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How to remove gummy buildup from old gas tank?

ImageDiscuss boat maintenance and repair issues here.

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Your Vessel Info: 43' Lazy Days houseboat
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How to remove gummy buildup from old gas tank?

Unread postby nopeda » Wed May 22, 2019 2:58 am

I have a 1968 Lazy Days Sportsman. 43 ft. long 12 ft. wide aluminum hull houseboat. One of the gas tanks hasn't been used in a long time, possibly 10 years or more. I'm pumping out the old gas which is very dark reddish in color with an electric fuel pump that seems to be having a hard time and is going very slowly...sometimes not pumping at all. I have the end of the intake gas line tie wrapped to a copper rod which holds it about 1/2" above the bottom of the tank, going in from the fill cap which is conveniently directly above the tank. With the copper rod I can feel a bunch of gummy build up on the bottom of the tank and when I pull the rod out there is a wad of what looks like tar stuck to it. The tank very unfortunately feels like it is welded in place or I would try taking it to a radiator place or something or maybe replace it entirely, but as I mentioned if feels welded in place. It looks like it's made of galvanized steel and a magnet sticks to it very well so it's not aluminum or stainless, right? Is there some fluid I can pour in the tank that will break down the tarry buildup so I can suck it out with the electric fuel pump? Something that will clean out the tank without hurting it and also clean the fuel pump without hurting it either?

Thank you for any suggestions!


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Re: How to remove gummy buildup from old gas tank?

Unread postby CaptForce » Wed May 22, 2019 7:58 am

I would guess that the best solvent to dissolve the "tar" would be the same gasoline from which it was derived. I would take a sample of the material gathered from the rod that you pulled out of the tank and place it in a glass container. Stir in some fresh gasoline to see if it dissolves; if not, try kerosene. Your solution will definitely be an apolar solvent and not water. Be careful to maintain good ventilation and stay safe from any ignition source.
'good luck.
Take care and joy, Aythya crew

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