Low Cost DIY Diesel Fuel Polishing – Ep 13

They say that sailing costs as little or as much as you want it to. In this episode of Sailing With Thankfulness we show you how we clean our diesel fuel and fuel tank for ultra low cost and without the need to construct a dedicated fuel polishing system. We improvised and came up with a very low cost way of clearing out the diesel bug, polishing our diesel fuel and making sure our fuel tank was clean.

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Also see episode 52 – DIY Fuel Polishing Part 2.

Episode Notes

0:00 Stephen

We know we’ve got diesel bug. To have confidence in our fuel system we want to clean our fuel. The usual way of doing this is to polish it and to polish it we need a pump, a filter and a water separator. We’ve been to numerous marine shops looking for these parts and they’re not available anywhere. We can order them online but that’s going to take at least a month and we don’t want to wait a month before we go sailing again.

Our Low Cost DIY Diesel Fuel Polishing System

0:27 Stephen

So, we’ve come up with an idea to pump the fuel out manually through the filters that are already on the boat and see if that works. We’ve got one of these manual fuel transfer pumps. It only does four litres at a time and we have 150 litres so it’s going to take a while (In practice it only took 2 hours to pump 100 litres.)

We’re going to manually pump out the fuel into containers like this and also some seven litre water bottles. It’s all a bit cumbersome. It’s going to be slow but, at the end of the day, we’ll have clean fuel and be able to sail with confidence. We also have some spare 10mm fuel hose and some 10mm and 6mm clear hose. Our aim is, with all these bits and pieces, to be able to make a system that works.

Utilising Existing Boat Parts

1:16 Stephen

We’re looking at the existing fuel filter and water separator for the motor. This black fuel hose then goes to the strainer which connects to the lifter pump. I’m going to take off the strainer cover and attach another hose to that black fuel line and then connect the manual transfer pump. I’m doing the clamp that keeps the strainer lid on now. I’m using the 6mm hose and we’ll clamp that on. It’s nice and tight.

So hooked up to the manual pump we have the boats fuel filter and water separator, the boats fuel line coming into a plastic hose and then into the manual transfer pump.

Using The Fuel Polishing System

2:38 Stephen

Here we go. Let’s see if the experiment works. I can hear it and I can see it starting to fill up. We’ll also be able to see if there’s any water coming through.

The good thing is that this manual pump works under a vacuum pressure so having pumped it a few times it will continue to fill up without pumping it and I just give it a few extra pumps if I need it to go a little bit faster but I can have a rest.

That’s 2 litres, 148 to go. Just before it gets to the top we’ll release the pressure in the vacuum so that we don’t overflow. Let’s switch off the fuel valve. Our issue now is we’ve got fuel in this line and we don’t want fuel going everywhere when I disconnect it. We’ll have to work out a little system for that.

For the first 4 litres I’m going to empty it into a clear dried out water container so that we can check the fuel to see if there are any more contaminants visible and if any water has come through. I’ve emptied all the water into the water tanks. The next step is to dry out all the bottles completely. We don’t want to be putting water back into the fuel. Just got to get those last couple of drops of water out.

How Clean Is The Fuel?

4:10 Stephen

We’ve pumped out all of the fuel. I’ve got about 95 litres and I’ve just taken off the fuel filter and the water separator. I first drained all the fuel out. basically that’s clean in there and the only bit of gunk I can see is that tiny little bit on the top of the filter. The filter itself looks pretty clean after having 100 litres go through it so I’m really happy with that.

This is what came out of the water separator and you can see that it’s all fuel. If there was any water it would be on the bottom so that’s more good news.

Cleaning The Fuel Tank

4:50 Stephen

We’ve been successful in extracting all the fuel through the fuel filter. It’s looking really good. Now I’m going to reverse the process and use my manual transfer pump and put this down inside the fuel tank through the sensor hole and extract the last little bit. I’m expecting this to be a lot dirtier than the other fuel that we’ve got out. There we go, down below.

All right, so this end goes down into the bottom corner of the tank. This is literally the last little bit. This is great fun. It’s an improvisation project. I needed something rigid so I could poke around in the bottom recesses of the tank and I found this old piece of fishing rod. I put the tube through the first big ring, a bit of tape around so I’ve actually even got an adjustable pokey around thing. Improvisation is a great skill.

6:22 Kerry

Well done.

6:24 Stephen

To help clean the tank, to the end of a piece of fishing rod I’ve used duct tape to attach a rag which I can then put down through this 50mm hole and just move it around inside and see just how dirty it is and whether we need to do something more significant or whether this will be sufficient. Just with that few seconds there’s very, very little. A few little brown specks but hardly anything. We’ll give that a good moving around and we should be done.

That 50mm hole makes it really hard to see inside the tank. I have had a bit of a look though and everything that I can see is perfectly clean. I can even see the feed for the fuel to the engine at the bottom of the tank and it’s all completely clean so I’m really happy.

Comparing Fuel Filters Before & After

7:38 Stephen

This is the filter that I installed about a week ago and we just put 100 litres of fuel through it to clean the fuel. If I shine my torch up through the middle of the filter you can see the light coming through to the outside of the filter which is a good thing. Compare that to the filter that we took off. This was completely covered in diesel bug. When I shine the torch up through the middle there’s nothing but darkness around the edge. It’s completely clogged. Time to throw this one away. The other one may have a little bit of life left in it but given that we put 100 litres of fuel through it we’ll just check it every week or so.

I’m so pleased with how this turned out and I’m so thankful to all of the people that helped me and gave me advice – really, really thankful. It was so great that we were able to do it with so little resources. The only thing we really bought was the manual transfer pump which was about AUD$100, a piece of 6mm hose, an old fishing rod and a rag and that’s it. That was a great result.

I’m going to celebrate with a piece of chocolate brownie. Oh, so good!

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