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lesapandre

Something Nasty in my Tank

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Bit of a tech one this. My Citroen AX diesel which I have not driven for a year was off for its MoT. Nice. 

I just had got onto a busy road when it coughed and started to die so I coasted onto a side road and parked up. Not so nice. No tools - only some old scissors in the car.

Fuel was a bit low so I got 4 litres of soya oil across the road and expected to be on my way (I run it mostly on diesel) if it had run out. I was sure it hadn't 

Nope.

Keep cranking  and sputtering. A quick look under the bonnet nothing untoward except the hand primer bulb was deflated - a bit like me. No MoT today. Drat.

First thoughts were a perished bulb (its rubber) but prising the clips off with the old scissors and testing it- the valve worked fine and it was not worn.  No fuel though and sucking the pipe from the tank produced no welcome mouthful of derv.

So what next I'm sort of stranded. Think.

Next job was to pull the back seat up and look at the tank pick-up - it's an easy job with an AX - one big screw-fixing (again the scissors came in handy to budge it)  and the fuel float etc come out with the fuel pick-up. Not done this before.

Wow - under the gauze on the pick up and in the pipe out of the tank there was a sticky brown gunge - a bit like clay - a wonder the car had run at all. When I got it off and blew down the pipe completely blocked.

I got the pickup home on the bus and having got the gauze off and rodded out the pipe with an old coat hanger and then flushed it with cooking oil - it came clean after a lot of work. This stuff is super-sticky

This was a build up over years furring up the intake  - and leaving the car allowed it to dry in the pipe I think.  It's the kind of thing it didn't occur to me to service. I think there was just enough diesel in the fuel line to start the journey.

All back together and priming the diesel pump the car started first time. No problem with air in the system either. I had to Araldite the mest gauze back on the fuel pick-up - I dont think it was supposed to come off. The internal uptake pipe is about 4mm underneath it. This is it upside down - the tape is to stop it falling over while the glue dries. The brown stain is more of the gunge stain on the outside of the pick-up. The 'tin' has the fuel gauge float in it. It drops the other way up into the fuel tank.

20191108_155749.thumb.jpg.f64cfee2a10d07b23e621464bb65d1b1.jpg

Just an interesting one if your diesel does run badly - it may be something as straightforward as this - something nasty lurking in the fuel tank over years.

Now to get that MoT.

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Welcome to the joys of diesel bug.  It likes to grow in old two stroke oil turning it acidic and dissolving Trabant carbs from the inside out too.

There's a biocide solution you can get to help kill off any existing colony in the tank and lines, you'll definitely want to do this or it will likely grow back again quite quickly.

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I’ve found that fuel bug treatment to be pain in the ass. It might kill the bug but the slimy shite still lingers and keeps blocking filters/ pumps . 
Where I used to work I saw loads of combines and rarely used tractors with the problem . 
Proper solution was to remove the tanks and steam them out with a jet wash as hot as it would go then dry with a hot air gun shoved in the filler neck .

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Very sticky indeed and probably toxic - took ages to get off my hands as when I broke down as I had no gloves. I'm going to fill the tank with diesel and use the car next week to blow it out a bit. 

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Worth sticking an injector cleaner in it? B and mp's sell that stp stuff....I bought about 20 bottles of it because I think they sell it for £2.99 a bottle or something like that....

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one trick i have heard done with the tank off the vehicle is to give it a good swill with petrol/parrafin/mixed solvents, leave for a bit, swill again then set the bloody thing on fire, let it burn a bit until the crap is gone then smother the filler intake with a old saucepan.... bearing in mind the only source of oxy is the inlet and outlets.... it does clean the tank out.....

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Yeah...even if you kill it, the remains will still be there...so I'd consider that a *part* of the solution.  Thoroughly cleaning the tank is an essential part of it though.  I'd probably look to get the tank thoroughly cleaned, replace as many of the fuel lines as are readily accessible as possible and the fuel filter...then add the biocide to nuke anything that's left to help prevent it from returning.

Thankfully not something I've (yet) had to deal with personally yet.  Given I have a diesel on fleet now though I'm sure my turn will come.  Bloody 70 litre tank too so it will be a royal pain to drop and refit I'm sure...

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Looking into this a bit more it is apparently quite common (and nothing to be embarrassed about).

It's a bacteria that is propagated by water droplets in the tank (a doctor once treated me for that too). The easiest way to avoid it is to keep the tank topped up to avoid condensation. Regular use helps.

Particularly common in marine diesels for obvious reasons and particularly when the boat is used sporadically. 

There are various brands of additive available - so I will get something to put in - the marine version may prove cheapest as it's all the same stuff and the AX engine is pretty basic. Will treat 1000's of litres.

What a saga - at least I avoided a parking ticket - car started first time again this afternoon and I topped the tank with fresh diesel to be on the safe side.

Now all I need is a fresh MoT.

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As you say, 'diesel bug' is more of an issue (usually!) with boat engines and is always featuring in boating/marine magazines. I think it's worse in winter presumably when it's not being used. 

 

A friend used to basically drain his tank before laying up for the winter and dose the rest with a strong amount of additive, then when re-comm-ing the boat in the spring, would put several gallons of fresh diesel in, fire the engine, run it for 15 mins then change the fuel filter. He never had any issues with fuel blockage despite sometimes fuelling from some sketchy sources!! And yes, I think the marine additive is cheaper as they use it alot more. 

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Interesting, I've heard of diesel bug but this is the first time I've seen it for real.

If running a car in veg oil cleans the tank what would happen if you put some in this? Would it help or hinder, assuming you had enough inline fuel filters to cope with the crap it'd drag through?

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bad as using bad batch of bio diesel, and having to clean what looks like a bad sneeze from King Kong out of the tank and lines!!!!!

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1 hour ago, dome said:

Interesting, I've heard of diesel bug but this is the first time I've seen it for real.

If running a car in veg oil cleans the tank what would happen if you put some in this? Would it help or hinder, assuming you had enough inline fuel filters to cope with the crap it'd drag through?

It will screw the seals in your pump...ask me how I know.....(recent volvo 850 roffle)....

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