Under-deck fuel tank - where's the hose connected? (incredible diagram)

[Buzz Killington]

First, I apologize for this more general question here - but it involves an old boat (my '68 Thunderbird) and I figure many of you guys have had the (mis)fortune of tearing up your decks in your old boats.

This is a top down view of the rear of the boat (please contact me for prints! ):

I have an ancient, likely original fuel hose coming out of a small hole in the top/back of the bilge. It MUST be replaced before use...it is literally coming apart in my hands. However, I cannot get access to the point at which it connects to the tank in order to replace it. Immediately behind the bilge is about 4" of fiberglass deck, then it turns to plywood. From what I gather from the previous owner, the deck was redone and I have no interest in tearing it up all the way at this point in the resto. PO simply used a 6 gallon portable tank (for a 140hp Merc?!).

My question for you guys is where do you think I should cut a small "panel" to try and get to the tank/sender? I posted this in the Formula/Thunderbird forum and I did not get a response. I'm guessing somewhere immediately next to the fiberglass, but I have no experience with old boats/permanent fuel tanks and so this is purely a guess. Any "educated" guesses would be greatly appreciated!

Also, any suggestions on cutting into the plywood without getting into the tank would be appreciated. I was thinking about trying to find a larger cutting wheel for my dremel. I don't know if I can control my DeWalt angle grinder enough to do this.

Dave

 

[Mark42]

Re: Under-deck fuel tank - where's the hose connected? (incredible diagram)

Use a circular saw, set the depth gauge to just less than the deck surface and make the cuts. Then go back with razor knife for the last 1/8 or 1/16".

I would cut a hatch. But before doing so, look at the common size deck access plates that can be fit back in. Cut an odd or too big hole, and you just bought a very expensive deck access plate.

 

[Greg Mrozinski]

Re: Under-deck fuel tank - where's the hose connected? (incredible diagram)

I agree with Mark but make sure it is one that can take your weight and constant walking on.

 

[Paul eagen]

Re: Under-deck fuel tank - where's the hose connected? (incredible diagram)

Pictures may help so that someone can give you an educated guess. If you know the direction that the hose goes to you could use a 1/2 in drill bit to drill a hole in the area then shine a light in the hole or even from another spot, if you have access, then you may be able to see where the sending unit is. But if the fuel tank hasn't been used in a long time you may have no choice but to pull it up. There should also be wires going to it, two ground wires, one to the sending unit and one to ground the tank, then one 12v + to the sending unit.

 

[Buzz Killington]

Re: Under-deck fuel tank - where's the hose connected? (incredible diagram)

Pictures may help so that someone can give you an educated guess. If you know the direction that the hose goes to you could use a 1/2 in drill bit to drill a hole in the area then shine a light in the hole or even from another spot, if you have access, then you may be able to see where the sending unit is. But if the fuel tank hasn't been used in a long time you may have no choice but to pull it up. There should also be wires going to it, two ground wires, one to the sending unit and one to ground the tank, then one 12v + to the sending unit.

Thanks for the suggestions guys.

There is one wire coming out of the same hole, what appears to be a heavy-gauge ground that is connected to the transom. There were only three gauge openeings cut - one was a speedo, one was a tach, one was an old Mercury water pressure gauge - so if there ever was a fuel gauge it was an add-on that is long-since gone.

 

[jonesg]

Re: Under-deck fuel tank - where's the hose connected? (incredible diagram)

Save yourself all the agonizing because its a sure bet the tank is shot anyway, the fill hose is shot too.
If the tank is stainless, it will still have to come out for proper cleaning.
Cut the deck open and replace it all or do like the previous owner but with a bigger tank.

When I replumbed mine the fill hose was dated 1986 , but my boat was made in 74, so it was already done 20 yrs ago and it was due again by 2008.
Its a beach of a job, the deck usually has to come off to do it right.

 

[Mark42]

Re: Under-deck fuel tank - where's the hose connected? (incredible diagram)

Dave, Seeing as your boat is from 1968, I agree that the fuel tank may need replacing as well as all the fuel lines, fill and vent. Tanks and marine grade fuel line are expensive. So much so that some people use auto grade fuel line, and other auto grade hoses (like radiator for fill hose). Don't even think about doing that. The fuel system parts can be had for reasonable prices, but it takes shopping around. Depending on what you find when the deck is cut up, if the fuel tank needs to be replaced, and it can be replaced with a "standard" aftermarket belly tank, then most places will have a good price. If it takes a special shape, then check these guys out, they were the only place to get me a special size tank at a reasonable cost: Ocean Link Inc.

http://www.oceanlinkinc.com/tanks/gas-diesel.htm

Search for tank sizes by gallons or by dimension.

I buy fuel fill, vent and feed hose from http://foreandaftmarine.com/FUELHOSECERT.HTM they have the lowest prices.

 

[Buzz Killington]

Re: Under-deck fuel tank - where's the hose connected? (incredible diagram)

Thanks for the info guys.

If the tank is aluminum it ought to be good, eh? Maybe need a cleaning, obviously. I'm hopeful that the PO cleaned it when he redid the deck, because the ground wire is new. I'll dump a few gallons and and slosh it around and see what comes out.

 

[renovator]

Re: Under-deck fuel tank - where's the hose connected? (incredible diagram)

I might be able to save you a lot of aggravtion when changing the hoses.
once the end locations are found and without damaging the hoses any further, try a splice,(coupling) inside the hose end with a tight fit to anew marine grade hose and pull gently the old hose while feeding the new hose through the passage of the old one. 9 out of ten ussually works .