A clean tank is a prerequisit

Later in 2014, I decided to build a fuel polish system and did cycle the fuel for a couple of hours through the fuel filter. I removed the fill hose and reached in the tank by using a copper tube. After three hours, the filter still was in a perfect condition. I was happy, because the state of the fuel filter made me believe, that the tank should be fairly clean inside. But I was still unsure, whether the tank and the fuel inside were really clean. Whenever we returned from a daysail, I found some black and brownish stuff in the filter bowl.

During the preparation for the planned cruise in June 2015, I thought, that I would give it another try with the fuel polishing, just in case... But this time, I did remove the tank sensor and entered the tank just next to the pick up line. Everything seemed to be fine, until the copper tube touched the bottom of the tank.

The filter turned BLACK! Once the bowl cleared up a little bit, some quite sizeable flaky stuff became visible. Shortly after reaching the bottom of the tank, the whole filter was full of this flaky something and clogged up badly.

The clogged fuel filter

That was the moment, when I decided not to leave the dock anymore, before the thank got cleaned thoroughly. I called in a professional fuel polishing company to complete this job.

Two days later the fuel polishing company came to the dock. They basically did the same thing I did. They accessed the tank through the sensor opening. But they have a lance to evacuate the fuel and run it through the filter, and on the other side they have a lance, injecting cleaned fuel under pressure. This makes the big difference to what I could do. The pressurized washingwith clean diesel fuel removes dirt, algae and what ever found it's way in to the tank.

It took them about 90 minutes to clean the entire tank. Even with their large filters, their system got clogged up after a few minutes. They had to change the filter three times unless they could finish up the job. Another benefit is, that all water and bad fuel, algae etc. got evacuated.

I could take a look at the amounth of algae which has been pulled out of the tank. It was almost a full bucket of algae and dirt - really scary!

The fuel polishing company provides a three year warranty for their job. If I add clean and ethanol free fuel and treat it with additives, in the near future no growth should occur.

I'm happy that decided to have the tank cleaned. Now I feel very confident, to not suffering from a dying engine because of bad fuel and clogged filters.