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FuelSure Diesel Misfuelling Prevention Device

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      17.06.2010 18:49
      Very helpful


      • Reliability


      Simple fuel cap replacement to prevent putting petrol in a diesel-engined car

      Warning: This opinion does contain several references to nozzles being plunged into holes, so anyone who thinks that the image of a train rushing into a tunnel is a metaphor should look away now and think of nice things like Shaun the Sheep or Lorraine Kelly.

      I do, however, make no apologies for referring to lady's bottoms - after all, they're what got me into this trouble in the first place.

      Clears throat. Ahem.......

      There are fewer things in motoring more bruising both to the self-esteem and even more so to the wallet than putting the wrong fuel into your car.

      Accidentally putting diesel oil into a petrol car has largely been eradicated since the adoption by filling stations of a narrow nozzle for unleaded petrol, with a correspondingly narrow fuel pipe on the car, making sure that a diesel nozzle just won't fit.

      Unfortunately for the ever-burgeoning numbers of diesel car drivers*, a narrow petrol nozzle will fit their car's fuel filler pipe so extreme vigilance is needed if a huge bill for repairs is to be avoided.

      (* In 2008, 45% of new cars were diesels and my current car was one of them)

      I'll come clean - I did this in an absent-minded moment in April 2008 with my first diesel car, which wasn't helped by the fact that our other car is petrol-engined and all the hoses at my local garage are black! Only the 'guns' and holsters themselves were colour-coded, somewhere in amongst the adverts for Pizza Hut that festoon even the handles of these things nowadays. With 'hindsight' (hah hah, very good Chris - 'hindsight', sounds like looking at bottoms), it didn't help that a lovely young lady clad in anatomically-correct Lycra shorts swept by on her racing bike.

      I might now be 60, but there's nothing wrong with my eyesight that Specsavers can't cure and a gratifyingly high proportion of my flesh is still willing too! T.M.I.?

      Fortunately it was only a 10% 'top-up' and I noticed nothing till 90 miles later after I'd swung off the M4 at the Swindon turn-off, presumably encouraging the petrol to slop around and in doing so, work its way to the engine. Passing Cirencester, I was alarmed to see an engine management warning light come on, and then to have the car, a 2.0 litre Citroën C4 go into what is known as 'limp home mode', i.e. gutless or "0 to 60 by Wednesday" as it's sometimes known. Unbeknownst to me, I'd already committed cardinal sin no. 1 - Turning on the engine at all after realising (or not in my case) my mistake, and worked my way well into the range of sin no 2 - actually driving the thing!

      The AA (Autoeroticists Anonymous?) was called out, the diagnostic box of tricks was plugged in and the error light was reset, with advice to give it 'some welly as these modern diesels don't like months of stop-start driving'. At no time was I asked if I'd put the wrong fuel into it, and to be fair, the tank still smelled of diesel. Miles later, nearing Gloucester, it happened again and so hours late I managed to get to our friends at about 30 mph using the Citroën's 'limp to Hereford' mode.

      Next morning I drove it in 'limp to nearest dealership' mode, having to my horror during the previous evening, checked the Shell till receipt in my pocket, proudly proclaiming '7 ltr unl'd petr'.

      Lucky I didn't 'give it some welly' on reflection.

      Yes folks I'd really gone and done it this time! I quickly joined an internet diesel forum overnight but soon wished I hadn't - the sharp intakes of breath were palpable as the forum seemed to be particularly well subscribed to by 'Jonahs', all of whom thought I'd need a new engine by dawn.

      Fortunately, the garages aren't quite so 'doom and gloom', and just set about the job in hand. A complete flush out of nearly 50 litres of tainted fuel (Hidden Cost No.1 - fill her up again at your own expense) was their first port of call, coupled with changing potentially damaged items like the fuel filter and a complete check-up of all fuel lines and the emissions system.

      With a wallet some £300-odd lighter plus the cost of a 60-litre fill-up all over again, I at least had a certificate in my hand to say that the car was still under warranty, which having done some reading around the subject, is more than you'd get from a BMW garage, who it seems would promptly deny/void everything and/or charge you five grand+ for a new engine.

      And the car? Well it ran fine for several thousand miles afterwards, but as it had always been a potential money-pit if it hadn't been for the extended warranty, I sold it in November 2008 in exchange for a SEAT Leon 2.0l diesel. In a quiet moment, I often wonder whether it fell apart on the next owner (but always with a relieved smile on my face!)


      Putting petrol in a diesel vehicle costs British motorists over £800 million a year in repairs and £100m+ in other expenses, and apparently I'm in good but red-faced company. 400 hundred of us do it every day in Britain, and even our local 'cop-shop' has been hauled over the coals for costing 'The Met' and therefore local taxpayers £7000 this year so far.


      Well petrol is an oil-based petroleum spirit, a volatile fuel and also a solvent.

      Diesel, whilst still coming from the same hole in the ground is a 'light' oil and therefore also a lubricant to some extent.

      In a diesel system set up to expect a fuel that also has some lubricant qualities, pumping a solvent into it is just asking for trouble. The plastics used for the fuel lines may not be resistant to a solvent, and items like the tiny ceramic aerosol nozzles of the fuel injectors could get worn away as the petrol tries to 'clean' them rather than sooth them and goodness knows what prolonged exposure to a solvent will do to the extremely high pressure fuel pumps delivering fuel pressures somewhere close to that experienced at the bottom of the Marianas Trench.

      I got away lightly but it has set me thinking. All it would take is another filling station with all black hoses and a slim girl wearing Lycra cycling shorts.................


      a) Try to put Lycra-clad lady cyclist's bottoms out of your mind. For me, not easy, I'll grant, especially now that I've committed the thought to paper.

      b) Given that a petrol pump nozzle will fit the larger diesel fuel filler, search the web for something clever using the unique width of the diesel nozzle to release your car's fuel filler cap, and this is how the three devices I've found work.

      Firstly there was www.dieselkeydirect.com. This boasted that it was the only product on the market to both prevent mis-fuelling and the siphoning off of your own fuel. However, their web-site didn't happen to mention anything as tacky as the price, preferring to get you to fill in an enquiry form. Sorry, but in this "I want it and I want it now" world of the internet, a site without a 'basket/checkout' system loses my vote even if they did have a good video.

      Next was www.caparorightfuel.co.uk. This was more like it with a sub-thirty quid price tag and something I can understand - a bright yellow fuel-cap replacement. A lid that will only open when prodded by a wider diesel nozzle which then unlatches all the requisite pressure points around its edge whilst a narrower petrol nozzle would only manage some of them, leaving it shut. However, you had to specify your car, which lead me to believe that it wouldn't be so easily transferable between vehicles. There didn't seem to be any way of opening it to fill it from a can either.

      Lastly, I chanced upon www.fuelsure.com. Their product worked in a similar manner to the Caparo, needing all of three latches to be pressed simultaneously by a wider diesel pipe. However what tipped me in its direction was its full set of screw and bayonet adapters, making it much more likely to be transferable. It also comes with an emergency tool to release the cap for filling from a can. Price-wise there was not a lot in it between the last two. Also, like the Caparo it didn't prevent siphoning, but there may come a day when you're glad it doesn't, and anyway, most car fuel caps are under a flap protected by the central locking system these days - mine certainly is.

      When ordering on-line, they do however ask you for your car's make and model/year, so I assume that this may have some bearing on the future adaptability of what they send you. Incidentally, their Paypal option didn't work - it kept telling me I hadn't yet completed my credit card details instead, so I acquiesced and paid by the same credit card that Paypal charges to!


      On opening the packaging you'll find, or at least I did, a screw adapter with the same thread as my existing filler cap and a selection of three other bayonet adapters covering what Fuelsure term as 'most cars and vans in use in the UK today'. The emergency tool for opening it when there is a need to use a 5 litre rescue can, also doubles as a kind of screw driver for fitting the first stage of the Fuelsure to the filler pipe - you'd be well-advised to keep this in the car.

      Removing your existing fuel cap, you attach the new outer flap to the inner using the flexible neoprene hinge supplied. This fits like an O-ring around both and then you screw (or bayonet) the inner to where your old fuel-cap used to fit.

      Another bit of advice I'd give which is slightly askew from the official instructions is this. Don't cut the retaining strap (if there is one) to your existing fuel-cap until you're happy that the new adapter fits. If you can get away with it, try not to cut it at all, and mine obliged by being stretchy enough to prise it away from the retainer without damage to the rubber loop on the end.

      The Fuelsure itself doesn't dangle loosely at all once opened so there's nothing to forget and drive away from! The lurid fluorescent pink of the neoprene strap that forms a hinge between inner and out parts of the cap is enough to shout "don't look at her bum, wake up and watch what you're doing!" although fortunately, the protection doesn't stop with a good talking to.

      To open Fuelsure, you have to take a single 'stab' at the cap with the diesel pump's nozzle - it's best not to have your fingers anywhere near the trigger at this stage otherwise you could end up dispensing diesel fuel all down your leg and other points south at your expense! This first contact releases the outer flap, and having removed the nozzle from it, allows the flap to fall downwards. You are then free to plunge the gun into the stygian depths of your fuel pipe.

      Once you've finished, you press the outer flap back in place with a satisfying click. It feels pretty solid, and I guess it has to be to survive being prodded with a metal pipe every few days and still survive its two year warranty period and hopefully, beyond. It also needs to be fume-proof enough to pass an MOT check, so don't forget to leave the garage mechanics the emergency 'stick' or put the original factory-fitted cap back on for the test.

      Oh yes, and don't wait till you're out of fuel before testing that it works properly!


      Anyone with an older car with an external filler cap, like my old MG Midget*.

      Not only would it not be lockable, since it would only need a prod from a diesel nozzle, but it's also fluorescent pink which I think you'll agree does not sit well with British Racing Green and would get even Gok Wan drummed out of the MG Owner's Club!

      (*Yeah yeah, I know. MG Midgets didn't have a diesel engine!)


      Fuelsure - an effective solution to the problem, and for £32.99 it's a bargain if it's going to save you untold expense in the future. I seem to have gotten away with it once, but there's no telling how much premature ageing of the fuel system you've set in motion, and I don't feel like tracking down the car's current owner to find out, strangely enough!

      Fuelsure also means I can let my mind wander to more aesthetically-pleasing things, which brings me neatly back to 'spray-on' Lycra shorts.

      I've made light of this, but hopefully I've nipped a further occurrence in the bud. Mis-fuelling is a growing problem, which started when unleaded cars could have their catalysts ruined by leaded fuel. The problem was solved by altering pump nozzle and fuel pipe widths and the 'baton' was thus passed on to diesel owners who were given no choice but to be careful. Not only does it cost you personally a lot to make a mistake like this but the tainted fuel which is then no longer of use to man nor beast takes a lot of reprocessing to get it to any state of usefulness, so it's an environmental disaster too.


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