Fuel Tank Cleaning

cat38skip · Jul 15, 2009

I had a similar problem with the fuel & tank on my Catalina 38. The sludge had built up in the bottom of the tank to the point where it clogged the fuel pickup and the engine died. Oddly enough, the filters were doing ok and not gunking up beforehand. I used an air pump to force the crap back out of the fuel pickup and was able to run the engine. I have switched to a 6 gal portable tank until I can get up the nerve to get into the main tank and clean it out.

Neil McDonald · Jul 15, 2009

Before you do anything else, go out and buy a plastic turkey baster and attach a foot or so of rubber hose to the end of it. Remove the fitting on the top of the fuel tank where the discharge hose connects to it. This fitting should come off with a straight pickup tube attached that reaches down to with about an inch or so of the foot of the fuel tank.

This gives you access to the tank to use the turkey baster to take a fuel sample by sucking up some fuel from the very bottom of the tank. Then dump the contents of the baster into a glass jar and look for signs of either gunk or water in your sample. If any appears you either have to develop your own method of removing and cleaning the tank contents or you have to go out and pay quite a lot of money for a fuel polishing service to do it for you - check the ads in Pacific Yachting or ask at your marina.

Most important. While you have the fuel pickup tube removed, use a suitable nail to destroy the filter screen that was originally inside the foot of this tube....if it is still there. You want the Racor or other regular screen to catch any stuff that accumulates. THis is because you can easily change fuel filters at sea.... but fiddling with the pickup tube is much more of a challenge.

You should also look at your primary filter for signs of water or gunk.

Good luck. Let us know what you find.

BobM · Jul 16, 2009

I presume you know that you aren't overheating.

RichH · Jul 16, 2009

First off, draw off some fuel from the tank, put it into a clear glass and hold the glass between your eye and strong white light. If you see/denote any 'haze' in the fuel it probably indicates that you have a fouled tank - fungus/bacteria infection. Small tanks foul easily, especially if the fuel is not used often.

Do check for an obstruction in the 'dip tube' (tube that 'sucks up' the fuel from near the bottom of the tank) ... could be the 'dip tube screen' on has become blocked with 'crud'. Also check to see if the tank vent is obstructed (mud dauber wasps 'love' to build nests in the vents).

Check to see if there is a large bio-mass growing on the inside tank walls ... just take a long stick/wire pushed through the dip tube hole ... and rub the stick, etc. on the walls, withdraw it and see if any 'gunk' is adhering to the stick ... if so you need to CLEAN out the tank. If the tank is fouled (haze in fuel or 'gunk on the stick'), the 'best' remedy is open the tank access port and hand scrub the internals ... or empty and remove the tank for proper cleaning. "Fuel polishing" will NOT remove the bio-mass, etc.; and, if the biomass, etc. isnt removed it will most certainly 'slough-off' from the tank walls later and during the worst sea state conditions possible. Adding 'bacteriostat/anti-fungal' compounds to a grossly fouled tank is very risky - as it may totally loosen the bio-mass and overwhelm the Racors, etc.; if the biomass is 'slight' the bacteriostat 'may' have sufficient ability to keep the 'bio-cells' in suspension ... but you WILL use a lot of expensive filters.
Once the tank is cleaned (hand scrubbing with a stiff brush, steam wand, or power washer wand). Any fouled fuel that you remove from the tank .... take it home and burn it in your home heating furnace.

Start with a clean tank, use 'fresh' fuel (from truckstop, etc.), keep only the amount of fuel you NEED plus a little 'reserve', (if possible) drain the tank when long term storing the boat / dont keep the tank 'topped off'.

other applicable thread: http://www.cs-bb.com/forums/CSBB/index.cgi?noframes;read=150893

hope this helps

MoonSailer · Jul 16, 2009

Never keep your tank full especially over the winter. There is no advantage to using old fuel. It also takes time to grow a biomass. With fresh fuel there is less time to grow. It seems that the ultra low sulfur diesel would be better to prevent growth. When they are getting rid of the sulfur they also remove nitrogen and other nutrients that all life needs to grow. Nothing can grow without phosphorus!!!! I try to always use the ULSD now that it is widely available and I have had good results so far.

jackhartjr · Jul 17, 2009

To Cat38Skip...when you are hooked to your 6-gallon jerry can and running....where is the fuel from the retun line to the tank going? If you don't understand that question...please call me at 828-310-811 one.
Or read Brobins75's post about his little fuel overflow problem when he did that.
Jack

Roger Long · Jul 17, 2009

RichH said:
"Fuel polishing" will NOT remove the bio-mass, etc.; and, if the biomass, etc. isn't removed it will most certainly 'slough-off' from the tank walls later and during the worst sea state conditions possible.

I think it's worth mentioning again the difference between "Fuel polishing" and "TANK polishing". (I know that you know this but, for benifit of discussion) The two terms are often used interchangably and shady characters make money pumping fuel uselessly around through filters.

Scrubbing by hand and visual inspection as you describe has got to be the best and most positive method but it can be done in tanks without inspection ports. Mine sat full of fuel for six years and the fuel turned to solid jelly in the hoses. It has only the small opening in one corner for the Tempro tank gauge and very restricted access over it. The yard pumped it out and filled it partially with fresh fuel that was then recirculated and filtereedd while being sprayed back into the tank with a pressure nozzle and directed around as much as possible.

I then ran it without problems for two seasons before becoming interested in the subject after my first fouled filter incident which followed my first use of StarTron. I put in my fuel polishing system that winter. After a season of using that and StarTron, I stuck a mirror in the gauge access and could see the scratches in the metal walls left over from the tank fabrication.

I've run about 500 miles under power so far this season and filter gauge pressures haven't changed. I just pulled my Racor filter element for a peek and it looked clean enough to just stick right back in.

RichH · Jul 17, 2009

Roger Long said:
......... The yard pumped it out and filled it partially with fresh fuel that was then recirculated and filtereedd while being sprayed back into the tank with a pressure nozzle and directed around as much as possible.

I then ran it without problems for two seasons before becoming interested in the subject after my first fouled filter incident which followed my first use of StarTron. I put in my fuel polishing system that winter. After a season of using that and StarTron, I stuck a mirror in the gauge access and could see the scratches in the metal walls left over from the tank fabrication.

Pressure wand cleaning can be equally effective in dislodging the bio-mass. Using Startron, etc. can effectively dislodge any remaining adhering resins (bio-mass) but it can be overwhelmed (there is a limit of how much Startron, etc. you can add) in keeping the particles 'in suspension'. However, since you now report that the Racors are not becoming 'challenged' you probably have a 'near pristine' condition inside the tank.

I think that the most important item from your message is: "I stuck a mirror ...." as one really needs to periodically inspect the internals. The reason for periodic visual inspection is that when using biocides, sometimes the bacteria & fungals develop 'resistance' to the compounds and a visual inspection will obviate the need (or not) to change 'brands' and type of biocide. Once you get a tank cleaned out, its relatively easy to keep it that way for quite some time - by onboard recirculation polishing, and/or addition of a biocide. Periodic visual internal inspection takes all the guesswork out of the equation.

Fuel Tank Cleaning

Barrie Point Roberts

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