Fuel Leak from Carburetor

[65 Mustang]

Hey Guys,

I noticed fuel leaking from the front of my carburetor (Autolite 1100) this evening. I have an inline filter that screws into the front of it. The leak seems to be coming from the underside of the filter where it screws into the carburetor. It only occurs when the engine is running and squirts out a bit. My first instinct is to replace the inline fuel filter. Could there be other issues, however, that would be causing fuel to leak at that spot? Any info would be great. Thanks.

 

[ludwig]

Did you wrap it with teflon tape before you screwed it in? Gotta make sure there is no tape past the threads to get in the fuel. If you have a rubber fitting at the filter, you might have a crack in the rubber, like where it is clamped to the inlet side of the filter.

 

[schaferstephen]

Just to state the obvious...

Are you sure it's tight enough?

This is a toughie. I had the same issue when I replaced a Holley with my current Autolite. I had to tighten it down pretty good, which made me nervous because if you overtighten... You're gonna break some threads and be SOL. Having said that, you do have to snug it down pretty well. Try putting a wrench and just tightening gently (with the engine running) and see if that stops your leak. If now, I'd recommend a small SMALL amount of RTV as opposed to teflon tape, just because it's been my experience that gas will eventually eat through teflon tape. But don't go by me, I broke a shoelace this morning

Good luck buddy!!

 

[65 Mustang]

Thanks for the info. Where exactly do you place the RTV silicone? Is it in the small gap between fuel filter and carburetor?

 

[oldgrezmonke]

Any sealer you use would be on the filter threads starting a couple threads back from the leading edge . Some fuel filter threads are like pipe threads slowly increasing in diameter so that eventually there is a good tight leak-free fit . But on our many years old parts there could be worn threads which would need a sealer . I have used teflon on fuel fittings with no problem . If you try the RTV - be sure it indicates that it tolerates constant exposure to gasoline .

 

[ludwig]

Ditto oldgreezmonke. If you start the teflon back from the outlet, it will not get contaminated or contaminate. It's there to seal the threaded walls.

I believe our brass fittings are mostly parallel thread, not tapered thread like water plumbing fittings. Many of them achieve a seal by bottoming out on some surface or by the tension of dissimilar metals where one is softer than the other and conforms to the harder surface. If you use a thread sealer, it will work its way back on the fitting being screwed in. But you have to be careful not to get any of it - tape, paste, okum, pitch - on the end of the fitting where it is not wiped by the threaded walls that you insert it into.

 

[65 Mustang]

Thanks for the info.

 

[Explorer]

My bet is the fitting has cracked the case. While commonly refered to as a sealer, teflon tape is a lubricant, not a sealer. Good luck and hopefully I'm wrong.