Sailing around Australia; Fighting Frustrating Fuel Fungus

4/4/2014 Fighting Frustrating Fuel Fungus

Our sailing around Australia adventures aboard Easy Tiger have brought us to Port Lincoln where we hoped to get quite a few nagging problems sorted out.

Several attempts have been made to diagnose the problem that has been causing the port motor and recently the Starboard motor to stop from time to time, usually when we least wanted them to.  A mechanic in Mandurah was paid $700 to replace the port motor fuel lift pump. The engine ran for ten hours after the cheque was banked and stopped again.

Next it was decided that the breather in the fuel tank might be blocked. Unable to access the breather without major deconstruction of the boat, we drilled a hole in the tank inlet pipe. Again the engine ran well until we were half way across the Great Australian Bight.

When either of the engines stopped it was just like they had been switched off. Then after waiting several minutes, we would be able to start them again and carry on as if nothing happened for another hour or so.

The fact that they would start straight away without having to bleed the fuel, started me thinking that perhaps fuel was not the problem.

After we had to be towed in to Streaky Bay with only one operating engine, I did another investigation. I remembered that someone told me about fuel fungus that boats in the tropics suffer from.

Fuel Fungus. We researched this on the internet and found that in each diesel tank, there is an amount of water.  The water is created by condensation in the air contained in the tank. Diesel floats on water so the water created by the condensation sits in the bottom of the fuel tank. In between the water and the diesel a fungus can grow, given the right conditions.

Biocide can be added to the fuel tank to kill this fungus. The dead spores then float into the diesel. This means the spores are caught in the filters. While in Streaky Bay we added the biocide, then planned to change all our filters every ten hours, to remove the fungus killed by the biocide.

After motoring and changing a set of filters on the way, we are tied to a floating jetty in the Port Lincoln Marina. The first thing that we noticed is that the fuel filter elements looked like they had been coloured in with a black marker pen. There was very little or no particles or dirt in the water traps at the bottom of the filter.

Next we pumped the remaining diesel (in this case over 80 litres) out of the tanks and disposed of it at the appropriate waste centre at this marina. Fortunately, our Fusion 40 Catamaran has large tank inspection lids in the floor enabling us to get a torch and one arm inside.  Once the tanks were pumped out we sponged and wiped out the residue.

The surprises here were that half a cup of sludge, half way between black and dark coffee in colour, was picked up out of the tanks. Also, we located the fuel pipe pick up strainers that were inside the tanks. Both of these were clogged with the same sludge.

We rolled around on the floor, trying to bend our arms at very un-natural angles to wipe the tanks out thoroughly, then wash them with warm soapy water, then dried the tanks. We then left the tanks open for a day to try and dry them out further.

While the tanks were drying we inspected our four jerry cans that we use to store extra fuel. By holding them up to the light, we could plainly see black spots on the walls and in the bottom. Again a rinse with clean diesel, seemed to clear them of any obvious. A tea spoon full of Biocide was added to each jerry can.

Next step was changing the primary fuel filters for each engine, as well as the secondary or fuel pump filters that are above the fuel lift pump on our Yanmars.

Refilling the tanks, we used a very fine strainer between the jerry can and the tank inlet. Our tanks hold 180 litres each side, so with five jerry cans, 4 trips in the dinghy to the other side of the marina then a couple of hundred metres walk to the service station, were completed. We didn’t need to go to the gym to get exercise that day.

The tanks were completely filled, lessening the possibility of condensation. The finishing touch was pouring 100mls of Biocide into each tank.

Hopefully we have won the fight against frustrating fuel fungus and we are ready for trouble free motoring. Some wind in the right direction would be nice too.

The filters at the top have done 10 hours. A new filter as a comparison is at the bottom of the picture.