Dirty/black fuel

Hey guys...

Getting some QUICKLY clogged fuel filters in the 04 PD... might this be oil in the fuel??

I was thinking it might be bad diesel fuel, but I've used the same station for the truck, and i'm not having any issues...

I changed the fuel filter 3 weeks ago, and the car quit running again (losing prime, as the in-tank pump is NOT functioning any longer ) I'm thinking either a clogged fuel filter, or a clogged inlet/screen in the in-tank pump from the dirty fuel??

Thoughts on where to start, and what to fix??

Thanks guys.

Sounds like it may be algae growth. Try a biocide and change your filter/clean your screens.

GR40RCapri said:

Hey guys...

Getting some QUICKLY clogged fuel filters in the 04 PD... might this be oil in the fuel??

I was thinking it might be bad diesel fuel, but I've used the same station for the truck, and i'm not having any issues...

I changed the fuel filter 3 weeks ago, and the car quit running again (losing prime, as the in-tank pump is NOT functioning any longer ) I'm thinking either a clogged fuel filter, or a clogged inlet/screen in the in-tank pump from the dirty fuel??

Thoughts on where to start, and what to fix??

Thanks guys.

Click to expand...

Your in tank fuel pump is broken? If so, fix it first.

Bill

tditom said:

Sounds like it may be algae growth. Try a biocide and change your filter/clean your screens.

Click to expand...

I had thought this a yr ago... I completely emptied the fuel system, new filter cleaned the in tank pump housing, wiped the tank, and flushed the system...

still there... that's why I was thinking oil in the fuel.... it's COKE colored..

40x40- yes, it's NOT working....

yet I didn't notice this until recently... didn't even know there was a pump in there until WELL after we bought the car...(hence, it wasn't working then...) have been told by a few that it's not a required piece to get the car to run, as the tandem will pull the fuel fine. which it has for 40k miles..

does it need to be fixed? yes, planning on that. For now, the 'cleaning the fuel' is the biggest concern. IF it's something with oil-into-the-fuel, I want THAT fixed prior to running it through a new pump... rather than replacing the pump and driving it with the same issue for a longer than it has been....

clear-as-mud?

Do you have a Pela or a MityVac? Suck some fuel out of your tank and look at it. Better yet, go to the station where you got the bad fuel and take a gallon sample. If it is "COKE colored" as you say. Show it to them and ask what's up. If they're pumping contaminated fuel they need to fix your problem.

Its not clear to me how oil would get into the fuel system in any large quantity.

So, let me get this straight. Car runs poorly or even stops running, so you pull the fuel filter and since it's black, you change it. You then get the car started and drive for awhile and it dies again.

Black fuel is normal in these PD engined cars, so the black filter isn't a good indication of if it's plugged.

If there was algae growth in the fuel system, you need to KILL it, not just clean the tank. If you don't kill it all, it will come back.

Fix the pump. Don't worry that the "contaminates" in the fuel are going to destroy your new pump, just replace it.

Could a leaking unit injector cause fuel to be contaminated?

whitedog said:

So, let me get this straight. Car runs poorly or even stops running, so you pull the fuel filter and since it's black, you change it. You then get the car started and drive for awhile and it dies again.

Black fuel is normal in these PD engined cars, so the black filter isn't a good indication of if it's plugged.

If there was algae growth in the fuel system, you need to KILL it, not just clean the tank. If you don't kill it all, it will come back.

Fix the pump. Don't worry that the "contaminates" in the fuel are going to destroy your new pump, just replace it.

Click to expand...

Black fuel is NOT normal in a PD TDI.

Black fuel comes from engine oil getting into the fuel. An easy place for this to happen is inside the tandem pump internally via the shaft seal between the two pumps. A leaking tandem pump seal may be caused by extra wear & tear from the pump having to suck fuel from the tank due to a dead in-tank lift pump instead of normally being helped by the lift pump. The vacuum created in the fuel side of the tandem pump may pull oil past the seal(s). The other side of the tandem pump is the vacuum pump (for brake booster and turbo control) and this pump is lubricated by engine oil and exhausts into the valve cover area.

I think it needs a new lift pump in the tank and a new tandem pump on the engine. Hopefully it's just oil getting into the fuel and not fuel getting into the oil.

Good luck.

40X40 said:

Your in tank fuel pump is broken? If so, fix it first.
Bill

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What 40X40 said.

n1das said:

... An easy place for this to happen is inside the tandem pump internally via the shaft seal between the two pumps. A leaking tandem pump seal may be caused by extra wear & tear from the pump having to suck fuel from the tank due to a dead in-tank lift pump instead of normally being helped by the lift pump. The vacuum created in the fuel side of the tandem pump may pull oil past the seal(s). The other side of the tandem pump is the vacuum pump (for brake booster and turbo control) and this pump is lubricated by engine oil and exhausts into the valve cover area...

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That makes sense- thanks.

However I would not conclude that the OP is seeing oil in his fuel because it could also be algae. I suppose a photo might help to determine which is most probable.

n1das said:

Black fuel is NOT normal in a PD TDI.

Black fuel comes from engine oil getting into the fuel. An easy place for this to happen is inside the tandem pump internally via the shaft seal between the two pumps. A leaking tandem pump seal may be caused by extra wear & tear from the pump having to suck fuel from the tank due to a dead in-tank lift pump...

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Good call David. What a great forum this is!

n1das said:

Black fuel is NOT normal in a PD TDI.

Black fuel comes from engine oil getting into the fuel. An easy place for this to happen is inside the tandem pump internally via the shaft seal between the two pumps. A leaking tandem pump seal may be caused by extra wear & tear from the pump having to suck fuel from the tank due to a dead in-tank lift pump instead of normally being helped by the lift pump. The vacuum created in the fuel side of the tandem pump may pull oil past the seal(s). The other side of the tandem pump is the vacuum pump (for brake booster and turbo control) and this pump is lubricated by engine oil and exhausts into the valve cover area.

I think it needs a new lift pump in the tank and a new tandem pump on the engine. Hopefully it's just oil getting into the fuel and not fuel getting into the oil.

Good luck.

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"Typical" would be a better word, I guess, but you are certainly right in the oil to fuel path.

n1das said:

Black fuel is NOT normal in a PD TDI.

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Apparently, combustion soot also gets into fuel via the injector and return line.
The filter normally can cope with this.
Please correct if wrong as I don't have a PD.

flee said:

Apparently, combustion soot also gets into fuel via the injector and return line...

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How?

flee said:

...The filter normally can cope with this...

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The fuel filter is not going to stop soot.

It goes past the combustion seal, past the lower seal and into the return.

I also seem to recall it being mentioned that it can go up inside the injector, but I don't quite believe this 100%.

You're telling me that an injector that has the ability to hold back thousands of psi can leak such that the soot post combustion can make it past two seals and back to the return? Possible maybe but not likely. That injector would be so bad that the car would barely run.

tditom said:

You're telling me that an injector that has the ability to hold back thousands of psi can leak such that the soot post combustion can make it past two seals and back to the return? Possible maybe but not likely. That injector would be so bad that the car would barely run.

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I think that is what DBW said.

EDIT: Now that I think about it more, I think that is goes external of the injector, not internal. The return passage is the lower passage, so if there was combustion gasses getting past the combustion seal and up the outside of the injector, it would get past the lower O-ring and into the return passage.

Here is a picture:

HERE is his post about oil.

Thanks, whitedog.

DBW said:

Some engine oil will mix with the fuel (very very small amounts). This small amount of oil will circulate back to the tank by virtue of the cooling function of the fuel return. The suspended soot in the fuel will adhere to the tank since there are no dispersents in the fuel to prevent adhesioin of those contaminants.

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Highlighted the pertinent parts. The tank might have a dark coating but it would not be suspended in the fuel in normal operation. I can see the tandem pump seals causing this- if it is in fact oil contamination (we don't know what it is at this point)

My PD never had black fuel.

whitedog said:

"Typical" would be a better word, I guess, but you are certainly right in the oil to fuel path.

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Yes, "Typical" would describe it better. My bad. My 05 PD JWagen has never had dirty/black fuel and just turned 150k miles.

To the OP, does it seem like oil consumption is higher than normal?

Could also be algae / critters growing in the fuel, as tditom said. If it's algae / critters growing, it needs to be KILLED with a biocide. Then it will probably need another FF change soon afterwards to get rid of the dead stuff that comes out after the biocide goes in.

n1das said:

Black fuel is NOT normal in a PD TDI.

Black fuel comes from engine oil getting into the fuel. An easy place for this to happen is inside the tandem pump internally via the shaft seal between the two pumps. A leaking tandem pump seal may be caused by extra wear & tear from the pump having to suck fuel from the tank due to a dead in-tank lift pump instead of normally being helped by the lift pump. The vacuum created in the fuel side of the tandem pump may pull oil past the seal(s). The other side of the tandem pump is the vacuum pump (for brake booster and turbo control) and this pump is lubricated by engine oil and exhausts into the valve cover area.

I think it needs a new lift pump in the tank and a new tandem pump on the engine. Hopefully it's just oil getting into the fuel and not fuel getting into the oil.

Good luck.

Click to expand...

Hmmm.... This is what I was thinking... So, unlike I have heard, NOT having a in-tank CAN eventually start to kill the tandem pump...? that's not cool. I have noticed some inconsistencies in the brake boosters performance.

Is this seal able to be changed out, or is it available??

The car still runs/drives great... WHEN it's running/driving

tditom said:

That makes sense- thanks.

However I would not conclude that the OP is seeing oil in his fuel because it could also be algae. I suppose a photo might help to determine which is most probable.

Click to expand...

I can do a photo....IF I can do a mobile upload easy enough... help! lol

flee said:

Apparently, combustion soot also gets into fuel via the injector and return line.
The filter normally can cope with this.
Please correct if wrong as I don't have a PD.

Click to expand...

I have heard this also...

n1das said:

Yes, "Typical" would describe it better. My bad. My 05 PD JWagen has never had dirty/black fuel and just turned 150k miles.

To the OP, does it seem like oil consumption is higher than normal?

Could also be algae / critters growing in the fuel, as tditom said. If it's algae / critters growing, it needs to be KILLED with a biocide. Then it will probably need another FF change soon afterwards to get rid of the dead stuff that comes out after the biocide goes in.

Click to expand...

It DOES seem like oil consumption is up. The pan does have a slight leak I need to get after, but it seems to be MORE than that, now that I think about it....

How can we tell if it's bio-contaminants and/or oil/soot contamination, or a combo??

Merry Christmas to all!!

Jay

How can we tell if it's bio-contaminants and/or oil/soot contamination, or a combo??

Merry Christmas to all!!

Jay[/QUOTE]

Oil analysis. Plenty of companies out there. I have used http://www.blackstone-labs.com/ and http://www.theoillab.com/ and maybe Polaris in Atlanta. There are plenty of labs out there.

GR40RCapri said:

...How can we tell if it's bio-contaminants and/or oil/soot contamination, or a combo??...

Click to expand...

Google "diesel fuel contamination" and compare some of those photos to what you see in your tank/filter.

roadhard1960 said:

How can we tell if it's bio-contaminants and/or oil/soot contamination, or a combo? Jay

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When the fuel in my boat tank was contaminated it had some almost gritty black gunk that would rapidly clog the filter(s).
If the black material seems really fine like lampblack them it probably is soot.
Adding some biocide is worth a try at no risk.

I am also amazed at the amount and depth of knowledge available on the TDI Club, and you guys are a good example!!

Oh and Merry Christmas to all!!! (and may your fuel not Jell!!)

*UPDATE*

BEW is Running again... Disassembled pump, etc, cleaned everything, tested pump per DanG144's post.. (Thanks Dan for the writeup )

I used a strap wrench to remove the screw-ring... worked WELL The screw-driver method liked to take pieces off the ring last time with only a little turn each time...

Pump was good to go... yet, no power when plugged in (tested before 100% reassembling...)

tested the harness plug, no power... powered the pump from the pump connector to 12v, power through the hanger to the pump, so the intank-unit was good

Tore the under-dash down to the relays to check... THEN low-and-behold, I found a missing fuse....

NOW we had power to the pump connector -ROCK!- reinstalled everything, primed the system, and removed the outlet hose from filter that leads to the fuel rail... well, shot some diesel over the valve cover...PLENTY of volume and pressure there! lol

So, I'd say that solves the loss-of-prime issue to the tandem... but, doesn't solve the oil-in-fuel issue...

Which brings us to THAT problem... I'm going to guess Tandem pump seal as *N1das*suggested.... It HAS to be oil contamination... it looks like VERY-thinned out motor oil....

I can post a picture if someone might be able to lead me to how?? to attempt a mobile picture upload...?


On to the next task... finding someone in the central MA area with a VAGCOM that might be able to assist us ... I have a MIL ... dealer said it's GP #3, "probably the harness..." the connectors are cracked after they changed the GP's to cover the recall....

I need an INSPECTION STICKER!! (can't get one with a MIL...)


THANKS GUYS!!!!

Missing fuse? How does that happen? Anyway, good detective work. Have you tried Auto Zone or some such to get a scanner on your car? They should be able to clear the code, but I don't know if it will stay off long enough to get your inspection.

Have you tried DeOXit on the GP connectors? That may be all that you need.

whitedog said:

Missing fuse? How does that happen? Anyway, good detective work. Have you tried Auto Zone or some such to get a scanner on your car? They should be able to clear the code, but I don't know if it will stay off long enough to get your inspection.

Have you tried DeOXit on the GP connectors? That may be all that you need.

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Hi White-Dog..

Not sure about the fuse? I've heard of others with it missing....

I have had the codes scanned there... I don't think they are 'allowed' to clear them, though...

And it prevents the system from being in 'ready-ness mode' which will FAIL you in MA when you go for a sticker....

De Oxit...never tried that..

J