'72 FJ40 Emissions Control Device~Advice

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Millardo

Millardo

'72 FJ40
10 Year
Joined
Sep 7, 2011
Threads
57
Messages
493
Location
Long Beach, CA
Website
forum.ih8mud.com
The sticker on top of this Evaporative Emissions Control Device is not legible. Can someone please confirm what I think to be correct as to the connections?

Very much appreciated.

1) Carburetor
2) Intake Manifold
3) Diaphragm
4) Distributor
5) Charcoal Canister


3/1972 FJ40
EvapEmiss.webp
 
maybe look at an fsm? or in the faq? or search it.... its here somewhere I know it
 
Emissions control device on top of drivers side fender

Millardo,
This one I've got, my early '72 FJ bretheren.

1) To diaphragm that actuates the linkages on the back side of carburetor.
2) To port on carburetor base plate.
3) To hex shaped fitting on intake manifold in front of carburetor.
4) To Distributor vacuum advance.
5) To steel line that runs along top of firewall then to the forward one of the 2 ports on the top of the evap canister mounted low on the passenger side of the engine compartment.
 
Emmissions connections

I should add that that is how mine was hooked up and it appeared to not have been messed with in many decades. The info did not however come from any Toyota literature.
 
Does this need to be hooked up? How can you tell if it stopped working? What would happen if it was removed? How would you remove this and keep the engine from having vacuum leak issues?

Sorry I just figured this thing has probably stopped working correctly long ago, and am trying to figure out what to do with it on my, new to me, rig.
 
Hey Sparky,

This little guy is called a "vacuum switching valve" and, assuming you have a 72 model year, is one of six components of the Improved Combustion System (aka - emissions control components). The other components are a small black computer box (the speed marker) located under the dash on the firewall inside on the driver's side, a modified carburetor, a modified distributor with a vacuum retard, and a speed detector (associated with the speedometer). If the speed marker or the speed detector stop working, the vacuum switching valve will sit there in its "off" position and vacuum from the manifold and carburetor riser will theoretically not do anything. When it’s turned on, and the vehicle is traveling above 14 mph, the vacuum pulls vapors from a vapor storage case and into the port below the carburetor to be burned during ignition. Below 14 mph the vacuum switching valve activates the diaphragm on the carburetor allowing the throttle to fully close. Without the vacuum to that diaphragm the throttle will stay open and the engine will race.


That being said, the device does do things, all of which are related to emissions control. However, if it has been inoperative for a while, the previous owner probably tuned the engine to run smoothly without the valve by disabling the carburetor diaphragm linkage, or, as I did, routed the hoses to pull a vacuum on the carburetor diaphragm full time to allow the throttle to close and prevent the engine from racing regardless of the speed.

If yours is working, when you engage the clutch at highway speed, your engine will not return to idle speed until it falls below about 14 MPH. It's quite noticeable and rather annoying. If it's not working, when you depress the clutch and take your foot off the accelerator, your engine will return to idle regardless of your speed.

The bottom line is that your Cruiser can run fine without it so long as you make allowances for those components that are affected by the valve under normal working conditions. Regarding vacuum leaks, on a 72 model, there are only two ports that need to be blocked off: one on top of the manifold forward of the carb and the other just below the base of the carburetor at about the same level as the vacuum switching valve and pointing towards it.


Hope that helps.
 
Kayaker said:
Hey Sparky,

This little guy is called a "vacuum switching valve" and, assuming you have a 72 model year, is one of six components of the Improved Combustion System (aka - emissions control components). The other components are a small black computer box (the speed marker) located under the dash on the firewall inside on the driver's side, a modified carburetor, a modified distributor with a vacuum retard, and a speed detector (associated with the speedometer). If the speed marker or the speed detector stop working, the vacuum switching valve will sit there in its "off" position and vacuum from the manifold and carburetor riser will theoretically not do anything. When it’s turned on, and the vehicle is traveling above 14 mph, the vacuum pulls vapors from a vapor storage case and into the port below the carburetor to be burned during ignition. Below 14 mph the vacuum switching valve activates the diaphragm on the carburetor allowing the throttle to fully close. Without the vacuum to that diaphragm the throttle will stay open and the engine will race.


That being said, the device does do things, all of which are related to emissions control. However, if it has been inoperative for a while, the previous owner probably tuned the engine to run smoothly without the valve by disabling the carburetor diaphragm linkage, or, as I did, routed the hoses to pull a vacuum on the carburetor diaphragm full time to allow the throttle to close and prevent the engine from racing regardless of the speed.

If yours is working, when you engage the clutch at highway speed, your engine will not return to idle speed until it falls below about 14 MPH. It's quite noticeable and rather annoying. If it's not working, when you depress the clutch and take your foot off the accelerator, your engine will return to idle regardless of your speed.

The bottom line is that your Cruiser can run fine without it so long as you make allowances for those components that are affected by the valve under normal working conditions. Regarding vacuum leaks, on a 72 model, there are only two ports that need to be blocked off: one on top of the manifold forward of the carb and the other just below the base of the carburetor at about the same level as the vacuum switching valve and pointing towards it.


Hope that helps.
Click to expand...

this is the information i have been looking for. i had a general idea of what the vacuum valve did but i had two problems. first my timing would be fine at idle but as soon as the engine revved up then returned to idle it would not idle smoothly and would stall. i had managed to find out that the 1972 model year had a vacuum-retard distributor and everything was hooked up properly but my speedometer doesn't work. so now this explains why the timing advances with centrifugal weights, but does not retard with vacuum. if i hook up a direct vacuum line to the distributor will this fix my problem? i have removed and replaced the entire distributor, lubricated it and everything is in working order with new contact points. i thought the problem might be that the plates or weights had seized but they hadn't.

problem number 2 is the evaporative canister is in the middle armrest/seatback which seems like a terrible idea to me. on a hot day in the summer the fumes are overwhelming (likely because half the evap system isn't working) i am going to remove it and install it in the engine bay or the parts pile behind the shop. as long as the tank is vented and all lines lead somewhere it should not create a problem?

thanks for the help.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom