Leaking fuel filter connections?

[atomicjoe23]

I was under the truck the other day and I saw that my fuel filter connections were leaking. . .you shouldn't need teflon tape on AN fittings right, only on NPT fittings correct?

I'm not sure which fittings were leaking the NPT fittings on the NPT-to-AN adapter or the AN fittings, but I just wanted to make sure that I wasn't mistaken when I fix this over the weekend.

Here's the filter I'm using


it has 3/8" NPT inlet and outlet fittings. . .

I'm using thes 3/8" NPT to -6 AN adapter fittings


and these -6 AN fittings I for the fuel line


Thanks for the help!

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[Sparky]

Right or wrong, I have always uses some teflon paste (not tape!) on the NPT stuff. No sealer ever on the AN fittings. I have had bad swivel fittings that have leaked so it might be the fitting itself.

[atomicjoe23]

Any good way to check the fitting itself?

[movindirt]

Have you tried just tightening the fittings? Teflon tape can work with AN fittings but it is not the correct way. The only way to check that I can think of would be to take filter out, only removing from AN fittings. Then cap output side and make small line to allow you to pressurize it and check under water. DON't get CrAZy with the psi!!!! Don't need to hurt yourself. Good luck!

[atomicjoe23]

Good idea. . .Thanks MovinDirt

[racer56]

AN fittings that have been over tightened will start to leak eventually, replace with new ones. Using push-on style hose and fittings on the pressure side of a fuel system is dangerous in my opinion and asking for a fire.

[atomicjoe23]

It's a mechanical fuel pump so those fittings aren't on the pressure side, but good point. . .

. . .the fittings have only been tightened once and after looking more closely at them I think that I didn't tighten the NPT fittings enough. It looks like the fuel was leaking between the fuel filter itself and the 3/8" NPT-to-AN6 adapter fitting.