Please help me understand something.

[Hoosierman]

Please see attached the photograph of the carburetor diaphragm from the accelerator house (perhaps there is a more technical term for it).

My carburetor has horrendous fuel leak out of the housing for the diaphragm. I've done some investigating and removed the accelerator housing obviously- but before that I saw that the gas is not seeping from the gasket, oh no. It's leaking out of a small vent hole at the bottom of the housing. Inside, just below the diaphragm is yet another vent.

Should I be concerned about the diaphragm? I haven't removed it yet, but outward appearances don't show perforation. Or could this be something deeper?

What is the purpose of the holes at the bottom? Is it precisely to keep the housing from filling up with gasoline?

Thanks.

 

[alwaysFlOoReD]

Please see attached the photograph of the carburetor diaphragm from the accelerator house (perhaps there is a more technical term for it).

My carburetor has horrendous fuel leak out of the housing for the diaphragm. I've done some investigating and removed the accelerator housing obviously- but before that I saw that the gas is not seeping from the gasket, oh no. It's leaking out of a small vent hole at the bottom of the housing. Inside, just below the diaphragm is yet another vent.

Should I be concerned about the diaphragm? I haven't removed it yet, but outward appearances don't show perforation. Or could this be something deeper?

What is the purpose of the holes at the bottom? Is it precisely to keep the housing from filling up with gasoline?

Thanks.

Pretty sure the orange thing is like a one way valve. Its been a long time, I think there is a spring that push against the diaphragm which pulls in the gas. Then when you press the gas pedal an arm pushes the diaphragm the opposite way to force gas out the accelerator nozzles. So I would think the bottom hole is the passage to the nozzles. Not too sure if that is a hole at the top.

 

[Uncle Gump]

If you're leaking fuel from the pump cover... the accelerator pump diaphragm is bad.

The orange thing is a one way valve... some carbs use check balls. The orange valve will allow fuel to enter the accelerator pump cavity from the float bowl. It will then seal that passage when you you push the accelerator and the diaphragm pushes fuel out the passages to the pump nozzles.

Nothing inside the pump chamber is not a vent. They're either a fill or discharge ports.

Any vent hole would be in the cover to allow atmospheric pressure to the outside of the pump diaphragm.

 

[Hoosierman]

Looks like a new carb diaphragm is in my future.

Related: When I do the Duraspark Conversion, I intend to hold onto the original carb as a JIC. As I am not used to working with carburetors, I wonder, do people normally just store these as they are found from the vehicle or do they rebuild them before being out into storage?

 

[alwaysFlOoReD]

Looks like a new carb diaphragm is in my future.

Related: When I do the Duraspark Conversion, I intend to hold onto the original carb as a JIC. As I am not used to working with carburetors, I wonder, do people normally just store these as they are found from the vehicle or do they rebuild them before being out into storage?

I store as found and rebuild when needed. Why buy a rebuild kit and install it if the carb doesn't get used.

 

[Hoosierman]

What the heck kind of nut is this that's holding down the carb?

 

[pentode]

Looks like a 12 point nut. A normal 12 point socket should grab that very nicely.

 

[alwaysFlOoReD]

Useful in tight quarters. I see them on front driveshaft ujoint bolts.

 

[Hoosierman]

Yeah, I was being a little flippant because I always see regular six-sided sockets.

Well, as it turns out, the entire underside of the carburetor was leaking fuel. I really wanted to get the truck out for its first real test drive this weekend but since I have the carb off, and I was only a step away from removing the valve covers for the oil leak, I decided to just tear into it and replace the gaskets, repaint the valve covers,and whatever else may need done. It's like working on a heater core- ain't no way In doing all that work to fix one thing without replacing other things, because I don't want to have to do all this again a month later because I didn't. Though in this case, it wasn't hard at all.

And for the record- the new diaphragm did stop the leak at the accelerator pump. It's just a shame the engine is running really rich and the carb is still leaking. :/ oh well.

 

[19Walt93]

Why not clean out the carb and give it an overhaul while it's off? Carb kits aren't expensive and they come with directions. Cyclo makes the best carb cleaner.

 

[Uncle Gump]

Yeah, I was being a little flippant because I always see regular six-sided sockets.

Well, as it turns out, the entire underside of the carburetor was leaking fuel. I really wanted to get the truck out for its first real test drive this weekend but since I have the carb off, and I was only a step away from removing the valve covers for the oil leak, I decided to just tear into it and replace the gaskets, repaint the valve covers,and whatever else may need done. It's like working on a heater core- ain't no way In doing all that work to fix one thing without replacing other things, because I don't want to have to do all this again a month later because I didn't. Though in this case, it wasn't hard at all.

And for the record- the new diaphragm did stop the leak at the accelerator pump. It's just a shame the engine is running really rich and the carb is still leaking. :/ oh well.

Is it dripping down the intake?

 

[Hoosierman]

To answer to 19Walt93's inquiry- I actually will rebuild it for two reasons, one of which is a little more obvious. But also, I've never rebuilt a carburetor in my life- not even a small engine carb. I have all the documentation for it, there is even a vid or two online, plus in the tech library there is a guide. Since I plan to go to Duraspark, it makes the decision all the more easy to make to rebuild the unit. If it doesn't go back onto the engine after this, it's to give me a better sense of what a carb does and how it works at the very least.

Uncle Gump- Here is a photograph I took after I peeled the carb off of the intake. I don't know how much fuel went down into it- it's safe to assume more than I would like- but I do know that it was dripping, absolutely DRIPPING with gas when I pulled it off.