Fueltank twilight zone

gohelm · 07 December 2011, 20:24

After having the boat in storage( fully horizontal) for 3 weeks we seem to have fuel 'appearing' on the floor of the boat without an obvious cause/reason. All connections etcetera remain dry however there is a small amount of fuels lying below the fuel venting plug.
Other weird bit is the if your remove the filler cap there is a hissing sound like the venting plug isnt working, it is working fine however!

Does anybody ever removed a tank out of a delta? And can it be ( my best guess so far)that the vent is attached to a pipe which leads to the bottom of the tank instead of to the top? (because that would create the ultimate non return valve: air can go in but cannot get out anymore)

Any assistance understanding this ( and solving it) would be great!

Gabor

biffer · 08 December 2011, 10:51

Delta have a funny way of doing the fuel systems sometimes. If there was fuel in the vent pipe that would account for it.
Pressure your tank with your tube foot pump to see if fuel comes out of the vent. I will assume that a company like delta would have done the vent right. It should be just in the top of the tank not to the bottom

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9D280 · 09 December 2011, 08:25

Could it be condensed evaporated fuel?

If the temp is cycling, the vent could be allowing the small amount of vapour that is generated in the "warm" condition to be the first to condense when the temp drops at night. Fuel then re- liquidises on the vent wall and assuming you have ai ninverted "U" i nthe pipe to stop water ingress it doesn't get sooked back in and drips out the open end.

Leave stationary for a while and he presto, puddle of fuel created by a drop or two per day. When in use any of that would be dispersed by bige water , movement etc. and probably not even condense in the first place as I guess it would be summer.

willk · 09 December 2011, 08:49

Have you disconnected any of the fuel lines/breather pipes recently? I've heard some interesting stories of incorrectly refitted hoses.... A swapped return and vent might do the trick.

You mention a hiss when opening the fuel tank and you also say the vent is working. Only one of these things can be correct as there could be no pressure if the vent was working correctly.

Is the tank very full with fuel? An "overfilled" tank might have covered the vent pipe with fuel. As the pressure built up, fuel would be forced up the vent until a little was spilled, reducing the pressure again.

gohelm · 09 December 2011, 09:38

Quote:

Originally Posted by willk

Have you disconnected any of the fuel lines/breather pipes recently? I've heard some interesting stories of incorrectly refitted hoses.... A swapped return and vent might do the trick.

I only changed the nozzle (on top of the jockeyseat - the fillercap is also situated here(under the seat) )

Quote:

Originally Posted by willk

You mention a hiss when opening the fuel tank and you also say the vent is working. Only one of these things can be correct as there could be no pressure if the vent was working correctly.

i meant by working correctly : it is letting air in and air out when filling up so it is only after this storage the 'hiss' is apparent.

Quote:

Originally Posted by willk

Is the tank very full with fuel? An "overfilled" tank might have covered the vent pipe with fuel. As the pressure built up, fuel would be forced up the vent until a little was spilled, reducing the pressure again.

boat was not stored with a full tank, that would indeed be the most obvious reason....but it seems to be 'burping fuel' with less

gohelm · 09 December 2011, 09:44

Quote:

Originally Posted by 9D280

Could it be condensed evaporated fuel?

If the temp is cycling, the vent could be allowing the small amount of vapour that is generated in the "warm" condition to be the first to condense when the temp drops at night. Fuel then re- liquidises on the vent wall and assuming you have ai ninverted "U" i nthe pipe to stop water ingress it doesn't get sooked back in and drips out the open end.

Leave stationary for a while and he presto, puddle of fuel created by a drop or two per day. When in use any of that would be dispersed by bige water , movement etc. and probably not even condense in the first place as I guess it would be summer.

hmmmm - yeah, that is definately a possibility, thanks!

One thing i forgot to mention.. the fuel apparent seems to be a funky blue-ish colour. I considered the smurfs had been borrowing fuel and then refilled the tank during one night but the owner of the storage place is having cats (so storage should be smurf free) . could there be any other reason for this discolouration? (checked the flanges used and all seem to be fine)

SPR · 09 December 2011, 10:21

talking of smurfs - what colour does a Smurf go when you choke it?

S.

gohelm · 09 December 2011, 11:15

Quote:

Originally Posted by SPR

talking of smurfs - what colour does a Smurf go when you choke it?

S.

no idea but with all the rubber glued to the sides of the boat nowadays it will at least be 'safe' ;-)

gohelm · 09 December 2011, 11:29

Quote:

Originally Posted by SPR

talking of smurfs - what colour does a Smurf go when you choke it?

S.

I tried to avoid the Smurf jokes after the blue fuel - clearly unsuccesfull...;-)

Thanks suggestions so far- I will try the pump trick Biffer suggested and see what happens. Avoiding condensation implies storing the boat with a full tank.. will try that as well if 'plan A' doesnt shed some light on this. Thank you guys!

Hightower · 09 December 2011, 12:33

I found with my old RIB that sometimes if I topped up the tank a little fuel would come out of the vent pipe and on to the deck. This in it's self wasn't a major problem for me as I learnt to guess when I was near the top and slow the pump to prevent this.

However, the vent pipe inside the console went though a full 360 deg before terminating in to the top of the tank. Fuel would sit in the U bend and act like a plug of water in a U bend on a drain. Perhaps the expansion of air inside the tank is pushing this plug of fuel up the pipe and out of the vent.

Easy to fix if that's your problem. Remove the U shape by routing the tube direct from the vent to tank.

Delta Rich · 09 December 2011, 14:54

Quote:

Originally Posted by biffer

Delta have a funny way of doing the fuel systems sometimes.

How so?

biffer · 09 December 2011, 15:12

Quote:

Originally Posted by Delta Rich

How so?

Fuel manifolds with flows and returns in them. One gallon expansion tanks on the side. I don't see why they needed all that on the one I changed. Took it all out put a return back to the tanks. New filters and away she went. Been going well ever since. The manifold was a work of art though

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