Fuel pickup tube dimension?

[andreas.mehlin]

Does it matter if the fuel pickup tube in a tank is bigger than the size of the diesel intake nipple on the fuel pump?

Having a tank made and need to get some material for the fuel pickup tube.
Building the tank in stainless. Should I use a plastic tube like nylon or have a stainless tube welded on? My connections will all be installed on top of the inspection port/lid....

[tkeithlu]

Be aware that given that it's a diesel tank, you can gravity feed from the bottom rather than lifting out the top.

The only consequence of a larger tube, if that is what's convenient, is slightly longer priming time for the lift pump. It should not be a problem. You are not changing the height of the lift.

Use the stainless pickup tube, then shift to rated fuel hose for the run to the pump. If the tube is coming out the top, bend it over so the hose does not put a lateral force on it. The pick up tube cannot get quite the last bit of oil, and that's good, because that's where the junk accummulates. A drain plug or valve at that bottom allows you to remove that junk (water, usually).

[Lepke]

If you're building a tank, include a drain and valve. If you're going to use a pickup tube, make it replaceable. Someday if you're sorting a fuel problem you can pull the tube to see if it's clogged or corroded away. If there's room, include a clean out port.
If you want the tank to last the life of the boat, use a internal diesel tank coating. I do it to any tank I build or repair. My current boat has 78 year old steel tanks.

[RaymondR]

On my old boat my fuel tank was in the keel and consequently I had to have a standpipe. It went all the way to the bottom of the tank but went into the tank through a gland to allow me to adjust the height of the tube above the bottom.

The standpipe tube was 1/2" pipe and I also could fit a Finsbury pump on to the top and push it down to the bottom of the tank to pump any water or sludge out.

[GordMay]

Originally Posted by Lepke

... If you're going to use a pickup tube, make it replaceable. Someday if you're sorting a fuel problem you can pull the tube to see if it's clogged or corroded away ...

Originally Posted by RaymondR

On my old boat my fuel tank was in the keel and consequently I had to have a standpipe. It went all the way to the bottom of the tank but went into the tank through a gland to allow me to adjust the height of the tube above the bottom ...

Raymond's 'gland' also allows for Lepke's remove/replace-ability.
Both, good ideas.

[Squanderbucks]

Have a SS if possible female NPT fitting welded into the top that allows a male fitting possibly a 90 degree fitting screwed into it. Have the shop weld the tube onto the
Screw-In portion of the removable fitting. Also I recommend having the male end of the fitting be a flare connection. Either JIC or SAE doesn’t matter.
This way the tube can be removed if needed in the future and hoses easily connected and removed for hose replacement.
Do exactly the same for the Return fuel fitting. Many recommend a short angled “tail” pipe on the return that shoots the fuel toward one of the tank walls. It reduces air bubbles in the fuel. And directs return fuel being put right back into the area of the pickup.