Log XLVI - What can you find in the fuel tanks

In my previous post, I mentioned about the loss of engine power i.e. low RPM, and suspected that it might be the bacterial in the diesel that was causing the problem. The Volvo Penta mechanic was very professional and kind to advise me a cheap and effective way to find out the cause.

The test method is to simply use an alternative source of diesel instead of from the fuel tanks. If the engines can operate normally with the alternative fuel source, then we can be very sure that the fuel is the culprit.

Here was how the preparation went. Firstly we had to get a small fuel tank and some clean diesel from the petrol station. I thought this was an easy task, so I just picked up any plastic bottle I could find in the marina and drove off to a petrol kiosk. When I squeezed the pump trigger for the diesel to flow, nothing happened. Then I found out that the pumps at our petrol kiosks will not work if we are not pumping directly into our cars. The petrol kiosk attendant told me that I had to purchase a metal tin to buy diesel in order for it to work. By the way, Esso does not sell metal tins but Shell does.

I was quite confused. What is the difference between pumping into a plastic bottle instead of a metal tin? Anyway I just followed the attendant's instructions. This time when I squeezed the trigger of the pump, diesel started to flow out into the metal tin! Somehow there is some kind of mechanism in the pump that can differentiate the material of the container. It can only start pumping fuel when it detects metal.

After getting my alternate fuel source, we went back to set up the new fuel system on the boat.

The tin can full of diesel was secured tightly using two elastic bands. A fuel hose was inserted into the top opening and sealed with tape to prevent spillage. After setting up the new fuel source, we went out for a sea trial. The engine's performance was great! In fact it was much stronger. We were able to pick up speed faster and could achieve a higher top speed. The clean diesel really made hell lots of difference, together with the new turbo charger.

Now we had concluded that the problem lied with the dirty diesel, the next step was to make it clean. We thought of several solutions of how to clean the fuel tanks. Drill a small hole at the bottom of the fuel tank to let the diesel drained out - but this is too dangerous, the drilling might trigger an explosion. Cut a hole at the side of the fuel tank big enough for hands to go through to clean the interior - but this operation is too time consuming and costly. Eventually we decided to pump the dirty diesel out from the small fuel sender hole on top of the fuel tank and see how clean the diesel we could make achieve.

We inserted a hand pump through the fuel sender opening and push the inlet pipe all the way to the base of the tank, so that we could reach any debris or water which would be at the bottom. This was what we pumped out.

Unbelievably dirty. From far it even looked like mud. And if you take a closer look.

You can only see a thin layer of polluted diesel floating on top. The bottom dark layer was actually water mixed with the bacteria sludge. I was surprised that the engine could even work at all with this kind of mixture!

So we kept pumping until we could see the golden colour diesel.

As we had to properly dispose the dirty diesel to a designated area in the marina which is about 500 meters away, we had to use small 20 liters containers to store the diesel for easier handling. After every four full containers, we had to carry them to the disposal point to empty them and repeat the process again. We made three trips altogether which is equivalent to twelve containers which works out to be more than 200 liters of diesel!

We were unable to achieve the pure full transparent golden colour diesel but it looked much better. After that we changed all the external fuel filters and all the engine and generator filters. It sounds tedious? Yes, it was.

We did a sea trial the following day. With only two passenger load, almost empty fuel tanks and most importantly clean diesel, Artemis 1 was flying during the sea trial. And so it closes the chapter of the case of the dirty diesel... for now.