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"Sugar in the petrol tank"

existentialist

existentialist

Tired and unemotional
Someone I know recently took a car into the garage - I'm not exactly sure of the nature of the problem, but the roadside recovery people had suggested there might be some kind of contamination in the fuel system.

And the garage confirmed this, telling them that there was sugar in the petrol tank, the fuel lines and that it had - in some not-terribly-specific way - done around £700 worth of "damage" by way of "contamination". They also said - quite definitively - that they thought it had been there over a year.

It's possible this is true, but I wanted to find out a bit more, so - with my friend's permission - rang the garage, to try and find out a bit more about this "contamination", and the line of reasoning that got them to their conclusions. I had to leave a voicemail, so I did - a nice friendly one indicating that my friend's distress at this news had prompted me to find out a bit more about it.

They haven't called back.

Now, there's a few things about this that make me suspicious.

First of all, sugar isn't soluble in petrol. If you put sugar in a petrol tank, it sinks to the bottom and stays there. Some of it could conceivably get pulled through the fuel lines, but it's going to get stuck when it reaches the fuel filter. It could even block the filter, causing the problems that first suggested something was wrong.

Secondly, "contamination" - a curiously apocalyptic word to describe the situation, especially when it is being coupled with a suggestion that a mere cleaning out of the fuel system is not enough.

Thirdly, unless the fuel filter is missing, or something equally improbable, sugar wouldn't enter the engine. If it did, it is still unlikely it would cause great harm, although I think we'd start to be looking at blocked injector feeds or carb jets (I'm not sure if it's a fuel injection job or not - it's a fairly elderly Peugeot 207).

I smelled a distinct smell of rat. My friend likes and trusts her garage, and is very uncomfortable about even the merest hint of a suggestion that they are either up to no good, or have got it wrong. I think they've either jumped to a string of wrong conclusions, or they're up to something. Since there cannot be very much in it for them to encourage a customer to write off their car, I'm inclined to assume the former.

Anyone here encountered the "sugar in the fuel tank" thing, and how did it pan out for you?
 
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I also smell rat, or at least fish, existentialist - however, sugar is soluble in water so if the fuel tank has water contamination (also at the bottom) then any sugar would dissolve and thus be dispersed and a small quantity of the solution drawn into the fuel lines (the mixture would separate on standing but driving any distance on roads, in their current rough state would definitely shake it about a bit ... and could the solution also "ferment" I wonder ?
Having had "water" contaminate a m/c tank a few years ago, this collected in the float chamber of the carb ...
E2A -
methinks a second opinion might be desirable, although given the age of the car that might be difficult to justify. Could you just happen to go with your friend to the garage when she asks for more detail / explanation ?
And do they sell cars ?
 
Anyway, some basics.

Carbs are long gone. Pretty much nothing from the 90s or later has them. They were replaced by port injection, and then more recently, direct injection.

Direct injection is susceptible to problems from carbon & gunk buildup, blocked injectors etc, because there's no washing effect from the fuel. However AFAICS there's only one 207 engine that uses this, the 1.6 turbo.

Sugar won't wreck your car but it'd still be expensive if you had to extract the fuel tank and replace the filter, which may be built into the tank.

Fuel contamination is a thing though, like this. On dismantling it, depending on what the contamination was, you might find gunk that you thought was sugar, maybe. And then you might have to replace lambdas, injectors etc, in which case it could add up to £700 easily enough.

If it were me, I'd not be too happy with that diagnosis, not so much because it suggests fraud but because it suggests cluelessness. I'd definitely get a second opinion, even if it meant having the car extracted and taken somewhere else.
 
Is it possible that your friend might be persuad to sell the car to the garage? They could then sort out the "problem" to sell the car on for a good profit. This has happened to my M-I-L. And with a garage that she'd used, and trusted, for many, many years
 
mauvais said:
What engine is it?
Click to expand...
It's an '04 petrol 207. I was keeping a very open mind, hence the carb mention, but you're right, it's not going to have a carburettor.

Anyway, I've had a long and friendly chat with the lady who runs the garage. Some of the story may have been lost in translation: the contamination is not definitively sugar, it's a black gunk that she describes as looking like "fossilised poo", large quantities of it in the tank. The car has had to have its fuel pump replaced recently, probably - I suspect - because it failed trying to haul petrol through this blockage. There is no evidence of gunk in the fuel pump itself, nor even (possibly) in the filter - but the "sock" filter at the fuel tank outlet does have stuff in it.

I have no idea what this black stuff is, but my guess is that if the tank is cleaned out, fuel lines cleared, filter replaced, and the failed fuel pump replaced, there isn't going to be any more gunk-related trouble, although the garage owner is being very careful not to guarantee there won't be problems - natural professional caution, I think.

The car is a shitstick, and not cosmetically lovely, so I am inclined to be a bit dubious about the idea that they're scamming for a resale car here - more likely is that it's a bit of a heartsink job that they want shot of, and don't want any more grief than they can manage.

I'm intrigued as to the likely source of the gunk - one thought was that if the fuel tank had ended up with much water in it, it could be a corrosion product? The problem appears to be progressive - my friend was finding that the car wouldn't run when the tank was less than ¼ full, but that has gone up to not running with it less than ¾ full now - that I find intriguing.

But I am recommending that she pays the (not unreasonable) £180 to get the tank flushed, lines cleared, etc., and takes a bit of a chance on the possibility that there is no other harm.
 
Thanks to all for your helpful ideas so far - some really useful thoughts (and anecdotes!) in there. I didn't know about the 2007 fuel contamination thing, either!

I am hoping this actually turns into a non-event, but I shall keep you posted...
 
I put a bag of supermarket granulated sugar in the tank of my dad's xjs and he needed a new engine within a week. That was in around about 1982, no not sure exactly whether it was a kilo bag or some old money measurement. Also obviously unsure of whether the tank was full/empty. All I remember with certainty is that it smelled of toffee.
 
contadino said:
I put a bag of supermarket granulated sugar in the tank of my dad's xjs and he needed a new engine within a week. That was in around about 1982, no not sure exactly whether it was a kilo bag or some old money measurement. Also obviously unsure of whether the tank was full/empty. All I remember with certainty is that it smelled of toffee.
Click to expand...
So it made it through the fuel filter, then...

I can't help but wonder, though - what made you do this? :)
 
I always thought sugar in petrol tanks fucks cars up. Remembering that bit in Day of the Triffids. Or was it Z for Zackeriah. Just old carberetta cars then
 
xenon said:
I always thought sugar in petrol tanks fucks cars up. Remembering that bit in Day of the Triffids. Or was it Z for Zackeriah. Just old carberetta cars then
Click to expand...
Looking around, it looks as if, if it does get past the filter, it can be a problem - blocking injectors gets mentioned.

I'm not sure how crystalline sugar would get past a fuel filter, though.
 
xenon said:
Caster sugar maybe? Still improbable granted.
Click to expand...
The more I think about it, the more I think that they saw "gunk in fuel tank...hmm, what do people put in fuel tanks, ah, sugar, this must be sugar". Bit of a diagnostic failure zone there - though they were right up to "gunk in fuel tank" :)
 
existentialist said:
my friend was finding that the car wouldn't run when the tank was less than ¼ full, but that has gone up to not running with it less than ¾ full now - that I find intriguing.
Click to expand...
I had something similar with my last car. That turned out to be down to a corroded pickup pipe in the tank letting in air once the tiny holes were above the level of fuel in the tank.

Thankful that was easy enough to sort myself. Prior to that I'd had a mobile mechanic out to look at it (as I didn't have time and the weather was shit) and they diagnosed a knackered fuel pump after barely looking at it :facepalm:
 
Fuel can be contaminated by stuff from the engine debris rust etc,stuff from the fuel (the fuel you brought was contaminated) and a few other causes there is even a fungus that loves fuel if the car has sat around for a bit might be that.
 
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