How best to clean your diesel fuel system?

Submitted: Friday, Jun 18, 2004 at 06:36
ThreadID: 13882 Views:16306 Replies:8 FollowUps:7
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Gday All,
I am going to replace my diesel injectors shortly (1997 2.8 GQ TD 113K km) but i want some ideas on the best way to fully flush/clean the entire fuel system. I have recently replaced the fuel filter and noticed quite a bit of red bulldust - fine stuff stuck in the old filter - so i want to clean out the entire fuel system from tank to injection pump to prepare for the new injectors shortly.
Heres my thoughts on it - please feel free to correct me or suggest otherwise:
1. Drop fuel tank - inspect and flush clean.
2. Replace fuel filter
3. Inspect fine gauze / mesh screen in the injectore pump banjo and clean as per manual says - replace banjo with new washers ($2 from Nissan!)
4. Now i can replace my injectors with clean ones from United Fuel Injection

The reason why i want to do an entire system clean is that there is a lot of red bulldust clinging to the INSIDE of the fuel filler. And i am assuming that there is more down the bottom of the tank hence the stuff caught in the previous filter.
Some hints on how best to rinse a fuel tank would be great too.

Cheers All
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Reply By: Truckster (Vic) - Friday, Jun 18, 2004 at 11:23

Friday, Jun 18, 2004 at 11:23
Remove fuel tank and flush with Petrol.. Leave to dry (even 500ml of petrol in 95ltr diesel tank wont hurt)

While tank is off, remove hoses from filter, or leave on to see how much comes out... Blow out lines with Compressed Air

Take out and check IF your car has the Gauze filter then leave it on the bench.. Dont replace the gauze filter. Many GQ has stopped cause they are blocked.

Then try new injectors. While your at it, why not get fuel pump sorted out too get all the crap sorted out in 1 go..?
Hi Flo are good for injectors too

Good luck
AnswerID: 63735

Follow Up By: Quartzy - Saturday, Jun 19, 2004 at 00:59

Saturday, Jun 19, 2004 at 00:59
Cheers Truckster!
What treatment would you recommend for the fuel pump?
How would i go about it?
Also, I'll check out Hi Flo.
FollowupID: 324998

Follow Up By: Truckster (Vic) - Saturday, Jun 19, 2004 at 01:59

Saturday, Jun 19, 2004 at 01:59
getting it re-conditioned, or serviced... it isnt cheap, but it will give you the most out of your donk
FollowupID: 325000

Reply By: Patrol22 (Queanbeyan - Friday, Jun 18, 2004 at 11:24

Friday, Jun 18, 2004 at 11:24
Hey Quartzy - can I ask why you are changing your injectors if you have only done 113000kms? My 1998 GU 2.8tdi has 140000kms on it and have been advised to leave the injectors alone unless they start playing up. Also can't understand why you would get dust in any quantity in the fuel system - perhaps you can enlighten us on that as well.
AnswerID: 63737

Reply By: Peter Guy - Friday, Jun 18, 2004 at 12:18

Friday, Jun 18, 2004 at 12:18
Yes me too, I'm curious as my GU 2.8 Patrol has 198,000 kls and have never touched the injectors. Also you must have a split in your tank to allow the dust to get in.
Have you noticed whether it biuilds up pressure on a hot day when you undo the tank filler cap.
Cheers Peter Guy
AnswerID: 63750

Reply By: Rob W. - Friday, Jun 18, 2004 at 13:33

Friday, Jun 18, 2004 at 13:33
It may not be bulldust. It might be some type of "algae" that can live in diesel. I remember something about the discovery's having a problem with some sort of algae/bacterial growth in the fuel tank, but am unsure of the details. Maybe someone with greater knowledge can comment.


AnswerID: 63760

Follow Up By: Les Webb - Friday, Jun 18, 2004 at 21:14

Friday, Jun 18, 2004 at 21:14
Algie will grow in tanks where water is present. All tanks collect some condensation. Some fuels can be highly contaminated. Maybe "FuelDoctor" shock treatment would be advisable...maybe several doses..
FollowupID: 324972

Reply By: Quartzy - Saturday, Jun 19, 2004 at 00:57

Saturday, Jun 19, 2004 at 00:57
Cheers Guys for helping me with your responses.
To answer a few questions: the reason i am wanting to replace injectors is that at idle they appear to be injecting too much diesel into the engine - very smelly and unburnt diesel smoke appears after leaving car for any period at idle. Also, on startup they 'splut' for about 6 - 10 seconds until operating normally. I dont know if this is related with injectors but my fuel consumption is around 14.5 per 100km or even just above 15 l per 100km - dont forget i'm in the country with no traffic lights and big open runs @ 100km/ph unloaded. It seems too much. Around town @ 60 kph i can get 13 l per 100km for a tank.
The red dust is exactly that - i got some residue out of the old filter and dried it out - it was good old North west red fine dust! My car has had its entire existence up here in North of WA so I'm sure some of the dust has worked its way in to the system - perhaps through the breather near the fuel spout.
I think once i have cleaned the system i will use an additive/cleaner.
AnswerID: 63850

Reply By: Peter O - Saturday, Jun 19, 2004 at 01:51

Saturday, Jun 19, 2004 at 01:51
Hi Guys,
check out this site, should be handy in preventing any alge in the future.

Fits between the fuel tank and the filter to break up any alge that is almost always found in deisel tanks. This unit consists of some strong magnets that break up the alge as they pass through the magnetic field small enough that they pass through the fuel filter and are burnt in the cylinders.

A mate of mine has one fitted to his 40 Foot boat and has never found any sign of alge on the filters.

AnswerID: 63851

Reply By: B3 - Saturday, Jun 19, 2004 at 05:56

Saturday, Jun 19, 2004 at 05:56
You are doing the right thing replacing your injectors. Generally it is recommended that they are serviced every 70000km and Hiflo state that under no circumstances should pintel type injectors go more than 100k without service.
Remember that it the spring loading in the injector helps control the timing of the burst of fuel that is released into your cylinder. If the spring is weakened/worn the motor will still run but it is possible that the fuel is overcoming the spring too early and hence too much fuel being injected prematurely. In extreme situations this can cause serious damage to diesel warned!
AnswerID: 63854

Follow Up By: Jonoc - Monday, Jun 21, 2004 at 22:39

Monday, Jun 21, 2004 at 22:39
I study microbiology at uni, and i have no doubt all sorts of funky bacteria (maybe a few types of algae not my area of interest to comment havn't found any journal articles on algae and diesel) reside in the fuel tanks of not only Diesel 4x4's but also in petrol ones.
Going out on a limb fuel filters would probably not filter them out (unless you havn't changed them for a long time) as we are talking some seriously small organsisms maybe 20 micrometers (1000th of a mm). Therefore these would end up being fried in the cyllinders and ending up as carbon deposits in the engine.

Therefore in my opinion forking out for any of those biocides is pretty much a waste of time especially since we are talking some of the most adaptive bacteria which would probably end up using the "biocide" as a food source anyway after a while. (happened with some petrochemical based disinfectants in hospitals).
FollowupID: 325409

Follow Up By: Peter O - Tuesday, Jun 22, 2004 at 11:44

Tuesday, Jun 22, 2004 at 11:44
Hi Jonoc,
Just going by what I read in an article in the 4x4 Aust magazine in Dec02 and the follow up in April03. both of these are available on the De-Bug website. The concern with these types of algae is that they multiply quickly in the right conditions(doubling in number every 20 min according to the april03 article) and form long strings of slime causing problems such as restricted fuel flow and blocked filters. These micro-organisms are refferred to as Hydrocarbon Utilising Micro-Organisms which are more than 250 in number.
This the link

Having said all that I spoke to Ron Moon personally about the articles and he only decided to them after he had tested the unit on his own vehicle.

FollowupID: 325455

Reply By: Jonoc - Tuesday, Jun 22, 2004 at 21:30

Tuesday, Jun 22, 2004 at 21:30
Okay , I haven't found much in the journals , so i have sent an e-mail to the guy in charge of environmental microbiology at uni.

However, I am a bit sceptical about that artical.
Any microbe (that will grow) can grow rapidly "under the right" conditions, but the conditions in a diesel fuel tank will never be a really nice place to grow and i doubt anything would come close to having a doubling time of 20mins in a diesel fuel tank which would be a very very harsh environment. Hell, E. coli struggles to have a doubling time of 40 minutes at 20C in a specialised growing medium.

secondly, i do not think algae would grow at all in a fuel tank (i could be wrong)
Those picture's could just be rust, unless the gunk from the fuel filter grows in culture or you look at the stuff under a microscope it is fairly difficult to say it is anything.

Hate to be a sceptic, but thats my two bobs worth. I could be wrong though as anything can happen in the wacky world of bacteria.

AnswerID: 64510

Follow Up By: Jonoc - Thursday, Jun 24, 2004 at 01:19

Thursday, Jun 24, 2004 at 01:19
Ok , the word from the environmental microbiologist is.

Most fuel contamination problems are caused by Cladosporium resinae a type of fungi (like beer makers yeast or common bread yeast). Most (almost all) diesel is contaminated with microbes , but they pose almost no problem unless fuel is saturated with water and nutrience(causes its own problems).

Algae is not a problem unless your in the habit of exposing your fuel tank to sunlight for extended periods of time.

Microbial contamination of fuel tanks is only a problem in fuel that has a very high water content. If the water content is high enough doubling time can be around 20mins for some bacteria depending on many factors

From what i understand the problem is most often associated with crappy watery fuel which may cause more problems in itself.

Microbial contamination can be limited by using good fuel.

Interesting note is that most of the engine problems associated with microbes in the fuel are their bye products cause increased corrosion and blistering of some of the fittings in the fuel system. Secondary problems are with blockages.

more information

If you have anymore information please send it to me as this area fascinates me.

cheers Jono C
FollowupID: 325795

Follow Up By: Peter O - Thursday, Jun 24, 2004 at 10:13

Thursday, Jun 24, 2004 at 10:13
Hi Jonoc,
I agree with your views regarding water in diesel, that is what the article mentioned. It also states that the only place that the algae grows is in the fuel water interface which according to the microbiologist you spoke to is spot on.

My point regarding the De-Bug unit is that it costs around $400 to fit depending on the size of the unit recommended for the vehicle. considering the amount of money we spend setting up our rigs it is cheap insurance for us because we never know what type of diesel we are buying at any service station around the country.

cheers Peter
FollowupID: 325821

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