Gas Tank Question

[Scotta1973]

Long Story,

After seeing JimCT's post of stringers pulled from the deck I decided to expand my transom rebuild project to look into whether my stringers had pulled away.

What I found was the foam in the port stringer, towards the stern, is not waterlogged but rather the bottom two inches is gasoline-logged. I had visions of Miami Vice exploding boat scenes.

So next I removed the gas tank to find a small hole in the stringer in the area where the gas tank sits  which could have been the area that initially received the gasoline. Maybe the breach occurred on the replacement of the tank, the "new" tank is a 1990's plastic tank.

In any case I think the gas entered the situation through faulty connections in the various tubes that attach to the gas tank. My question is this how do I determine if the tank itself has a leak, I am assuming through some sort of air presure test but I am not sure how to go about it, I do not own a heavy duty air compressor and don't want to buy one, could I take this to a local mechanic?

Any thoughts would be much appreciated.

Scott

[JimCt]

Pull the tank out of the boat and remove any remaining fuel from the tank.  Set the tank up on sawhorses and fill it with water, preferably outside where the sun can hit it for most of the day.  With the ouside of the tank perfectly bone dry, dust the whole surface with very fine powder... baby powder, confectioner's sugar or what have you.  If you see immediate signs in the powder of leaking water you've found the problem.  If you don't see any leaking immediately, let the tank sit outside for a day or so.  The temperature excursion from day, with direct sunlight, to night and lower temperatures will reveal a slow leak if it's there.

This is the method I used and it worked for me to find a very slow leak.  I had found gas in my Starboard stringer.

If you do find a leak, don't screw with it; replace the tank.  Go with aluminum for the replacement.  It's worth the money in peace of mind.

[John Jones]

NEVER put a lot of air pressure on any kind of tank!!!!!

Two PSI is enough to leak test a tank.  30 PSI can rupture a fuel tank.  Don't screw around with gasoline, especially in an enclosed area.  Get a new tank and be done with it.