Fuel line hose diameter

[Hootch]

Hi all, I recently replaced hoses attached to the inline fuel filter and carburetor to address a slow leak. I wasn't smart enough to save any of the hose I replaced, but the new hose installed is now dripping too, regardless of how tight I clamp. The hose that isn't fitting correctly is: 5/16" / 7.9mm, 3.4 bar. I suspect the internal diameter is the issue. The shop manual I purchased from Vick's doesn't appear to indicate the hose specifications. Can anyone here tell me what hose I should be using? This is a '78 124 but the engine and carb are from a ~1600 cc engine. Also please let me know your source for said hose if it's not something easily found at the local auto parts store.

Thanks, and happy Fall Fiat Driving!

[ORFORD2004]

If 5-16 is too small, use wd40 inside the hose before pushing in.











if 5

[Hootch]

Thanks. The 5/16" feels snug but may be a little too large. The counter help at the auto part store didn't have any other suggestions. I few wraps of teflon tape would likely be enough, but I've never seen that in the context of an auto and assume that would be a really bad approach for a fuel line.

[18Fiatsandcounting]

My recollection is that the '78 spider has a 32ADFA carburetor, and this has two brass hose barbs. One is larger for the fuel inlet. One is smaller for the fuel return. The larger hose should be 8mm while the smaller hose is 7mm but in practice this translates to 5/16" and 1/4" hoses.

So, for the fuel inlet, your 5/16" hose should be fine. Make sure you use a good quality hose clamp and not one of these dollar store cheap ones that tend to bite into the rubber without really tightening.

Another possibility is that the brass inlet into the carburetor body is loose. I wouldn't say this is common, but I have seen it happen. When it does, fuel dribbles out from this connection, and no amount of tightening of the hose will help. Try tapping the brass inlet gently back into the body with a small hammer and see if that helps. If it doesn't help, a carb repair shop might be able to fix it.

-Bryan

[Hootch]

Thanks for the reply! turns out that the barbs had loosened on the inline pressure regulator that sits between the fuel pump and carb. Good to confirm the hose sizing though - I'm sure I'll be referencing that again at some point.