Saturday, July 5, 2025

The dreaded diesel bug. Part 2 - The fix (I hope)

I'm feeling rather please with the decision I made to replace the bladder tank, which would probably not have been cleanable and would certainly have been very hard to do if it was. Also how I fitted the replacement, I feared a very difficult job in cleaning the tank because I was not sure the access would be good enough and particularly getting the inspection hatch off with the pick up tube being quite long, it came with the pick up tube installed and I was not sure if it could easily be removed with the cover in place. Moving the tank is possible but a major job, even with over 30 Kg of fuel in it pumped out. 

I need not have worried, with the breather and fuel return pipe removed and after a struggle to slacken the fore and aft restraining strap the cover came off easily and I didn't even have to disconnect the fuel line which later saved a lot of pumping to get air out of the system.

The fuel tank on installation, the priming bulb didn't work and was
removed - the low pressure fuel pump not being strong enough to
open the non return valve. Note how close the top of the tank is to
the cockpit seat, the fuel pick up mounted on the inspection hatch
extends to within a few mm of the tank bottom.
When opened I could see the bottom of the tank on the outboard side that looked pretty clean but when I took some pictures the inboard side that wasn't - it was awkward pressing the icon to take the shot whilst holding the phone and lamp, these are the best pics I could manage:

Dead diesel bug on the inboard side looking
forward. The fuel was largely white diesel with
some red and a small dash of green which made
looking through it much easier than if it had been
all red. A minor contamination compared to many
but still needing to be sorted.
And looking aft.
The bug had generally been broken down but not into small enough pieces, there was a couple of clumps an inch or so across and a few small strings (bottom right in the picture immediately above and on the next).

I pumped out the first 20 litres or so, filtering it into clean cans, and being careful not to disturb the debris. I then used the pump to suck up much of the gunk with the remainder of the fuel into a separate sacrificial spare can. This got rid of the majority of the rubbish but left some:

After pumping.
The rest of the fuel and dead bug were then mopped up with kitchen roll.
Almost done.
Finished, unfortunately the pic showing the cleaned
area around the fuel sensor was too blurred to reproduce.
I then refilled the tank, gave it another "shock" dose of Fuelset and the engine started immediately and ran for close to an hour without needing to bleed the system, I'll be sure to run it for a bit longer next time I am down to make sure it is not going to conk out as I leave the marina and will change the filters after a few more hours running to give any remaining particles time to get to the filters..

Fortunately the marina would take the contaminated diesel into their hazardous waste facility, some don't, along with the oil from my last oil changes.

Job done. I hope.