Fuel tank blues...QUESTION

[coolchange]

Our marina keeps the price on diesel at $5 and that has me the proud owner of a 5 gal can (pay myself 10 bucks to walk it down and pour)...at least that was my thought until the first gallon started coming out the overflow...and I know the tank is at least 2/3 empty (room for 20-30 gallons).

I can poke a 3ft. stick down the fill spout..which should get it to about 1/2 way to the bottom of the tank..but for sure past the fill tube and the fuel comes out the overflow in a clean full stream (no bug nests here)

So...my thought is there may be some sort of "flap" at the top of the tank which is to keep surge from splashing up the overflow and fill tube...and that this flap has enough of a spring that it can hold the column of fuel (coming in very slowly from the hand pour) thus allowing the pour to start out the overflow even though the tank wants/needs the fuel.

Am I on a "right track" or do you have a better idea??

[Jay Knoll]

Cool

I"ve never heard of such a setup in a fuel tank. Do you have a single or double tanks on your boat. My FC has two tanks, with a hose/valve setup that allows me to "manage" the flow of fuel to/from the engine. I can draw from on tank, return to the other, draw/return from one tank completely isolating the other, etc. I don't bother, I just draw from both tanks and return to both, watching the overall level on the dash board fuel gauge.

What I'm leading up to is, if you have a similar fuel management system, could you inadvertently be drawing from one tank, which is really low, but you're trying to fill the other tank which is, already, FULL? Just a thought.

I would get a longer stick and sound both tanks to determine their respective levels.

Good luck

Jay

[denchen]

Is the bottom of the overflow (vent) pipe somehow now gone lower in the tank??????

[tego]

Coolchange, I'm assuming your boat has two 50 gal tanks. Does your fuel gauge show one tank 2/3 empty and the other full? Do you have the standard array of valves on the aft bulkhead of the engine compartment for fuel management? Make sure all the valves are "open". Then make sure someone didn't switch the spade connectors on the fuel tank gauge switch, giving you an erroneous reading on which tank is full and which is 2/3 empty. Actually, this is a fairly common occurrence. There is no flapper valve in the fuel fill line, which leads me to believe that the tank you are trying to fill is already full. You can check the electrical connection accuracy by disconnecting the lead on one of your tanks and verifying that that tank is the same one indicated on the switch panel at the helm. good luck, Ben

[Beta Don]

...and I know the tank is at least 2/3 empty (room for 20-30 gallons).

How do you 'know' what you think you know?

When fuel runs out of the vent, you can usually be pretty sure the tank is actually . . . . full - There is no direct connection between the fill hose and the vent hose which would allow fuel out the vent when the tank is anything but full

Don

[coolchange]

Tego and Beta Don...thanks for the thoughts, and I will be checking on the proposed next visit to the boat.

I "know what I know" based on "assumptions" such as: the fuel gauge, which switches with a toggle from Port to Star...I watch a gauge go from full to just about 1/2 and then switch tanks and then add fuel to both...except this time I left one full and am only filling the one showing the most deficit...and here is where the idea of the gauges being for the wrong tanks comes in.

I will keep you posted and heap praise if you guys are on the right track

[jleonard]

I measured my tank depth (port and starboard are the same and they have an equalization line) and made a dipstick using a dowel. Marked at 1/4,1/2,3/4, full.
If I ever doubt my gage (which only reads starboard), that's my backup.

[coolchange]

Hand me the dunce hat...it was the full tank that I was trying to fill. Thanks to Don and Tego for helping me sort out my brain fart.

[tego]

Cool Change, That's what we're here for - to pass on our own experiences so others can learn the
" easy" way. Ben

[RobS]

Hand me the dunce hat...it was the full tank that I was trying to fill. Thanks to Don and Tego for helping me sort out my brain fart.

Well that's about the best boating problem one can have!

[Beta Don]

Glad you found the problem and it was an easy fix - I was hoping it wasn't something like having a tank full of algae. My Dad once ignored my advice to always use a biocide in the little used 80 gallon center tank on his RV puller (it also had a pair of 20 gallon tanks which he normally used) and he later found that when it was 'empty' (the engine wouldn't run on it anymore) it would only hold about 20 gallons when he filled it - The other 60 gallons turned out to be a mass of black algae

I agree that an equalization line would be a great idea . . . . *if* you have a low fitting on each tank you could use for that purpose. That way, whichever tank you were drawing from, both tanks would remain equally full. You could put a ball valve in the line if you liked, so you could disable this feature if you found some need to

Completely separate dual tanks can lead to all kinds of problems - I've read about valve failures which allowed the return fuel to not go back to the active tank, which eventually overfills the other tank and causes a spill. Problems with fuel gauge switching (unless you have two separate gauges) can cause problems too

Don

[Jay Knoll]

Don

That's why I leave my valve's set so I'm drawing/returning from both tanks, and why I fill both at the same time