Brown liquid in my diesel! What is it?

gaz_123

New Member
Was having issues with my T6, loud lumpy starts, ticking when cold, stalling etc. had it inspected and the fuel tank was full but in the diesel was a strange brown liquid, wasnt swarf, wasnt sludge just a brown liquid that when you shake it it doesnt mix just sits at the bottom whilst the diesel sits on top. Garage has never seen anything like it before and has ruled out diesel bug as it isnt thick. Anyone have an idea or seen anything like this before?

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Looks very similar to something I saw years ago - somebody put sugar in a fuel tank…..the guy had upset somebody and they were sneakily trying to get revenge 🥴
 
It’s the biofuel that has separated from the diesel.


It’s common if your van stands a lot. Using cheaper supermarket fuel. Refilling at less than empty.
We had company cars at work that only used supermarket fuel, refilled at 1/4 tank. Tanks full of bio gel, blocked the fuel lines starve the high pressure fuel pump and put metal into the injectors.

Resulting in new tank, sender, fuel pump lines, HPFP, and injectors. Irc the bill was around £4k each.

I would suggest removing the tank, back blowing the fuel lines from filter to tank and washing the tank out throughout.
Then only buy quality fuel like V power.
 
It's clearly more dense than the fuel, so water contamination seems likely.

Contrary to popular belief supermarket fuel is generally - but not exclusively- a safer bet in this regard. They're usually busy forecourts so tanks aren't left low or empty for long, giving less opportunity for contamination by condensation.

Or an older tank can allow the ingress of surface water through poor design or inadequate maintenance. Again, less likely to be an issue with the typically more modern supermarket forecourt.

Diesel itself carries inherently more H2O than petrol, hence the fuel filter acting as a water separator. Nevertheless, that looks more like contaminated fuel.

I presume any fittings at rhe top of the tank, lift pump, sender, etc, aremsecure and not allowing water in? Probably not but worth a look.
 
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UPDATE this brown stuff is now being tested as this was in march and all 4 injectors were shot and had to be replaced and a whole system flush with new fuel filter, all was and still is running perfect however 6 weeks later flashing coil light and p0087 low fuel pressure code came up. Since then i have had a new fuel rail sensor, no luck still the code cane back, and yesterday a new hpfp was fitted even though no signs of wear or swarf we bit the bullet as the code flagged up it intermittently lost 300-500 bar of pressure each time. So even after a new hpfp the van drives better then ever before however 165 miles in the code has flashed back up! Next steps is fuel rail and regulator and im hoping its one of them as everything then apart from the lift pump has been replaced. Anyone else had this or am i best to replace the lift pump first before the rail and regulator as this has already cost me £4.5k!!
 
Also still have the brown fuel from the above pics so we are just going to get it tested for the sake of it, another £20 for testing wont hurt when I've already spent £4.5k however testing after the flush and new injectors all came back clear so im hoping its all out the system now anyway but wont hurt knowing what it was in the first place!
 
Also still have the brown fuel from the above pics so we are just going to get it tested for the sake of it, another £20 for testing wont hurt when I've already spent £4.5k however testing after the flush and new injectors all came back clear so im hoping its all out the system now anyway but wont hurt knowing what it was in the first place!
This might be of use
 
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