel gauge/sender unit is inaccurate? Why not just drive it and track your mileage and not worry whether the gauge tells you the tank is full or not?

SoTxBill · Apr 14, 2016

South Coast Guy said:
Have you considered the possibility that your fuel gauge/sender unit is inaccurate? Why not just drive it and track your mileage and not worry whether the gauge tells you the tank is full or not?

Full, not so much important... EMPTY is very very important.

hhead · Apr 14, 2016

I use to worry about it, before I realized I was getting minimum 600 miles to a tank! Now not so much

Rico567 · Apr 14, 2016

Flyboy777 said:
<snip>Thoughts? I'm thinking of doing my own fuel filter changes but don't want to fry the hp pump. All for saving a few bucks on a filter change.

As "The Grove" suggests, I generally fill up at or just before the fuel needle gets to the red lines on the left hand side. No sense in pushing it.
I changed my fuel filter week before last. I used VCDS to prime it after replacing, but I also filled it to the brim with Power Service after I lowered the new filter in, so priming probably wasn't necessary. Lots of people seem to do it that way (not priming, just filling up the canister) and it starts right up and runs fine. Piece of cake, really. Five T-20 torx screws out (don't lose the washers), pull off the top (good idea to surround the canister with paper towels in case of any slop), lift out the old filter, lower in the new, top up canister with PS or clean fuel, replace the screws and fire it up.

jrm · Apr 16, 2016

my 2013 runs the tank pump when the key is turned on, verified this by turning the key on during the filter replacement. can was half full with just one key cycle.

Brad95 · Apr 23, 2016

jrm said:
my 2013 runs the tank pump when the key is turned on, verified this by turning the key on during the filter replacement. can was half full with just one key cycle.

mine does the same!

tdiatlast · Apr 24, 2016

^^^some NMS Passats do this, some don't. Don't know which VIN vehicles have this feature.

jrm · Apr 24, 2016

may have been same rolling model year updates as the gas hood strut, 0020 turbo and fog lights that light up as the wheel turns. Springish 2013 but one can here the pump loud and clear matches the glow plug light duration

psd1 · Apr 24, 2016

My 2013, built Dec 12 runs the pump. When I change fuel filter I simply pop in a new filter, cycle the key several times and fire her up.

I have been able to put 18.6 gallons in my passat. Needle reads full. Average 750+ miles per tank.

Booth44 · Apr 25, 2016

I've only taken my TDI down to the point where the display shows my range to be zero one time. I did a slow fill to the very top and I was able to get 66.744 litres in, which converts to 17.63 gallons.

If you are new to diesel - as I am - diesel foaming is one of the things that takes awhile to adjust to, if you like to fill your tank yo the very top. You really have to take it slow and wait the extra 20-30 seconds.

tdiatlast · Apr 25, 2016

Given the known fragility of the fuel system, I think driving deeply into the "red" zone is high-risk. For me, it's just not worth the risk.

jrm · Apr 25, 2016

tdiatlast said:
Given the known fragility of the fuel system, I think driving deeply into the "red" zone is high-risk. For me, it's just not worth the risk.

Exactly, not until a Engine oil lubricated HPFP is developed

Rico567 · Apr 25, 2016

tdiatlast said:
^^^some NMS Passats do this, some don't. Don't know which VIN vehicles have this feature.

Our '13 Passat SEL Premium (May build, evidently) will NOT turn on the lift pump by turning the "ignition" on with KESSY. This pump -with the car quiet- makes a very distinctive high-pitched whine coming from the back. I cycled mine with VCDS.
OTOH, enough people have changed out the fuel filter in these CKRA cars by just pulling the old filter, lowering the new one in, and topping up the canister with diesel or something like PS white bottle. I've never heard a problem reported after doing it that way.

compu_85 · Apr 25, 2016

Remember that the vent button on the NMS works opposite compared to the older cars: the button is in the filler neck and the nozzle pushes it in. When the button is pushed the vent is closed. Solution: Pull the nozzle out. This will vent the tank. If you get a nozzle that can trickle fuel you can hold the nozzle out and add until the level is at the top.

Generally I get at least an extra gallon in when doing this.

-J

Kincora · Apr 30, 2016

I've noticed on my 2012 that if parked on a slight incline with front wheels on higher ground when filling up, it takes 60-80 miles before the needle reaches the first 1/16 gauge mark. Flat surfaces means it's going to be moving the the first gauge mark by 40 miles.

jck66 · May 2, 2016

compu_85 said:
Remember that the vent button on the NMS works opposite compared to the older cars: the button is in the filler neck and the nozzle pushes it in. When the button is pushed the vent is closed. Solution: Pull the nozzle out. This will vent the tank. If you get a nozzle that can trickle fuel you can hold the nozzle out and add until the level is at the top.

Generally I get at least an extra gallon in when doing this.

-J

What he said. After the pump first clicks off, pull the nozzle out and trickle fuel in and you should be able to do 1/2 gallon relatively quickly, then the second 1/2 gallon slowly, then watch out because you don't get much warning when it becomes overfilled and spills on your paint.

FWIW, my biggest fill to date was 18.5 gallons - I was really pushing my luck on that one. I usually run the MTG display (nearly) to zero, then fill and get around 17.5 gallons in.

MichaelB · May 2, 2016

jck66 said:
What he said. After the pump first clicks off, pull the nozzle out and trickle fuel in and you should be able to do 1/2 gallon relatively quickly, then the second 1/2 gallon slowly, then watch out because you don't get much warning when it becomes overfilled and spills on your paint.

I did that once and the same thing happened. It filled to the top and the excess fuel ran out into the filler door pocket down the side of the car onto the concrete and then I was standing in it. Nice huh? Now I just fill till it clicks off give it one more click and call it a day. All for 1/2 gallon of fuel not worth the hassle .......forget about it.

Flyboy777 · Jun 29, 2016

Ok just a quick update. I did a really slow fill and it took the needle up to pegged at full with an initial range close to 1500kms! Amazing , I love this car! It appears to me that Diesal foams easily and because it is thick it takes a long time to de foam. SO NOW WITH A SLOW FILL I'm getting in approaching about 62 litres. As far as I can tell the 0 range mark equates to 8 litres ( 2usg) remaining as reserve. That is what the owners manual states 70 litres including an 8 litre reserve. No need to stress at 0 range as that is about 150km at least theoretically. Obviously the tank will burp before then.

Flyboy777 · Jun 29, 2016

Kincora said:
I've noticed on my 2012 that if parked on a slight incline with front wheels on higher ground when filling up, it takes 60-80 miles before the needle reaches the first 1/16 gauge mark. Flat surfaces means it's going to be moving the the first gauge mark by 40 miles.

Thanks it is all about your attitude ..... As in the cars attitude. I have a snowmobile that takes a LOT more fuel when the nose is up. So I'll give that a try ..... Thanks.

Jetta_Pilot · Jun 30, 2016

Kincora said:
I've noticed on my 2012 that if parked on a slight incline with front wheels on higher ground when filling up, it takes 60-80 miles before the needle reaches the first 1/16 gauge mark. Flat surfaces means it's going to be moving the the first gauge mark by 40 miles.

I've driven Diesel cars all over Canada, a large part of the USA and a good part of Mexico since the mid 1980's and have yet to find a filling station where the pumps area is NOT level. That includes Tennessee !

czeetah · Jul 14, 2016

Jetta_Pilot said:
I've driven Diesel cars all over Canada, a large part of the USA and a good part of Mexico since the mid 1980's and have yet to find a filling station where the pumps area is NOT level. That includes Tennessee !

You have to get a station where the pumps are on a little island. You pull your wheels up onto the island. Imagine if you will parallel parking and getting way too close to curb and ending up with wheels on sidewalk/curb. Same principle.

The other thing you can do is whip the hydraulic jack out and lift up the back of car on tank side.

dbias · Jul 18, 2016

Jetta_Pilot said:
I've driven Diesel cars all over Canada, a large part of the USA and a good part of Mexico since the mid 1980's and have yet to find a filling station where the pumps area is NOT level. That includes Tennessee !

In West Virginia I have yet to find a station that IS level. And I do find that pointing the front of the car uphill does help getting more fuel in. I'm thinking the pipe must connect towards the front of the tank.

Fill up volume of 2012 Passat TDI

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