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Fuel in Bilge

thostorey

Regular Contributor
"Here’s the setup. Engine is a

"Here’s the setup. Engine is an AQ 151C with a Weber carb. Boat is a 185 Malibu. The re-fuel point is high on the transom and runs via standard fuel hose to the tank forward of the engine. Fuel vent is from the tank to the transom. When adding fuel a hiss is heard at the vent and it will spit fuel overboard when the tank is near full.

Fuel delivery is: from the tank to the fuel/water separator to the filter, two outlet ports, one to the fuel pump and one to the auxiliary fuel line for the kicker. A fuel shut-off is located before the fuel/water separator. The auxiliary hose to the kicker has a shut off but it is usually open and the kicker connection hangs over the back of the transom and is secured. The fuel pump fault hose is secure and not blocked.

Over the past year on about 4 occasions I have come to the boat to find that about 3 or 4 cups of fuel in the bilge and I have no idea where it is coming from. It is always about the same quantity of fuel. The spill has happened when the tank was ½ full and fuller, when the boat was covered and in the hot sun and when it was not so hot in the boat. It has happened when the main fuel shut-off at the fuel/water separator was either open or closed, boat in the water or on the trailer. It never has leaked when I was around to see it.

I have wiped the length of the filler hose, vent line, fuel pump feed line, carb feed line, looking for a tell-tale stain form the marked gas and found none. I will soon uncover the fuel tanks and look in that area for signs of leakage.

I’d like suggestions/guesses as to where to look?? both on and around the engine and in the fuel tank bay. I’m at a bit of a loss….However, due to the large quantity of fuel I think it must be coming from a large container, like the filter of the fuel/water separator; either that or from a main tank. There is just not that much fuel above above the fuel pump?

Thanks, Tom"
 
"Tom, I had to replace the fue

"Tom, I had to replace the fuel tanks (under deck) in my last two boats, as they were aluminum and they got perforated due to corrosion (and old age). Many times, the fuel tank compartment has a tell tale that drains into the bilge (though I don't think it is necessarily a good idea).

Could that be your case?"
 
"Yes, if the tanks were holed

"Yes, if the tanks were holed the fuel would easily drain back into the bilge as there is a channel connector between the two compartments. But I would think that if there were a tank leak it would be constant, not intermittent. I'll go for weeks without a leak and then - at least a litre will show up. I was out today in rough water and not a sausage of fuel in the bilge so it does not seem to being thrown out an upper surface exit. It appears to be more of an over pressurization exit??? Very frustrating... Guess I'd better start with changing the fuel/water separator and go from there...."
 
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