Weber carb accelerator pump check valve

[Quickstep192]

I’m planning to replace the accelerator pump check valve in my Webers since the check valves have been marinating in ethanol gas for 2 years.

When I search for replacement check valves, I see that they come on a variety of sizes. The sizes appear to indicate how much fuel they allow to leak back into the float bowl when the accelerator pump is activated. I can not see any markings on the check valves I removed from my carbs.

If I fill my float bowls and operate the accelerator pump, I see fuel spurting back up in the float bowl, but I don’t know if that’s because it’s working properly, or if it’s because the check valves are screwed up from sitting in the bad gas.


I’d sure appreciate any guidance.

[LuftWaffle]

I doubt you need new check valves, they can be cleaned. But you should bite the bullet and strip the carbs completely down, clean and blow out all of the passageways and jets and rebuild with new gaskets and accelerator pump diaphragms. Anything lass you're just playing whack a mole. With that done go thru the initial setup procedures found at the excellent Paul Abbot - Performance Oriented site. Don't overlook the basics like clean fuel, correct fuel pressure and float levels. Note all of the jet sizes during the rebuild so you have a baseline for tuning.

[Quickstep192]

Originally Posted by LuftWaffle

I doubt you need new check valves, they can be cleaned. But you should bite the bullet and strip the carbs completely down, clean and blow out all of the passageways and jets and rebuild with new gaskets and accelerator pump diaphragms. Anything lass you're just playing whack a mole. With that done go thru the initial setup procedures found at the excellent Paul Abbot - Performance Oriented site. Don't overlook the basics like clean fuel, correct fuel pressure and float levels. Note all of the jet sizes during the rebuild so you have a baseline for tuning.

Thanks. I’ve cleaned the check valves and passageways and the car is running pretty well. It’s just the I buggered the screwdriver slot in the check valve and they were really crudded up. This is more of a “while I’m in there” kind of thing. At $17 each, they seem like real cheap insurance. I just need to know which size to get.