Fuel Leak

[OdayGeorge]

OK, I am completely stumped. I can't find a fuel leak. I hadn't used my boat in about five days. As customary, I check the bilge before I go out (wish I checked it on the way in) and found liquid with a familiar smell. I taste the "water" to see if it's salt or fresh and was surprised to find it was diesel fuel. I manually collected about 2 gallons!

After cleaning the bilge, I looked around the engine. The engine oil pan was dry. So after opening the access point in the starboard birth, there was a small amount of fuel between the engine and the fuel tank. I didn't see any oil trails or wet hoses which might help me find he source. After cleaning the area, I turned on the fuel pump for 10 minutes and no leaks. I ran the engine for 5 minutes and no leaks. I checked the fuel level, about 5/8's of a tank. The fill and vent hoses are tight and leak trails are not evident. The seams on the tank all look good.

I let the boat sit overnight, and no fuel leaks anywhere so the bottom of the fuel tank is OK. I don't have a spare jug of fuel on-board. Any thoughts? Gremlins? Tuesday morning, we'll take it out and make a number of tight turns and see if anything turns up.

 

[Michael Davis]

I've had injector pumps leak and return lines leak but they left a trail. I hate problems that just go away without being fixed. You never know when they'll return.

 

[SG]

My "guesses" (which you have sort of debunked) are

• Fuel fill hose;
• Return fuel line;
• Leak at discharge side of (Racor) prefilter.

In your case, I'd look at a leak in the tank "bottom" or seams. Can you get an absorbent pad or paper towels to "trace" the leak at positions around the tank. It's possible that you might need to fill the tank up (or heal the boat over, if you were in weather where that was an issue before you brought the boat in and the "leak appeared".)

 

[SailingCal21]

Not sure about the layout of O31's but my 1981 O34 had pinholes in the lower section of the tank due to crevice corrosion of the aluminum due to lack of oxygen in a wet environment. You may want to check to see if there are any chronic leaks onto the top of the fuel tank that are collecting between the tank and it's mounting structure.

Don't mean to be a negative-Nelly, but the fuel came from somewhere.

 

[Tom J]

In your case, I'd look at a leak in the tank "bottom" or seams. Can you get an absorbent pad or paper towels to "trace" the leak at positions around the tank. It's possible that you might need to fill the tank up (or heal the boat over, if you were in weather where that was an issue before you brought the boat in and the "leak appeared".)

My boat was almost new when I smelled diesel and found a puddle in the shallow pan under the fuel tank. It only leaked when I healed while sailing. I had the tank pulled and there was a tiny pin hole in the weld on one of the seams. I had that welded and all was good.