Hunter Legend 35.5 ... 1991 Fuel in Bilge

Jan 26, 2021
10
Hunter Legend 35.5 Legend Port Royal
After sailing twice now we have had some fuel in the Bilge of the boat. I have ran the engine and haven't seen a single leak, also tightened all the clamps on hoses at the tank. There is no fuel around the tank and I can't find where it is coming from anyone else had this issue?
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
I had a leak at my Racor filter. It leaked when I moved the hose a bit. You might try running the engine and wiggling some connections.
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
What kind of engine?

Check the fuel lines around the motor, especially the return lines. the hoses get old and begin to seep a little. Once the one of the lines starts to leak, all of them will soon. Look for wet spots on the motor beneath the fuel injectors. Lift pumps are also prone to failing and leaking.

In the meantime get some of the oil absorbent bilge pads and put them under the engine.
 
Jan 4, 2006
6,444
Hunter 310 West Vancouver, B.C.
Try taping paper towels around any and all suspect fittings and check for any staining after a long run. Diesel fuel is a bear to track its source.
 
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Likes: Joseph Bauman
Mar 29, 2017
576
Hunter 30t 9805 littlecreek
Yep I use what's called a puppy training pad they sell at grocery stores. I put under engine then at least I can tell what corner of engine leaks are coming from
 
Jan 26, 2021
10
Hunter Legend 35.5 Legend Port Royal
Try taping paper towels around any and all suspect fittings and check for any staining after a long run. Diesel fuel is a bear to track its source.
I will try this, I know it's not in my main engine area because it's a separate area from the rest of the haul incase there is ever a leak and it's clean. I have a feeling it's in a hose coming from the tank, because originally the furthest point in the aft is where I saw it originally. Good idea though
 
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Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
If the leak is not from the hoses and not from the engine, then the tank may be leaking.

Tanks leak for several reasons

Water gets under the tank and the tank corrodes.
A dissimilar metal comes in contact with the tank, the tank corrodes. This is likely an errant screw.
Water inside the tank allows anerobic bacteria to grow. These sulfur digesting bacteria form colonies and their waste products are acidic. The acid is trapped within the colony and corrodes the aluminum. Interesting phenomena, look up "Microbiologically Induced Corrosion."

If the tank is leaking, its time for a new tank.
 
Jan 26, 2021
10
Hunter Legend 35.5 Legend Port Royal
What kind of engine?

Check the fuel lines around the motor, especially the return lines. the hoses get old and begin to seep a little. Once the one of the lines starts to leak, all of them will soon. Look for wet spots on the motor beneath the fuel injectors. Lift pumps are also prone to failing and leaking.

In the meantime get some of the oil absorbent bilge pads and put them under the engine.
It's a 27hp Yanmar. I will be doing a complete rundown this coming Saturday, I will reply if it has been solved at least I have a few things to try to narrow it down.
 

DougM

.
Jul 24, 2005
2,242
Beneteau 323 Manistee, MI
One of my friends had an elusive fuel system issue that ultimately caused the engine to shut down unexpectedly. He methodically went through the entire system and found nothing obvious. Then he picked up a section of fuel line he had laid on the galley countertop and found a puddle of fuel. The source was a nearly invisible age related crack in the line that was allowing the fuel to ooze out under pressure between the fuel pump and the injectors. Fuel line replaced, problem solved.
 
Jan 11, 2014
11,319
Sabre 362 113 Fair Haven, NY
One of my friends had an elusive fuel system issue that ultimately caused the engine to shut down unexpectedly. He methodically went through the entire system and found nothing obvious. Then he picked up a section of fuel line he had laid on the galley countertop and found a puddle of fuel. The source was a nearly invisible age related crack in the line that was allowing the fuel to ooze out under pressure between the fuel pump and the injectors. Fuel line replaced, problem solved.
This has been an issue with my Yanmar. The fuel lines have deteriorated and allowed diesel to slowly leak out, until it wasn't slow any more. The deterioration was most notable under the clamps where the fuel lines has become swollen.

On the JH series of Yanmar, there is rubber cap at one end of the return line that is particularly suspect. Once leaking the fuel can run along the line and drop somewhere distant from its source.