Sorry,
but this is a bit of a pet subject for me... Can't help it, as I have had literally countless injection pump problems on vehicles I have driven in 12 years of working in very rural Ghana. We store about 150,000 litres of Diesel, which we buy from a reputable worldwide petroleum company. This fuel is brought from the refinery to us in a dedicated tanker, which is used only for us. Recently Ghana is forced to import already refined Diesel oil (mostly from Nigeria) and quality is very variable. I am sure this is no different in RIM or wherever in developing Africa. The problem is not the original refining, but every step of the supply chain, where there is contamination (deliberate and simply unnavoidable). Obviously when you get to drums in the desert you are down a pretty long supply chain... Therefore opportunities for contamination abound. Here a litre of diesel is worth about half of a day's pay (on minimum wage levels) so theft is also rampant. This problem exists all over Africa. The theft is ofen disguised by replacing the stolen diesel with water or Kerosine (depending on market prices of Kerosine Vs Diesel). Our experience led to numerous solutions comprising paste to dip tanks that highlights water contamination, to a final centrifuge which costs about $10,000 and spins diesel at very high revolutions to seperate particlulate and water contamination. The manufacturer of this centrifuge indicated that weekly cleaning would suffice - we ended up cleaning it every 3 hours!! Strangely different types of injection pumps seem to get on better than others, with Toyota leading the pack in terms of sensitivity, Nissan and Landrover seemed to do much better. Now if you are doing a once a year trip of a few thousand Kms then I am sure nothing will happen - as many suggest, just take spare filters and drain the water trap regularly. For extended travel or really long term I would recommend a Racor or Separ filter in addition, but definately with a small electric pump fitted also as suggested by Julian. The extra strain of more filters can result in reduced flow rate getting to the injection pump, resulting in less lubrication and cooling with dire results for the pump. All this effort of course ultimately hinges on the micron size of the element in your separ/racor/toyota or whatever filter... And finally it will not completely eliminate problems - just a fact of life in the not so developed world where diesel can be really crap! High sulpher content in fuel also means changing the oil every 5,000kms, and under mining type conditions Toyota recommend even dropping that to 1,500kms! And anyway, when the pump starts to go it is always very gradually... will generally appear as difficult starting when hot, higher consumption and big flat spots. Generally will get worse over one or two weeks, but won't leave you stranded.
But having said all that a dose of UK supermarket fuel might be just as risky :-)
Gil