Fuel Tank Cleaning

RatherBFishn · 06-01-2003, 05:37 AM

I need my 97gal fuel tank cleaned. Does anyone know where I can get this done? I would really like to leave it in the boat if possible. I live in the Hillsboro/Aloha area.
Thanks Alot.

Lepper · 06-01-2003, 12:58 PM

all I have ever needed to do was flush and rinse.. flush and rinse.. the hard part is getting it to rinse !!!!

06-01-2003, 11:16 PM

Is there an access hatch that will give you access to the fuel level sending unit? You can take the sending unit mounting screws out and remove the unit. With a sponge attached SECURLY to a clean stick you should be able to clean the tank yourself. One tip.... If you value your eyebrows don't smoke when you are doing this :shocked:

RatherBFishn · 06-02-2003, 07:06 AM

Thanks for the advice. Unfortunately this tank has ribs or baffles in it that will not allow me to reach the ends of the tank or get even close to the pickup tube that is located at the back of the tank. Also the fuel gauge access hole is not very big (about 2.5" dia).

I took the boat out yesterday and it would run great, until at high rpm debris would clog the anti-siphon valve and it would stall. I cleaned the valve 3-4 times and each time the engine would run fine until the valve got clogged again. Varnish and some black gasketing compound were the culprits. I am thinking about removing the anti-siphon valve and replacing it with a straight-thru adaptor. I could run in this configuration temporarily and let the filters catch the debris. I also intend to add a good dose of carb/fuel cleaner to hopefully desolve the varnish crystals. (I ran about 15 gallons of cleaner enhanced fuel yesterday.) If anybody knows of a really good varnish disolver, let me know.

Once I get this problem solved, get some more accessories installed, buy some Tuna gear, then this boat will be heading for the great Tuna grounds. I will be needing some off-shore and Tuna catching experience and maybe will be asking for some experienced boat mates.

Sensei-san · 06-02-2003, 08:48 AM

Although it is dangerous to run without an anti-siphon valve, probably 99% of all older boats have had them removed.

Your plan of attack sounds good. The anti-varnish agent that works the best is plain ol' HEET. HEET is anhydrous isopropyl alcohol. You can get it in gallon containers at a chemical supply house. In the old days it used to be cheaper to buy it that way. But with all the DEA rules they might not sell it to you.

But the best defense is a good offense. Never buy fuel from a one pump station. Go to the highest volume station you can find. And never buy fuel if the tanker truck was just there.

Slugranch · 06-06-2003, 03:55 AM

Had a simular problem in a boat, that the guy used gasket sealer(the blue RTV) in,,,kept plugging my dip tube, and making fishing a general nuisance. Finally removed fuel gauge float assy. and manufactured a probe out of 3/8 copper tubing with a flexible hose to an inline fuel filter and then a 12 volt fuel pump, and then a return back to the tank. Used a flashlight and a lot of scrounging and recirculated all of the fuel I could and removed a lot of scale and of course the blue stuff. It was a lot like a slimy substance more than just a slug of rubber. The unleaded gasoline is really clear, unlike the old leaded gas that was dyed red, so seeing the bottom of the tank was no problem. After a lot of recirculating, went to a local paint store and purchased a wire mesh filter that slid over the end of the fuel dip tube. They are designed to go on the dip tube of an airless spray outfit. They are made of stainless mesh, and are just the right size to fit the dip tube. I considered fastening the screen to the tube, but was concerned about the clearance to get it back in the tank, so very gingerly slid it back in and because the dip tube was only like 1 1/2" from the bottom of the tank, it couldn't slide off. Lasted me for the remaining three years that I owned the boat, and I never had another problem with the fuel system.

Pilar · 06-06-2003, 07:45 AM

Slugranch, you are describing a crude form of fuel 'polishing'. The fuel is recirculated and filtered to remove the crud. I do not have one to refer you to but there are places that do this in the boat.

RatherbFishin, the 'black' stuff may be rubber sand from decomposing fuel lines. The black rubber fuel lines that are so common get hardened by ethanol fuels and crumble from the inside out forming a black sand that continues to shed and never goes away. The only way to fix it is replace the hoses. Check to see if your hoses are deteriorating from age.

RatherBFishn · 06-06-2003, 09:26 AM

Thanks for the info guys. My biggest problem with this tank are the ribs inside the tank. I can't get anything down into the corners or back of the tank were most of the "stuff" settles too. I have thought of recirculating the gas through a filter but just haven't come up with an economical, easy and safe way to do this yet using non-spark pumps. I think I will just remove the anti-siphon valve, run the tank dry a few times and let the 2 spin-on filters catch the "stuff". Or maybe I will buy an electric fuel pump and install it in the boat for emergency added pumping power??? I could use this electic fuel pump to recirculate/filter the gas as well. The stuff is varnish and black gasketing RTV. I have removed and inspected the fuel hoses. They seem to be in pretty good shape and I haven't seen any indication of rubber fuel line debris. Once I am very confident that the fuel line will no longer get restricted then I won't have to carry the small portable gas tanks with me anymore. What a pain this has been but at least I now know the source of my problems and should be able to deal with it after I get back from Hawaii. VERY anxious to go off-shore fishing this summer.

Pilar · 06-06-2003, 09:58 AM

RatherBfishin ... You can get an electric fuel pump that is Marine SAE rated from Holley but it is very expensive. ~$150.

A cheaper alternative that is not SAE Marine rated and will not pass CG inspection is the electric fuel pumps you can get at Schucks or Thrifty. Prestolite makes 2 for after market auto application. They are boxy looking and have 2 different flow rates and pressure ratings that should match your motor.

I use this pump on my boat and the checkvalves in the pump substitute for the antisiphon checkvalve you normally find on the tank. It has been my experience that the antisiphon valve has a very stiff spring and some pumps can barely pull fuel through it. Then a guy adds fuel separators and filters also on the suction side of the engine mechanical pump and it really struggles at low speeds.

So the fix on my boat is to place this electric prestolite pump right at the tank. The line from the tank goes to the pump and the antisiphon valve is replaced with a plain hose barb. Then from the electric pump to a fuel/water separator, then to the mechanical pump (this also has a cartridge filter in it) and then to the carb.

If I have problems with the fuel/water separator getting plugged or the lines lose their prime, I run the electric for a minute or two and ram all the bubbles through the system to get the fuel going again. If the fuel pump on the engine quits working I can run home with the electric running instead. It will push the fuel right through. Priming the pump with your engine starter usually runs your battery down. The electric pump works pretty good.

Like I said above the cheap Prestolite electric pump is not Marine kosher and the guy at the auto parts store will not sell you one if you say the word 'Boat'. So if you do this it is at your own risk.