How to Clean a Diesel Fuel Tank
I know you will get plenty of good help but I wanted to give you a quick idea of what I went through last year. The 30 I bought has not been used much for some time. I will try to contain my info to the tank only. Mine had quite a bit of blackish alga in the tank. I removed the float, which gives you a hole in the top of the tank. I used a kerosene pump (the plastic kind people use for transferring from a 5 gal can to their heater.) I removed all I could this way. I then put in a 1/2 or so of new clean diesel, rocked the boat and pumped it out. I then took a flat piece of spring steel and wired a scrubby (scotchbrite) to the end of it. This will fold up to go through the hole then spread out again. I tried to get to every surface in the tank. After this I again put in 1/2 or so of good fuel and rocked boat and pumped out. After looking around inside with a small flashlight you can see how you are doing. I'm also told there is a screen on the fuel pickup. Most people suggest removing this. I blew back through mine to make sure it was clear and left in place. After making sure the tank is mostly clean, there is a product you can buy that will dissolve the left overs and send it on through your fuel system (I'll look it up, if you want). Of course, you need to then change filters and etc. Hollis on Lake Guntersville
I purchased my 1986 C30 this past fall, and found a great deal of sludge in the tank, and a very clogged filter. Removing the fuel-sending unit allowed me to inspect with a small flashlight. There was no question that the tank needed to be cleaned. First I went to Home Depot, and purchased a $14.95 pump that attaches to a power drill. Next I vacuumed the tank using this pump (Diesel fuel is safe to use with this type pump, NEVER TRY THIS WITH GASOLINE!!!). It was amazing how much sludge the pump picked up. Using several clear 5-gallon jugs, I transported the old fuel home, and after letting it settle overnight, I pumped all but the bottom half inch of fuel into my home heating oil tank. Next I back flushed the fuel feed line to clean the screen. Lastly, I took a coat hanger with a lint-free cloth and scrubbed the tank inside as much as possible, completing this before all the old fuel was pumped out.
As a final safety measure, when the tank was empty, I poured in 3 gallons of fresh fuel, and vacuumed it out with the pump. Again, more sludge.
The real success of this project was the pump. The high volume of it really creates the needed suction to remove all the sludge, right down the bottom corner of the tank. The clear plastic tubing that comes with it allows you to monitor the amount of sludge being removed. As a side benefit, this pump is outstanding for pumping waterlines and water tanks dry during winterization, cleaning out bilges etc. I will carry it on board with a cordless power drill this season. Stephen Bradley, WINDSWAY C30 #4567
Take the darned screen off.