Tank fitting size for supply line... Is it too small?

[LifesBetterWhenYoureBeating]

Hi everyone,

I've recently had a custom diesel tank made to replace the original one (which used 1/4" ID copper pipes for the supply/return lines). In the new one I chose to use hoses instead and thought I could simply use hoses with the same ID of the copper pipes, but the hose fittings for 1/4" hose are only 1/8" ID themselves (unlike the copper fittings), so I'm wondering if that could be a problem? The engine is a Perkins 4.108

Thanks in advance,
Guilherme

[skipperpete]

Originally Posted by LifesBetterWhenYoureBeating

Hi everyone,

I've recently had a custom diesel tank made to replace the original one (which used 1/4" ID copper pipes for the supply/return lines). In the new one I chose to use hoses instead and thought I could simply use hoses with the same ID of the copper pipes, but the hose fittings for 1/4" hose are only 1/8" ID themselves (unlike the copper fittings), so I'm wondering if that could be a problem? The engine is a Perkins 4.108

Thanks in advance,
Guilherme

Yes, its a problem. It might work ok, perkins4-108s are fairly moderate drinkers and have a second fuel pump in the head of the injector pump but a ⅛” fuel line ( which is effectively what is created with ⅛” bore fittings) is something I’d consider un acceptable. I just went to a fair bit of trouble to get a full flow ball valve for a fuel tank shutoff valve to avoid the restriction of the usual ball valves. Another reason to avoid such a severe restriction is that the fittings before the primary filter get first look at any tank debris and its surprisingly easy to block a ⅛” hole and cut off the fuel completely…….if this happened in a situation where you absolutely positively needed that engine to keep running ( crossing a river bar maybe) you could potentially lose the boat.

[Jim Cate]

Can you drill out the hole to a larger diameter? Could you use a short length of 1/4 inch copper instead of the barb fitting?

I agree that 1/8 inch diameter is too small for several reasons.

Jim

[Bowdrie]

Originally Posted by LifesBetterWhenYoureBeating

I've recently had a custom diesel tank made to replace the original one

If you agree with the posts that say the fitting, (~1/8th id.,) is too small, then at that point none of us could offer much of anything useful until we have more info.
What is the tank made of? (can it be worked on easily)
Is the existing fitting screwed or welded in?
Was there any reinforcement added at the position of the fitting to make the tank thickness greater at that spot? (to hold threads).
What about the size of the return line fitting?
Is the supply fitting on top or on a side, (could an inspection plate be added to the top that could incorporate a fitting?
Clear answers will open the door to more definitive options.

[LifesBetterWhenYoureBeating]

Thanks for the comments/suggestions. I've been thinking about what to do and think I have a plan

The tank is relatively small (25 gals), made of 3mm SS (unnecessarily too thick, maybe?). The tube connected to the 1/4 fitting is actually 1/2" ID, so my plan is to have the welder remove the fitting and weld a new 1/4" NPT/NPT elbow (like https://a.co/d/e1AIaNL) and then screw a 1/4" NPT to 3/8" (or 1/2") barb fitting to it. Does that sound like a good idea?

The current fitting for return line is also 1/4", and although I suppose it wouldn't be necessary to replace it I might as well do it. Any thoughts?