How to remove fuel "varnish" from built in tanks?

[Caddy_Kid]

I have a 16' Stevens outboard boat with two built in fuel tanks on either side of the seats. They havent been used for years as the previous owner swore that they were filled with mud. He instead used a carry on tank.<br /><br />When I got it home, the "mud" that he was talking about was really old, putrid gas in the port tank and a heavy fuel "varnish" but no fuel in the starboard tank.<br /><br />They are factory fiberglass tanks that were glassed to the bottom, so there is no way at all to remove them. It has been hard enough to get new fuel lines on them.<br /><br />Anyway, I removed the old gas from the port tank and am fairly pleased with its condition. However, the starboard tank is what worries me. How can I go about getting the varnish out? I imagine that new gas will disolve it eventually, in which case could I just use an inline fuel filter and change it often till its gone? Or is there a way to disolve it with chemicals in the garage? Thanks.

 

[deeep water]

Re: How to remove fuel "varnish" from built in tanks?

can you get a sample of the gunk out of the tank ?? if you can,,you can test several solvents to see wat works the fastest ,,and check with maker to be sure it wont desolve your tanks ,,and inline filters are always a good idea ,,if the boat is on a trailer ,,balance it out so you can rock it foward and back like a teter totter,,warming it up a bit will help,,no real heat ,,look for a glass sedament type filter,or make one good luck

 

[Richard Petersen]

Re: How to remove fuel "varnish" from built in tanks?

This is going to cost around $60. Find a marina or gasoline dealer that has a gasoline fuel tank pump. You want to have a can of SEAFOAM engine cleaner on hand. Guess the size of your gummy tank. Know how much cleaner the tank should need for 1/4 full. Get the pump hooked up to only recirculate the gas and SEAFOAM for about 45 minutes. Then have other tanks to EMPTY the bad gas out of your tank. After that then put in a GOOD sized filter unit. It will probably clog a few times. Always use the SEAFOAM for at least 2 full tanks of gas. To keep the gum flowing out the engine exhaust. Same for the other tank. Has always worked for me. Ckeck with SEAFOAM to be sure it is OK to do the treatment as I stated. I am a geezer.

 

[crazy charlie]

Re: How to remove fuel "varnish" from built in tanks?

Depending on how much goop is in the tank ,you should get some kerosene to dilute and dissolve it and siphon or pump it out when dissolved.Charlie

 

[HollaGeo]

Re: How to remove fuel "varnish" from built in tanks?

Power-Wash the tank.

 

[Caddy_Kid]

Re: How to remove fuel "varnish" from built in tanks?

Been putting up christmas lights all day, so I havent had a chance to take another look at it. With any luck I will get something done on it tomorrow, as we are done decorating. Well, my part at least. Thanks.

 

[Josh9685]

Re: How to remove fuel "varnish" from built in tanks?

I don't think putting gasoline or kerosene will dissove the varnish.<br /><br />I had a similar situation with about a gallon of varnish in the tank. I filled it with gas(20 gal.)<br />the boat ran fine but would occasionally bog down and run poorly. the fuel filter is for removing sediment and is permeable to liquids. eventually the varnish gummed up my carbeurator and now I have to rebuild it. <br />it may be a bad idea to fill the tank up with solvents becuase it may eat through the tank and/or eat fuel lines, pumps, carb. parts. etc etc.<br />best bet is to remove as much of the varnish as possible. I think but am not certain that varnish floats on gas. that appeared to be the case when I drained mine. when it is all drained put some more gas in it and siphon it again. repeat a few times. run it in your lawnmower or whatever, these are more tolerant to dirty fuel, and much easier to clean carb. out.

 

[Buttanic]

Re: How to remove fuel "varnish" from built in tanks?

Laquer thinner will disolve it.

 

[Caddy_Kid]

Re: How to remove fuel "varnish" from built in tanks?

My tank doesent seem to have any large amount of solidified varnish, just all over the sides and bottom in a thin layer. I have a fuel filter and a water/fuel seperator, so I will probably use both then. Thanks.