Deisel tank help

[Nazrat1971]

Hi there. Proud new owner of a 1971 Challenger 32' here. It has been on the dry for the last 6 years .We have gone through the yanmar and are ready to fire her up. We just put about a gallon in and our main fuel hose filled up?We checked the vent hose and it was full of fuel as well. any port on the tank we tried to burp was pushing out fuel as well. The only thing I can think of is the tank is already full of fuel.we were told it was drained at the time of drydocking and when knocked it sounds very empty. I really don't understand what is happening and hope it is somthing stupid we are missing.

Any help or ideas would be appreciated. Thanks all!

[AndyEss]

Is there an access or dipstick port you can open? Have absorbent pads handy because it sounds like you have tried filling an already filled tank.

[Nazrat1971]

Originally Posted by AndyEss

Is there an access or dipstick port you can open? Have absorbent pads handy because it sounds like you have tried filling an already filled tank.

Any port we open on the tank spills fuel instantly. When tapped, the tank sounds absolutely empty/hollow.But It only makes sense that the tank is full And the added fuel is going to the vent and fill hose.

Is there perhaps some sort of flap valve that is Stuck closed or a segregated section of the tank that is not allowing fuel to the main holding tank?

[AndyEss]

If you get fuel spillage from any open port, it sure sounds (despite the tapping test) like the tank is fill.
I've never seen a check valve on a diesel fuel fill, but it would be set up to fill the tank (and prevent reverse flow) rather than preventing fuel from entering the tank.
Maybe you have a double wall tank (or you are tapping on something else) and that's why it sounds empty. Maybe the tank has different wall thicknesses than what you are used to, and it sounds different in your tap test.
Fire up the engine, and run it for more than 1 gallon of use - if the engine runs out of fuel, your tap was right.

[mike d.]

Maybe the tank is full of water ! Diesel is lighter than water !!

[Nazrat1971]

Thanks Andy. I did not think of a double wall. The fun part about this is the boat has been on the dry for 6 years So now we get to pump out ~30 gallons of diesel so we can get some fresh stuff in there.

[billknny]

Originally Posted by Nazrat1971

Thanks Andy. I did not think of a double wall. The fun part about this is the boat has been on the dry for 6 years So now we get to pump out ~30 gallons of diesel so we can get some fresh stuff in there.

Nazrat,

Good thinking! Starting and running your engine using 6 year old fuel of uncertain cleanliness and provenance is truly a recipe for disaster!