fungus and dirty fuel in fuel tanks.

Submitted: Sunday, Apr 24, 2022 at 13:26
ThreadID: 143609 Views:6445 Replies:13 FollowUps:6
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Good morning to all you happy travellers.
I have never had the problem of dirty fuel and fungis in my fuel tanks, so I am looking for people that have had this experience, that would like to share their knowledge, first , how did they discover they had dirty fuel, and second what measures they took to prevent it happening agian.
We are intending traveling from fortress W.A to the great Victorian state, and New South Wales, and it seems that the fuel can be contaminated in the rural areas of those states, in saying that I believe it can happen all over Australia. So any advice would be greatly appreciated.
We drive a 200 series landcruiser towing a 23 ft van, so your help is appreciated.
thank you
Broodie H3
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Reply By: Peter_n_Margaret - Sunday, Apr 24, 2022 at 13:34

Sunday, Apr 24, 2022 at 13:34
Fungus can grow on the diesel/water interface. It is a white gel like substance that will block fuel filters and make a mess of fuel systems. I have had it grow in the bowl of a CAV filter.
It is rarely a problem for vehicles in constant use, but having a good water seperator in the system is a good idea. There will almost always be some water in fuel.
Carry spare fuel filters, and don't worry.
If the vehicle is parked up for any extended periods, I always add a biocide to the fuel to stop the fungus from growing.
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Reply By: Ozi M - Sunday, Apr 24, 2022 at 15:18

Sunday, Apr 24, 2022 at 15:18
No one I know has had a problem with bad fuel for a long time, we tend to fill the tank full when we fill so no room for anything else.

We also use premium when available, either BP or Ampol( old Caltex Vortex) and fill up, they both have detergents in them which we assume will clean any small bits of rubbish from the tank as it sloshes around.

Most service stations on main roads have much better storage than in the old days, less leakage and rubbish in the fuel.

The only recent bad experience I can recall was when they put the wrong fuel into the storage tank at Alice Springs BP (?) a few years ago.

That was a stuff up that was fixed AFAIK
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Reply By: Member - McLaren3030 - Sunday, Apr 24, 2022 at 17:56

Sunday, Apr 24, 2022 at 17:56
As a general comment, the fuel whether Petrol or Diesel supplied by the major Oil Companies will meet or better the current quality specifications. The main issue with contamination generally occurs either at the Service Station/Fuel Outlet, or in the Tank Truck delivering the Fuel.

The most common contamination problem is from water ingress into the service station tanks. The next common issue is from a product “crossover” where a tanker driver mistakenly drops petrol into the diesel tank, or diesel into the petrol tank. Next would be when a tanker driver does not drain a compartment that previously contained a different product before filling with another product. As far as fungus bacteria is concerned, as someone else has mentioned, this can grow on the water/fuel interface.

Of course, there is always the issue when a driver contaminates his own fuel tank by filling with the wrong product. This is obviously not a quality control issue with the service station or the fuel itself, rather a mistake on the drivers part.

Contaminated fuel at a service station is costly to either the Service Station owner/franchisee, or the Oil Company, not only in recovery costs, but even worse if it gets into a customer’s fuel tank. The cost of recovering the contaminated product is expensive. If the contamination is caused by a leaking tank, the cost is born by the franchisee/owner. If it is Tanker Driver error such as a crossover, then the Transport Company may have to wear the cost unless it can be shown that the filling points are poorly signed.

When fuel is recovered from a contamination, the original cost of the fuel still has to be paid. In some cases, a rebate may be offered, but it is at a much lower price than the original cost of the fuel. It is generally considered to be “slop”.

What happens to this contaminated fuel? In areas where there is still an operating refinery, it can be transported back to the refinery for reprocessing at the refinery’s discretion. Where there isn’t a refinery, it can be “blended “ off in small quantities with good product. This takes quite a long time and is generally not an option. The third option is to load it onto a ship and send it back to a refinery overseas for reprocessing, again at the refinery’s discretion, a very costly exercise.


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Reply By: lindsay - Sunday, Apr 24, 2022 at 21:53

Sunday, Apr 24, 2022 at 21:53
One of the issues is the tank being in a half filled tank where the fuel expands during the day and at night as it contracts it will suck air into the tank. If there is moisture in the air that will end up in the tank. Over time that will increase the amount of moisture in the tank. So if not using you car for a while keep the tank full to minimise the problem.
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Follow Up By: Member - McLaren3030 - Monday, Apr 25, 2022 at 08:55

Monday, Apr 25, 2022 at 08:55
Hi Lindsay,

It really does not matter whether than tank is full or empty, thermal expansion will still occur. If the tank is full, thermal expansion is likely to push fuel out of the filler cap, the resultant “space” created will then allow moist air back into the tank as things cool down.


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Reply By: Dean K3 - Sunday, Apr 24, 2022 at 22:51

Sunday, Apr 24, 2022 at 22:51
Diesel will certainly grow algae if left stored and unused water contamination is also a possibility esp if tis from 44 gallon drums out bush (rarity these days though)

if you worried get some F10 fuel treatment from industrial chemical technologies (ICT) most automotive supply shops stock it (Repco autobahn etc) use 100ml per fill up 1 litre bottle costs about $40 to 50 mark. 1 litre will treat 4000l so lasts some time at 100ml each fill up or alternative fill up.

I know it certainly lowers emission ran a single treatment through folks 80 series (diesel engine) runs tad rich one treatment on fill smoke disappeared then it reappeared again with no treatment on the next fill up

website has a few videos to look at as well

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Reply By: Athol W1 - Monday, Apr 25, 2022 at 07:52

Monday, Apr 25, 2022 at 07:52

The best thing that you can do if you are concerned about getting 'dirty' fuel is to carry spare fuel filters and know how to change them, and also how to reset the fuel filter light on the dash. These 2 proceedures are quite simple to any one with any knowledge on the use of tools (any tradesman or handyman).

I have travelled outback Australia quite extensively over many years, and refuelled from very remote fuel outlets, and have yet to suffer from Alge or water in the fuel. It is my opinion that those who fuel from drums at fuel dumps, or from Jerry cans being carried, have the greatest risk of getting dirt, or water, in their fuel.

Should you decide to fit a 'pre filter' to your 200series then in the case of the CAV filters they will collect most of the water that may be present, but will have to have regular inspections and draining as required. They will also act to remove the rocks from the fuel but it is still the Toyota filter that is most likely to be the one that gets blocked.

Enjy your trip, and do not get paranoid about getting 'dirty' fuel.
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Reply By: Banjo (WA) - Monday, Apr 25, 2022 at 09:42

Monday, Apr 25, 2022 at 09:42
How prevalent is the fungus thing?

In 25 years of owning a diesel I've never had, seen or had friends with fungus/gel, or whatever.

I'm not saying it isn't an issue but other than seeing it mentioned on the internet, but have no experience of it at all.
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Reply By: tonysmc - Monday, Apr 25, 2022 at 11:22

Monday, Apr 25, 2022 at 11:22
Hi Broodie, I put a Fuel Manager filter kit in my Hilux many years ago. I only went for this brand because the kit had all the brackets and gear to make it an easy fit and also had mounting for the battery isolator. I also purchased the water alarm (extra cost purchased separately) as I couldn’t see the point of having a water trap and not being informed if there’s water in the fuel immediately. From what I have heard most engine troubles from fuel issues happen not long after filling/topping up, so a visually checking a fuel bowl is fairly useless. I put mine as a pre-filter as I felt it was better and at the time the pre filter didn’t effect warranty, however post filters “may” have, and yes I had that in an email. While the OEM filter does have a water alarm, I always hoped that if I did get water I would get the pre-filter alarm and stop the car before activation of the OEM alarm and then I hopefully caught it in time. So are they necessary? Probably not however I put my on after a close friend got a bad batch of fuel and his car was out of action for a couple of months while dealing with cost recovery from fuel company.
While my alarm never went off due to water (yes it worked) I felt it was well worth the money for the peace of mind and the filter was being used every moment I was driving, unlike the 1000’s of MaxTrax’s being carried around that will never get used and cost more $. I would say if you are thinking about it now, put one on with both filter and water trap with a water alarm and enjoy the trip without that worry in the back of your mind. Tony
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Reply By: Member - Rowdy6032 (WA) - Monday, Apr 25, 2022 at 16:11

Monday, Apr 25, 2022 at 16:11
On another forum a recent report of dirty fuel being purchased from a servo in Lancelin. The vehicle towed to Jurien for repairs. Just have to be unlucky I guess, but it does happen.
AnswerID: 640330

Reply By: Rangiephil - Monday, Apr 25, 2022 at 16:44

Monday, Apr 25, 2022 at 16:44
If you are paranoid ( like me) you could buy a Mr Funnel, which lets diesel through but not water.

I have only used it once but even with the biggest one it is a slow process and would only be used if say decanting from a station above ground tank into a jerry can. The lady at the WA petrol station seemed a bit insulted that I used it. LOL
Last year I picked up some bad diesel from a high volume station in Albury, and it only manifested itself with a drop out for 1or 2 seconds while cruising, however my TD5 is much more tolerant than modern common rail diesels. I use diesel additive that is supposed to dissolve water, and my fuel filter (much bigger than Jap ones) has a water trap and light which did not come on.
So in 8years I have had a total of about 10 seconds lack of power and I have a steel 150L tank which would be more prone to water formation than 80L plastic ones.

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Follow Up By: Member - William B - Monday, Apr 25, 2022 at 16:59

Monday, Apr 25, 2022 at 16:59
Years ago in a previous life we used to add metho to car fuel tanks that had some water in them, the reasoning behind it was that the metho would mix with the water and would then be mixed into the petrol.
Is this the same principle with diesel treatments?
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Reply By: Bob Y. - Qld - Monday, Apr 25, 2022 at 17:15

Monday, Apr 25, 2022 at 17:15
Toyota, in their wisdom, no longer include fuel filter changes in their servicing regime, Broodie, so astute owners always carry at least one spare fuel filter with them.

I had a fuel filter light come on in my 79 series ute, when a group of us were travelling from Newman to Karijini & Mt Meharry. Didn’t change it immediately, and performance wasn’t affected.

The filter looked like this, when I removed it.

No water(warning light was flashing), but filter element covered in this black gunk. Someone suggested I had algae in my tank?


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Follow Up By: Athol W1 - Monday, Apr 25, 2022 at 20:02

Monday, Apr 25, 2022 at 20:02
That is normal for a fuel filter where you can see the element, and especially with the modern common rail diesels as the size of the particles that can pass through the filter is just soo much smaller than what used to be taken as good filtration.

Every filter that I have removed from my 200 series TLC (between 2011 and 2015) and my Isuzu Dmax (2015 to present) have had a similar appearence.

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Reply By: Steven G1 - Thursday, Apr 28, 2022 at 17:44

Thursday, Apr 28, 2022 at 17:44
Hi Broodie H3,

Although I have had no trouble with dirty fuel for the past year I have been using Fuel Doctor each time I fill my tank. Have also used in the diesel heater, it really cleaned up the view line a treat so I gather cleaned the rest of the lines as well.

Good luck on your travels

AnswerID: 640373

Follow Up By: Member - McLaren3030 - Thursday, Apr 28, 2022 at 22:15

Thursday, Apr 28, 2022 at 22:15
Hi Steven,

If the Fuel Doctor cleaned up the clear fuel lines in your heater as you say, what happened to the “gunk” that was coating the fuel lines? Surely it has to go somewhere, I assume the fuel filter. I would assume the same thing happens when you add it to your vehicle fuel tank as well. Did you have to do a filter change after adding a fuel doctor?


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Follow Up By: Steven G1 - Friday, Apr 29, 2022 at 10:01

Friday, Apr 29, 2022 at 10:01
Hi Macca,

thanks for the question.

Fuel Doctor breaks down the contaminants and moisture/water into microscopic particles which then passes into the engine and gets burnt in the normal process. Refer to the Fuel Doctor web site and You Tube. Have always regularly changed the filters as per normal services. I highly recommend adding a product like Fuel Doctor to any petrol/diesel engine/motor. It also maintains longevity of stored fuels.

Cheers Steve
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Reply By: vjai 0 - Friday, Jun 03, 2022 at 14:18

Friday, Jun 03, 2022 at 14:18
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