Carb vacuum line question

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joevg3

joevg3

10 Year
Joined
Oct 7, 2012
Threads
25
Messages
76
Location
Castle Rock, CO
Hi everyone - I checked this awesome forum for a couple of hours today but still need help. Learned a lot from pin head and fj40 Jim.
My 78fj40 with a 85fj60 2f has been hard to cold start recently. I noticed that a vacuum line from the carb is not connected to anything -my finger is pointing at it in the pic below-and below are three open ports from the manifold. Do indeed to run a line to one of the ports? Should I close them off?

Thanks,

Joe
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One more pic - zoomed out a bit

Vacuum line coming from the top of the carb - not connected to anything.
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Not sure about the carb port but the open ports on the manifold is causing a sizable vacuum leak.
 
It will certainly run better if you TEMPORARILY just cap them (the three coming up from the manifold) off - you've got a big vacuum leak, like surfpig said.

If you have hours and days, you can learn a lot by carefully reading all 889 posts in this thread. It is very useful, with lots of pictures....

https://forum.ih8mud.com/60-series-wagons/188643-my-desmog-thread.html

Rocky
 
Thanks for the thread it's very useful (even though I am not desmogging)- on page 12, I believe the manifold vacuum is referred to as the "gas filter". I will get some plugs today - for the short term fix, does anyone know of a store that sells them? I don't want to hillbilly fix it with duct tape. Thanks again.
 
I would definitely recommend getting those hoses connected properly, but in the short term, you can make a temporary plug that is a step up from duct tape. Just put a golf tee into the vacuum line and cut it flush with the end of the hose.
 
If that is a vacuum line on the carb (the brass tube you are pointing at), since it's above the throttle plates, it would be "Ported Vacuum".

I don't know if it is or is not, because I'm not familiar with your carb.

Ported Vacuum is typically used for distributor advance, it's better than manifold vacuum, because it's high at Wide Open Throttle (WOT).

You can buy a vacuum guage and test it. They are pretty cheap (like $15).

If it's Ported Vacuum, it won't hurt to cap it, but it won't help either. Becuase it's above the throttle plates, it doesn't really affect fuel mixture.

Rocky
 
I believe I found out where the gas filter (vapor not fuel) ports are supposed to go.

1. Vacuum surge tank, I think this is for CA only (i don't have one so I capped it)
2. HAC valve for high altitude - again I don't have it but probably should, so I capped another.
3. ABV - this may be an issue, but I am not sure. My ABV has a vacuum line connecting it to number 1 on my VSV (with the blue VTV). The schematic I am looking at should have the TP connected to number 1 on VSV (with blue VTV). Instead my TP is connected near the VCV line to the manifold...perhaps this is because the engine is a 85 2f and my carb is from the original 78 2f? If anyone knows please let me know!

Right now all lines on the gas filter are capped (with extra line that I had and 3 golf tees - until I can get to the autozone) Probably the best hack I have ever heard of.:clap:

Thanks again for helping.
 
I'm not sure what that gizmo is because I don't have a '78 vacuum diagram, but I do have a '78 carb and the box has a thermally operated vacuum switch that bleeds air from high up in the top cover into something that connects to where your finger is pointed. There isn't much vacuum that high up, so it is not "ported vacuum". The general rule is that if you don't know what a vacuum tube or hose does, plug it so that there are no vacuum leaks. Finding out what it does is a better long term approach.
 
The boxy device on the front of the 78 carb is the HIC valve. There is no vacuum at the valve. The bottom of the valve should be connected to a fitting on the side of the carb base insulator.

It doesn't really matter what year the long block is. Install all the 78 accessories (carb, air cleaner, distributor,AIR pump, EGR...) and hook everything up as normal.

FYI, 78 has one vac hose connected to the manifold fitting. There appear to be no hoses connected in the pics.
 
FJ40Jim said:
The boxy device on the front of the 78 carb is the HIC valve. There is no vacuum at the valve. The bottom of the valve should be connected to a fitting on the side of the carb base insulator.
Click to expand...

In the pic below, I connected the HIC to a port on the side of the carb base insulator (I think properly in blue). Previously, the throttle positioner was connected to the port. The throttle positioner is now connected to VSV 1. Does this look correct? The second pic is a closeup. My emissions documentation doesn't really show this.


FJ40Jim said:
, 78 has one vac hose connected to the manifold fitting. There appear to be no hoses connected in the pics.
Click to expand...

I connected one hose to the ABV (in red) - you should be able to see in the pic. Is that correct?

Again, thank you everyone!
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I believe my pictures above show it setup according to the diagram, thank you. I am by no means an expert. I am still not sure if I have the HIC properly connected -
 
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