Fuel leak at 100 miles

During my first offshore trip this summer (8/10-8/12), I had planned to fish the bluefin at the 120 mile mark. I topped off the tank and trailered the boat down to MCRD for launch. Left around 10:00PM and motored south all night. At sun rise we were only 80 miles south, so I ran for a little over an hour. The radio reports were now coming in and guys ar reporting catching the 50lb models. With twenty miles to go I decided to lift the engine cover and just do a quick safety look. There was a couple gallons of fuel in the bilge! After pulling the side covers to assess the hoses and the sides of the tank nothing was apparent as being the source of fuel leakage. There was no fuel leaking from the fuel pump, injectors, or other area on the engine. I know my tank is 27 yrs old so, I'm thinking a hole somewhere in the tank. I soaked up all the fuel in the bilge and watched to see if more was coming into the bilge. As I watched fuel slowly trickle from the hole that seperates the two bilge areas (one under the tank), I get a crappy feeling. Meanwhile the radio reports are sounding real good. My buddy was pumped to hook into a big BF. Unfortunately, I made the call to turn north. My vessel assist is only good to 100 miles. As we continued north, fuel was still accumulating in the bilge but, at a much slower rate (about a pint an hour). Decided to continue north and fish paddies on the way home and if the fuel stopped flowing then anchor at the Coronados and fish locally the next day. The fuel did stop altogether. At home I pulled the bait tank and deck cover to assess the fuel tank and get a better look at the hoses. The main fill hose had a 2 inch crack in it and there were no signs of other leaks. To gain a little more confidence in my tank I decided to do a pressure test. Mike lent me a small compressor with the guages. Someone told me to place the tank under 12 lbs of pressure but, Mike said that was not a good idea as the tank is already old and it's aluminum. Mike recommended 1lb. I hooked the compressor up to the fuel vent hose and placed a balloon over the main fill outlet just to get a visual idea of how much pressure 1lb was. As usual, Mike was right. One 1lb was plenty. After finding a small air leak on the top of the sender and fixing it, the tank held 1lb of pressure for about 15 minutes. That was good enough for me. Slapped everything back together (with new fill hose), added 5200 to all gaps in the deck and around the bait tank and it's back in business for Tenacious. Past couple trips revealed no fuel leakage. So gentlemen, check those old hoses!

Good thing it's diesel. Glad you made it back safely and good advice!

Its amazing I am having a very similar situation.

About a month ago I filled the boat with fuel and during the fishing trip I noticed fuel in the fish hold. I figured something must be leaking around the tank as well. Opened up the floor and found a bad hose not sure if main or return fuel but I am planning on replacing both plus inspecting the main fill as well. Not sure why fuel would have leaked just because I filled the tank, maybe main fill is leaking believe me I will inspect.

With the age of the boat I don't mind doing these types of repairs this way I know everything is sound.

In the pic you will notice I cut the floor out, the floor was redone and it was fiberglassed over the access to the tank. I plan on replacing the cover with starboard and a nice molding for easy access in the future if the tank does go bad. Plus clean up the rat shit! The boat was stored for quite some time.
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Glad you cought it and made it home safe. Good advice.

Your tank looks about like mine minus the rat shit. My main fuel hose was the source and because the hose came off the top of the fuel tank and actually dipped about an inch below the top of the tank before snaking up to the fill cap. The cracked part was just above the fuel tank but, I guess it was close enough that when I bounced, fuel splashed up into the hose and then into the area below the tank. You might try the pressure test if you are concerned about any holes in the underside or sides of the tank. It just give you a piece of mind. I like the starboard idea. I just used marine plywood then glassed the wood (didn't glass over the deck though). I just screwed that plywood down then filled in spaces with 5200. It was still difficult to remove the piece with that 5200. Might try a sealant that's not as tough?

If you've gotten 27 years out of the tank, you've done well!

I just went through the same process in the 23 outer banks I just sold. If you want any tips on removing, replacing etc.. Let me know, glad to share my insight. Do your self the favor and remove all that foam!!!!! Some will dis agree, others will not. When you replace it it is better to have air space around the entire tank, just in case any moisture gets down there. Foam does not allow anything to ever dry out. I know your not suppose to get moisture around that space but it always does. JUST SAYIN!!!!
O yea buy a limb saw at the home depot. It will help

Josh
310-869-6573