1978 California carb question (1 Viewer)

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Joined
Dec 1, 2008
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Location
Camarillo, CA
I just obtained a California 1978 FJ40 for restoration and I'm going through the emission lines/hoses. Can anyone tell me where the vacuum lines on the top of the carburetor are supposed to run? The nipples are outlined in red in the photo.
Thanks,
Ray

Carb vacuum lines.JPG
 
Top one (8) should be the power valve. Not sure about the bottom one. The 1978 emissions manual should have a vacuum hose routing diagram.
 
Where is the "power Valve"? I need to know where to run a vacuum line from the nipples to? In the emissions pages I've seen, unless I'm missing something, they don't cover these two lines. Are they in this diagram? If so I can't tell.

smog cal_detail.jpg
 
Looks like they're there. Am not sure why the 8 looks like it's connected to the ABV, on my CA-spec '77 it's connected to the VSV, from what I recall. The lower one appears connected to the VSV, and may be some kind of valve to burn fuel vapors from the charcoal canister. Your VSV is year- and CA vs FED-specific, make sure you have the right P/N for that.

On my '77, the power valve stays open until the truck is warmed up to richen the A/F mix. Once it hits operating temp, the VSV pulls vacuum on the power valve to keep it closed until it's reopened by the power valve switch on the gas pedal at WOT. FWIW mine doesn't do that right now, I'm chasing a ground fault on the switch.
 
I think that you are confusing the line from the ABV that goes to the air cleaner in the diagram, it doesn't go to the carburetor. The #8 nipple on the carb (if that's it in the diagram between the air cleaner and the VTV blue arrow) does look like it goes the the VSV.

This still doesn't account for the top nipple (or where the Power Valve is).

They are year specific. Does your 1977 carburetor have the two nipples that I circled in the picture? If so, where do the lines run?
Thanks,
Ray
 
Ah, ok. The CA '77 doesn't have a vacuum line between the ABV and air cleaner. Can't remember offhand where the ABV one goes, might go directly to manifold vacuum.

The '77 has the top nipple, but on my carb that top one is marked #8 and is the power valve, going to the VSV. It does NOT have the lower nipple (marked #8 on yours) or the return line to the carb from the charcoal canister. There should be a legend of what each VSV nipple does on the top of the VSV itself.

I will say there is hope to pass CA smog with a recently rebuilt carb. Even if everything is in place, most of it probably isn't working to full effect, and mine still passed fine.
 
I appreciate your help. But does anyone have a 1978 California carb who can look, or can anyone tell me what the top nipple on the carb goes to?
Thanks,
Ray
 
I can’t tell you where the top line goes but the bottom port routing is shown in the diagram above. The hose does a little u-turn and connects to the top portion of the port that’s positioned near the screw in the lower right of your picture. Maybe 3 inches of hose are needed. On a fed spec ‘78 carb the top port is deleted. The rest looks the same, however.
 
I can’t tell you where the top line goes but the bottom port routing is shown in the diagram above. The hose does a little u-turn and connects to the top portion of the port that’s positioned near the screw in the lower right of your picture. Maybe 3 inches of hose are needed. On a fed spec ‘78 carb the top port is deleted. The rest looks the same, however.
Thanks fyton2v, is your 1978 FJ40 California, or a Federal Spec? If its California, does it have the upper nipple?
 
Thanks fyton2v, is your 1978 FJ40 California, or a Federal Spec? If its California, does it have the upper nipple?
It's fed spec. It happens to live in CA though. My carb looks pretty similar ...

Nevermind. I looked here and they're not at all the same. I have an emissions manual that should cover the California vacuum hose routing. I'll try to snap a pic of that tonight when I get home.
 
Same photo as above, but here are a couple more from the emissions manual. I'd plug it and move on :).

IMG_0677 Large.jpeg


IMG_0678 Large.jpeg
 
I'm pretty sure I have an extra 78 CA-spec carb in storage - happy to dig it out if of interest or help to anyone...
 

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