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Diesel Fuel Problems Part 1.


Our problems started when we filled up with diesel in one of the Islands West of Italy. Around the world, especially in smaller places there are often fuel stations where they sell to both cars and boats. This station was one of those. It was on a road alongside the quay and served cars one side and boats on the other, from the same pumps.

We had heard that Bio fuel was being added to most diesel in Europe, but like most sailors and the authorities, did not realise the problems that would result from putting it in our tanks.

Within a few hours after the fill up, the engine started running strangely. Suddenly slowing then picking up again and generally running rough.

A filter change did little to help and eventually, several anchorages and much head scratching later, Ti Gitu was in the very deep anchorage at Capri. Several boats started to drag anchor as the wind changed, which quickly included us. The crew of an enormous motor boat scrabbled around with fenders to hold us off as we dragged and we just missed them. They did enquire about our engine and kindly offered us a tow but by then we were passed and so quickly hoisted sail and sailed out of the anchorage.

Ti Gitu gently headed East and I attempted to fix the problem. It totally baffled me. I tried everything I could think of, eventually giving up on fixing it at sea.

Looking at the chart we saw that Salerno which is a big commercial harbour was an overnight sail away. There would surely be a diesel workshop there. In the strong breeze we made good progress until the wind turned off in the middle of the night. That was when we really appreciated our junk rig which by holding the sails flat allowed us to sail very slowly on, sometimes just making half a knot. But it was progress.

Realising that despite Salerno being an enormous harbour we may have problems entering, so we telephoned our insurance to let them know what was happening and seek advice about the possibility of them covering us to be towed in.

The lady at Piatkus was marvellous, giving sound advice and yes we were covered and would we call as soon as we were safely in harbour.

What a farce followed, but that is another story. We did get in at about eight in the morning and telephoned to let Piatkus know that we were safe.

By pure chance Mo asked what we were covered for and we found that if - as by then I was suspecting it was bad fuel then we were covered for everything except replacing the fuel.

Our next problem was that it was the holiday season and Italy had virtually closed down for the month.

Due to the holiday it proved impossible to have things repaired locally so Piatkus covered us to have a replacement injector pump flown out from the UK and for injector servicing and tank cleaning.

This did not entirely cure the problems, although things were better and I started researching what could possibly be wrong.

What I found is that there are enormous problems with adding Bio fuel to Diesel. So much so that the UK government has acknowledged this and it is now possible and perfectly legal to buy and use Bio free diesel in sea going craft in the UK. This is known as FAME FREE fuel and is the only fuel that should be used in sea going craft.

To find out the type of problems that will be caused by this Bio Fuel read part 2 of this section.


Diesel Fuel Problems Part 2.


Continuing what BIO fuel can do for us boaters - first I want to explain what has been happening in recent years.

The authorities want to reduce pollution and make the dwindling stocks of oil go further. In an effort to achieve this they have reduced the amount of sulphur in the fuel to reduce pollution. Also to make world fuel stocks go further a proportion of BIO fuel has been added to Diesel.

The BIO part is renewable as it comes from various crops which can be grown. When prepared to be added to the diesel it is known as FAME (Fatty acid methyl esters). In general use the diesel supplied for road use is likely to have 5% but can have up to 20% of this FAME added.

It has been recognised that this can be harmful to engines and is considerably more difficult to store than normally refined diesel.

This is a shortened list of the problems that boaters are likely to find by using low sulphur FAME - and some solutions I have found:-


1/ Diesel injection systems, especially older versions, rely on sulphur for lubrication. Therefore increased wear can be caused by low sulphur fuel. Many people are adding 2 stroke oil to their fuel to overcome this. We now add 2 stroke oil at the generally recommended ratio of 1 to 200 and when not added we notice that the engine does not run so smooth. ( I have read a paper from a German university who found that of all the additives available for diesel fuel, 2 stroke oil is very effective) Please read the page about two stroke oil as there is more than one type and it is imperative that the correct one is used in both your outboard and diesel fuel.

 2/ FAME causes some rubbers such as fuel lines and O rings to soften, swell or harden and crack. This was the problem with our injector pump, a pair of small O rings had swollen and partially jammed a tiny valve. We now carry several spare O rings. It has been seen to melt the fuel pipes on some older engines.

 3/ Free methanol in FAME corrodes aluminium, Zink and some other parts sometimes found in injection systems.

4/ It can cause increased blocking of injector nozzles.

5/ Water dissolved on the fuel can cause a reversion of the fatty acid which will block filters.

6/ There will be an increase in the DIESEL BUG as FAME supports the various types of bug much better than normal diesel.

7/ There tends to be more sediments which will cause filters to block quicker.

8/ The FAME tends to break down any crud which has formed inside the fuel tank and hoses / pipes etc. This causes quicker filter blocking.

9/ There can be a high volume of particles which can sediment and block filters. Solid impurities can also increase wear.

10/ It can have a high viscosity at low temperatures which can cause overheating especially in distributor type injector pumps. This was also one of our problems.

11/ There are problems with storing this type of fuel. Even commercial suppliers are recommended not to store it for longer than 6 months due to it going off and the BUG growing. This sort of makes a mockery of using it in a boat where it is likely to be unused over the winter. Some suppliers are now recommending that instead of keeping your tanks full over the winter they are left empty.

The actual list is considerably longer than these main points show what a disaster it can be for a boat engine, especially the older engines of which there are many.

As a surveyor I try to keep abreast of the latest safety developments and about 5 years ago I replaced all the fuel lines on Ti Gitu with the latest EC RCD approved fuel lines. I now find that there can be problems with some of these and if you are replacing yours it may be worth asking the manufacturer if they are suitable for FAME fuel. (Just in case you take some aboard without knowing)

I do not know what is happening about this problem in the Mediterranean and Caribbean where I do know most suppliers are adding FAME to the road fuel, however it has been recognised as a major problem in the UK and now many marinas have approached their suppliers and are receiving FAME FREE FUEL.

(September 2013. I have recently been informed by Roland who is sailing through the Med that in Spain the amount of Bio (FAME) included in diesel has been reduced to 4.3% due to the problems caused with its inclusion. It appears that in Italy the amount is still 7%. In the UK the government has approved FAME free fuel for marine use and that can now be purchased in most marinas. But check before purchasing.)


I would like feedback from anyone with information in other countries. Just post a comment on my blog or email me please.


I have spoken to marina managers who have said that they have difficulty with some suppliers who seem to know nothing about FAME FREE FUEL. One marina manager actually found that despite being assured by his fuel rep that he was being supplied with the correct fuel, he later found that the company knew nothing about it and were supplying normal road fuel.

The engine manufacturers are worried about FAME to the point that several are saying that for most of their engines, if it is found that fuel with more than 5% FAME is found to have been used then any guarantee / warranty is void. BEWARE.

I am unable to prove this but it appears that engines with distributor type injector pumps are the ones most at risk. This will be because there are various 'O' rings inside them which are affected by Bio Diesel. The other pump types do not rely on rubber for seals so are less likely to be affected.

I have approached a number of suppliers for a reasonably simple kit to test for bio in your fuel. Although there were some kits produced they proved very ineffective. Some of the reason for this is that apparently because the BIO will stratify within the fuel, which to my mind means that at times your engine could be running on fuel with a very high content of BIO. The only real tests for BIO fuel must be carried out in a laboratory.

So in summary, I suggest that all boat owners with slightly older engines (roughly older than around 2006) make absolutely sure not to take on any FAME fuel and even those with the very latest engines which should be OK with FAME do not store the fuel for long.

Also it may be a good idea to carry a good supply of fuel filters.

Perhaps asking your engine manufacturer of any potential problems may be wise. If they respond please let me know what they say.


Happy sailing.