Fuel tank question

[Nanoose]

In prep for the annual haulout I went to the boat to fire up the engine (hadn't in about 6 weeks), change the oil, etc. The engine fired right up but then stopped. Cranked well, nothing else. It's a diesel, one cylinder, Volvo MD 5. Had a fellow come out to take a look and, as suspected, it's a fuel problem. It would appear that I've got A LOT of crud in the gas tank and that has fouled most of the fuel system. Injector is being rebuilt as we speak.

So...my question is...I'll drop the plastic fuel tank out but, after it's out, what is the best way to clean it?

Advice is greatly appreciated!

Dave

[The Bigfella]

Depends how easy access is, how easy the tank is to move around, etc.

I've cleaned some crud-infested things by dropping in some old nuts (as in nuts and bolts type nuts) and giving it a shake with a bit of fuel in there.

You can also use degreaser and water - just make sure you give it a very good hose out and get everything out. That's how engines get cleaned down during rebuilds - hot-tanked, then degreased and hosed out, blown off with an air gun, etc. No reason not to do the same with the tank.

The other thing you need to consider is how to keep the crud out. It is often dead little critters believe it or not. If your tank isn't kept full, you can get condensation in the tank, the water settles at the bottom of the tank and IIRC it is either an algae or bacteria (or both) that feeds on the boundary layer between the water and the diesel. As this dies off, it falls to the bottom of the tank. There was literally gallons of this mud in the bottom of Grantala's original tanks when I removed them after 65 years.

The downside of keeping tanks full is that you can end up with stale fuel.

That's why I went to 6 smaller tanks in my boat. I can use 2 as day tanks and not fill the others unless I am going long distance. No stale fuel, no condensation problems. (I gave away 600 litres of old stale fuel when I replaced my tanks)

[soba]

Only thing that ever worked for me was steam cleaning. Anything else with a plastic tank, and the algae that fouls your diesel could remain...even a tiny bit...and then return. Steam clean or replace everything from the tank to the racor/fuel filter to eliminate that stuff. Diesel conditioner that kills off the algae works too.

I used to have terrible problems on my Island Hopper in this regard. I finally found a tank with a horizontal bottom baffle that had small holes in it...the water and the algae would collect under the baffle, and it was easier to drain the gunk all out. I finally traced the problem to my diesel supplier, who had an old grungy algae infested tank. Glad I don't have to buy from him anymore!

[Nanoose]

Thanks for the advice!

I'm going to go with the degreaser method. Deb and I spent a couple of hours working on getting the old tank out and I've decided that when and if there is a next boat it will either a.) be small enough for an outboard or, b.) big enough for a walk around engine room.

To get to the tank meant I had to go through the access hatch in the cockpit sole, upside down, while the engine dug into my back. This would've been no big deal a couple of decades ago but made me feel my age today.

The clamps are off the tank, the supply and vent lines have been uncoupled and all that's left is to remove the fill line which, of course, requires a wrench I didn't have at the boat...

I'm really glad we didn't have a camera today.

Dave

[jimmy]

My tank had a strange kind of yellowish build-up/deposit on the sides and baffles. I'm not sure if a stronger chemical would have got this off or if it even would have been a problem, but I cut two extra access hatches in the top of the tank and used a variety of tools (mostly variations on wire brushes) to get it all off. Next time I think it will be easier to just make a new tank.