2F Secondary not opening

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Jul 16, 2013
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269
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Montana
Ok, I have done a lot of reading as there are many posts on this, but still can not get the secondary to open.
1982 FJ45 wtith a 2F.
Have done the paper clip test and the diaphragm is not moving (only the mechanical portion)
Vacuum is at 15
Adjusted the tab to help with the initial mechanical opening of the secondary
All vacuum hoses are fairly new
Disassemble the diaphragm and it looks really good, like almost new.
Blew air through the vacuum port for the diaphragm and its clear.

What else should I check?

Thanks

Guy
 
Joined
Jul 16, 2013
Messages
269
Location
Montana
Ok, I have done a lot of reading as there are many posts on this, but still can not get the secondary to open.
1982 FJ45 wtith a 2F.
Have done the paper clip test and the diaphragm is not moving (only the mechanical portion)
Vacuum is at 15
Adjusted the tab to help with the initial mechanical opening of the secondary
All vacuum hoses are fairly new
Disassemble the diaphragm and it looks really good, like almost new.
Blew air through the vacuum port for the diaphragm and its clear.

What else should I check?

Thanks

Guy
Bumping this back up to the top, as I have a trip coming up on Wednesday and would like to have the secondary in the carb working. Thanks
 
Joined
Jul 16, 2013
Messages
269
Location
Montana
Bumping this back up to the top, as I have a trip coming up on Wednesday and would like to have the secondary in the carb working. Thanks

Ok, I have done a lot of reading as there are many posts on this, but still can not get the secondary to open.
1982 FJ45 wtith a 2F.
Have done the paper clip test and the diaphragm is not moving (only the mechanical portion)
Vacuum is at 15
Adjusted the tab to help with the initial mechanical opening of the secondary
All vacuum hoses are fairly new
Disassemble the diaphragm and it looks really good, like almost new.
Blew air through the vacuum port for the diaphragm and its clear.

What else should I check?

Thanks

Guy
Just checked that the mechanical portion activates when pressing the gas pedal to the floor, and it does.
Replaced the diaphragm with a new OEM one.
Made sure the vacuum passage from the secondary in the carb to the diaphragm is clear (blew compressed air through it).

I can make the diaphragm work with out the spring by sucking through the vacuum orifice, but not once I put the spring in.

If anyone has any advice, it would be very much appreciated. @Pin_Head or @65swb45 or @3_puppies.

Thanks

Guy
 
Joined
Jul 16, 2013
Messages
269
Location
Montana
Perhaps you have too strong of a spring in the actuator can.
Thanks for the reply. I bent the tab for the mechanical actuator, it's to the point that if I bend it more, the secondary stays open even when not pressing the gas pedal. So to clarify, it does not open without pressing it, but would if I bend it more.
I did check the spring and bought a set of secondary spring and looked at using the white spring per another post's suggestion, but even the white one was a stronger spring than the one I have. Can easily suck on the diaphragm with my mouth and get it to move.

Maybe it's time for a carb rebuild. I'm at a lose as to why it does not open.
And thanks for your videos and support to the Cruiser community.

Guy
 
Joined
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15,301
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OC, CA
If there is nothing wrong with the can and the secondary plate opens up, then the vacuum signal is not getting to the can. Did you use any gasket cement on the bowl / base Gasket? That can clog the vacuum channel. Does the shaft turn freely?
 
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If there is nothing wrong with the can and the secondary plate opens up, then the vacuum signal is not getting to the can. Did you use any gasket cement on the bowl / base Gasket? That can clog the vacuum channel. Does the shaft turn freely?
Thanks. I bought the car with this carb as is. It was working a couple of years ago. Then I decided to check it as it seemed to be lacking power. I can’t see any sign of gasket cement. The shaft turns free and smooth. I did blow compressed air through the vacuum passage and appears to glow freely. Hmmm. The mystery continues.
 
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I spent a lot of time troubleshooting my vacuum secondary recently. A couple of things i found out.

1. Vacuum secondary needs as much vacuum as possible to open. Between the return spring and torsion spring it takes a lot of vacuum to get it to open.
2. Test the secondary with a vacuum pump directly to make sure it's not leaking.
3. Make sure you have the gasket between the vacuum can and the carb. If there's a leak there it will prevent it from opening.
4. 15in vacuum might be a little low. Mine won't open when the vacuum is too low, I don't know what the minimum vacuum is but when driving I need to be at a certain RPM (40mph in 4th gear) before I can get it to open. I want to say it was around 16-17 in, any lower and the engine just bogs down.
5. Your venturi's might be loose. My first carb the venturis were loose in the bore so I think it just wasn't generating enough vacuum in the secondary circuit until I swapped carbs
 
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Joined
Jul 16, 2013
Messages
269
Location
Montana
I spent a lot of time troubleshooting my vacuum secondary recently. A couple of things i found out.

1. Vacuum secondary needs as much vacuum as possible to open. Between the return spring and torsion spring it takes a lot of vacuum to get it to open.
2. Test the secondary with a vacuum pump directly to make sure it's not leaking.
3. Make sure you have the gasket between the vacuum can and the carb. If there's a leak there it will prevent it from opening.
4. 15in vacuum might be a little low. Mine won't open when the vacuum is too low, I don't know what the minimum vacuum is but when driving I need to be at a certain RPM before I can get it to open. Otherwise it just bogs down.
5. Your venturi's might be loose. My first carb the venturis were loose in the bore so I think it just wasn't generating enough vacuum in the secondary circuit until I swapped carbs
Thanks. Great info. Won’t be able to trouble show more till the weekend, but will make sure to post what I find out.
 
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moncton., nb. canada
Pin Head your a genius....thanks to you and your you tube video ., you gave me the courage to tackle the overhaul of my carb...with success!...fixed the problem i had......dirty carb.....will check my secondary tomorrow to see if in need of adjustment ...i hadn't seen this video about the secondary adjustment when i rebuilt my carb....the diaphragm was changed at overhaul but the actual opening of the butterfly wasn't .i think its ok but will check thanks again
 
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The vacuum secondary runs off of Venturi vacuum, not manifold vacuum. Moreover, the vacuum has to be high in both the primary and secondary venturis at the same time. There is a vacuum passage between the primary and secondary bores so that if one has no vacuum, the vacuum in the other will just pull air out of the one with low vacuum instead of pulling the operation rod inside the can. This causes the secondary to close immediately after the primary closes. The air flow through both primary and secondary has to be high enough to generate the necessary vacuum.
 
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or you can cheat and mechanicalize it. The self tapper next to the spring in the pic opens the secondaries at about 1/3 throttle. I actually like it like this, so I left it.

IMG_20210812_120352.jpg
 
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Congratulations!

So what do you think the problem was? It wasn’t clear from the descriptions And it might help someone else.
I'm not 100% sure. I did realized that the new diaphragm I had put in was not on quite right. But that does not explain why it was not working before I changed the diaphragm. Maybe the vacuum passages for the diaphragm were not quite clean all the way? or the sealed gasket at the between the diaphragm and the carb was leaking. That is all I can think off.
Guy
 

devo

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I asked that question because my Toyota carb mechanic told me it can? I mentioned it after my rebuild that the paper clip test revealed that the diaphragm was not pulling? After watching @Pin_Head video it seems that the diaphragm is essential to the secondary opening.


devo
 

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