Fuel Tanks - Draw from Bottom?

[mike_hancock]

I removed my diesel tank for cleaning, and notice that fuel is being drawn from the very bottom of the tank. I thought that fuel is commonly drawn from the top via a drop tube that extends to within 1 or 2 inches from the bottom.

Some have argued that drawing from the bottom actually keeps gunk from collecting, which will usually clog your filters anyway when seas get rough. I see some logic in that position.

What is the consensus? While it is out I am going to install a sending unit and an inspection port for future cleaning. The tanks is stainless steel.

[Cheechako]

hmmm... I see both sides. If it draws from the bottom you will likey get no surprises! It's probably small on the SJ 23 anyway , so clean it out, use good fuel and leave it alone.

[mike_hancock]

Thanks for the reply. I see that I need to change my profile. I just sold the SJ23 and bought a Ranger 33. In any event, the fuel tank is small. I am leaning toward continuing to draw from the bottom.

[Highlander40]

Mike,
The reason that tanks should be plumbed from the top is to avoid potential leaks from fittings below the fuel level. A leak in a top mounted line will let air in and stop the fuel flow. The bottom connection, when it fails, will empty the tank into the bilge!
I have found on my boat that the motion of the boat stirs up the fuel enough that any water or particles get sucked right up the tube. After 10 years and 20,000. nm
no problems. keep your fuel dry.

Carl

[s/v Jedi]

Yes, pick-up pipe from the top is better than a fitting on the bottom (except when you need a bottom connection for gravity feed). But you can take the pick-up pipe almost to the bottom instead of a couple of inches above. This will also increase the range you get (more fuel).

I think the OP is best off not to change anything.

cheers,
Nick.

[jackdaniels9801]

We have a 900Ltr tank, we ran the boat from Indonesia to Australia and the fuel was so dirty that when we had the fuel cleaned in Darwin we got out over 1KG of crap from the fuel. We draw from the bottom, I could not believe that there was so much crap in the tank till we had them cleaned out. Mild steel tanks...bad news. From top or bottom the fuel needs to be clean...we use 2 x fuel filter systems so when one filter gets too full of crap we switch over to the other...hope this helps
John H.

[Highlander40]

John,
I guess you don't always have a choice when it comes to buying fuel.
I learned the hard way, NEVER buy fuel from a yacht club. They pump 2 or 3 gallons at a time and fill up the tank every 10 years or so. In all of new england there are only 3 main choices for me when it comes to fuel and maybe two back-ups.
One mistake that sailors make is trying to use as little fuel as possible. Wrong! That is a formula for major crud build-up. Try to turn over a full tank every month or so. That's way cheaper than fixing tanks and engines.

Have fun
Carl

[jim_thomsen]

Our fuel tank is plumbed from the top, but there is also a fitting at the bottom that can be pumped with a hand pump. I hand pump each time we buy more fuel and a bunch of stuff comes out in the first liter or so, then it's usually clean. I am hoping this is helping keep our tank clean.