leaking fuel tank

[amidaeus]

I think I know the answer to this one, but I don't like it... I just finished repairing my deck and laying 3 layers of fiberglass then sprayed Ultratuff on it. Today I started installing everything I had gutted from the boat and noticed a gas smell. Opened up the front storage hatch and had about a quart of gasoline in the hull. My boat is a 1980 21' chriscraft scorpion with about a 40 gallon aluminun gas tank. The boat has been sitting for a year on my inclined driveway with the bow at the low end. I thought that it may be leaking through the vent or fill necks but it is dry. I can't get to the tank,I can only see the vent/fill necks, the sending unit and the petcock. Is there anything I can do without ripping up my brand new deck to fix/replace the leaking fuel tank? The only thing I can think of was to drain the tank and buy a couple of portable tanks and run off of those, but I really am hoping there is another way to fix the tank or if I missed something else that could be leaking besides the tank itself.

 

[18rabbit]

Re: leaking fuel tank

Before you start ripping apart your boat to replace the fuel tank, test it to see if it is really the source of the fuel in your boat. Basically, you remove the fuel from the tank, place temp caps on the vent and fuel lines, then apply a couple pounds of air pressure to the fill line and see if it holds.<br /><br />Another member here had a similar problem last year. Search the iboats forums for postings from KESH. There is a tread on how he made a manometer for testing his tank.

 

[Luna Sea]

Re: leaking fuel tank

I too need to test one of my tanks, if you find the post, please paste it in this one. <br /><br />Was your tank full? Could just be expansion in the bilge. Or a leaky hose maybe?<br /><br />Only good news is the glass job will go faster the second time if you have to pull the deck up again.....

 

[KaGee]

Re: leaking fuel tank

Any chance you accidently ran a screw or drill bit into it?<br /><br />An aluminum tank shouldn't just leak like that, but it could happen. <br /><br />I'm with Cap'n Mike... look at your connections. That's the most obvious starting place.

 

[18rabbit]

Re: leaking fuel tank

Here’s the link for Kesh’s fuel tank rehabilitation efforts. I checked a couple of the links and they are still valid ... see pics of manometers. (Note: I incorrectly called it a hydrometer in my post above. Don't look, I fixed it. )<br /><br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=008032#000000

 

[DJ]

Re: leaking fuel tank

I hate to bring bad news but if that tank is original (1980) it would not be that unusual for it to have sprung a leak.<br /><br />You have to test it true, however, I would not, at this point, discount opening up an inspection hatch to see.<br /><br />If you plan it right, you should be able to just lift off enough of the floor to get to the culprit. Resealing it, while not fun, should not be too big of a deal.<br /><br />Whatever you do, don't reinstall that tank, even if you think it's fixed. They never are. <br /><br />The likeliness of the tank leaking is directly proportional to the difficulty of removing it.

 

[amidaeus]

Re: leaking fuel tank

Thanks for all the advice. I could not siphon the tank so I plugged vent and attached a hose to the petcock outlet and applied pressure through the fill neck. After getting 45 gallons of gas out of it I have filled my daughter's car, my wifes car and my mother in law's is nearly topped off. With the price of gas nowdays I sure wasn't gonna waste it. I am gonna try the pressure test, but I really think there is a pinhole leak some where. The way this boat is designed I can't possibly pull the tank without tearing up the new floor. I take my family out in this boat and want to be sure it does not turn into an inferno on the water. Im gonna buy 2 twelve gallon platic tanks and put them under the rear seats with a valve. I just can't risk it. I appreciate everyones input and was hoping for some miraculous way to fix it, but i guess I will buck up and spend the cash...

 

[Luna Sea]

Re: leaking fuel tank

I had to cut some gas tanks up with a sawzall a few years back. Couldn't get them out of the 46 foot Chris Craft without ripping up the decks. An "old timer", who was advising me on the project, told me putting bleach in there before starting up the saw would kill the fumes. So, you may want to dump some bleach in there to kill the fumes as an empty tank can sometimes be more of a hazzard.....

 

[18rabbit]

Re: leaking fuel tank

Excellent point, Luna Sea. Any fumes in there would be highly flammable…no different from the fumes that collect in a bilge, except they are confined and probably more concentrated.

 

[Chris1956]

Re: leaking fuel tank

If the leaking is not too bad there is an epoxy-based product that you pour into the gas tank and is coats the interior of the tank and hardens to plug minor leaks. I did not see it in a marine catalog I just looked at, so you may want to try an automotive parts place, since they use it for auto gas tanks.

 

[amidaeus]

Re: leaking fuel tank

Chris, I did find some stuff like that on the internet, but it says you have to remove the tank to use it. That is what I was trying to avoid.

 

[Weedy]

Re: leaking fuel tank

Amidaeus, I have replaced many of fuel tanks on boats ( I used to run a service dept. of a well known flats boat manufacter), when you have one small pin hole, that normally means there are alot more. Do Not take the chance to fix one small hole, like said above, DO NOT TRY AND REPAIR and REINSTALL! It is not worth the effort to fix a tank unless it is fairly new, also, it is not cost affective. I have never liked to tell someone this, but the money to replace it now, is well worth it down the road with peace of mind. Your family is worth more than a few hundred dollars for a new tank and the hasel to redo the floor! Good luck with your venture.<br />Weedy

 

[drjohn]

Re: leaking fuel tank

Amidaeus, I understand where you are coming from. I have a 1990 Wellcraft Sportbride and in April of 2002 I, too, notice a fuel smell. I touched the bottom of the port tank and it was wet with gas. I had a local guy come out and siphon the gas from the port tank and put it back into the starboard. I called Wellcraft and they said that to get the tanks out I had to pull the engines. I did a lot of research on the subject and found, not only was it futile to think about repairing the tank, but I probably needed to replace both. Once they were pulled, I could see the tremendous amount of rot under both tanks. All of that old wooden supporting structure was replaced with starboard and I had both new tanks painted with epoxy to prevent future problems. I agree with WEEDY, if you've got one leak, you can count on more later. Good luck.

 

[Mark42]

Re: leaking fuel tank

If you are going to cut tank and afraid of sparks with the vapors, put a few pounds of crushed dry ice in there. The CO2 is heavy and will displace the air and will not support combustion.