83 AMC Eagle return fuel check valve replacement.

[The OLD Man]

I was able to purchase a 4an size fuel return check valve from Improved Racing to replace one hidden in hose. The valve has a .04 crack pressure. Seems to be working fine. Can be ordered with barbed fittings.


https://www.improvedracing.com/high-flow-low-cracking-pressure-flapper-check-valve-6.html

[KootenayKev]

Can I ask what problems this eliminates? I read earlier today the return line can siphon the carb while sitting? Can it interfere while driving? Say up a steep grade for example?

[89 MJ]

Can I ask what problems this eliminates? I read earlier today the return line can siphon the carb while sitting? Can it interfere while driving? Say up a steep grade for example?

Not to my knowledge, but I've got a different carburetor. I got rid of the fuel line check valve and the line won't siphon the carb dry even after a week of sitting. My car is wheeled on steep grades and driven up steep hills on the road, completely fine.

[vangremlin]

If anyone is looking for one, I found these one ebay, for use with regular fuel hose

https://www.ebay.com/itm/314315356308

[The OLD Man]

This prevents Vapor Lock on hot days. Car wont start. Low PSI return 0.4 crack pressure one way to tank. This prevents any return. The cheap valves on Amazon are too high of a crack pressure, meaning opening the valve. The original one hidden inside of rubber fuel line was typically thrown away because a lot of people could not see it as it was hidden. I believe the original one was a 1/2 psi return crack pressure opening. I'm not a expert but this is what I got from looking into it.

[AMC of Houston]

Also a problem with some aftermarket fuel filters for our Eagles.  That little 1/4" line out (the one that should be at the 12 o-clock position to let vapor escape) is supposed to have an orifice built into it.  Some don't.  Peek into it and you'll see it if its there.  The Wix units I use all seem to have them - so far, at least until some bean counter decides they aren't needed!