Vacuum Question

[70 FJ40]

First off, my 2F is desmogged. Its running really quite well for me but it recently started making a high pitched squeeling sound. Pretty quiet at first but its getting louder. I first thought it might be a bearing on my alternator or something. If I reved the motor slightly it would go away, but not anymore. I have figured out though, its a wistle caused by vacuum. I've got a vacuum hose running from the base of the carb over the top to the PCV valve. This hose is getting sucked in to where its collapsing on itself. Do I just need a tougher hose or have I got too much vacuum?

 

[bhsdriller]

Can't have too much vacuum, wrong type of hose you need pcv hose rated for the vacuum

 

[70 FJ40]

Thanks @bhsdriller Didn't think I could have too much vacuum. Not sure, but I think this hose was on the truck when I got it. It had lots of vacuum leaks before all the work I did to it so it wasn't a problem then.

 

[fjc-man]

That PCV valve could also be contributing to the issue.

 

[70 FJ40]

Ya, I have no idea how old it is.

 

[Spike Strip]

PCV valve AND grommet are still available from Toyota and MUD vendors.

You need PCV rated hose. NAPA will have it.

Post a picture of your distributor top. Curious. You're missing bits that could be harming the dissy, if you still have the stock distributor.

PCV Valve - Fits E-1987 F/2F 4x/5x/6x Applications (ENGPCV61010JP)

PCV Valve - Fits E-1987 F/2F 4x/5x/6x Applications (ENGPCV61010JP)

cruiserteq.com

PCV Valve Grommet - Fits 9/1969-7/1987 4x/5x/6x F/2F Engine Applications (ENGPCV18180)

PCV Valve Grommet - Fits 9/1969-7/1987 4x/5x/6x F/2F Engine Applications (ENGPCV18180)

cruiserteq.com

 

[70 FJ40]

Here's my distributor.

 

[Spike Strip]

I don't think your desmog was done properly.

#23 in the pic (and assorted hoses) is missing, and because of that, there's no fresh air being drawn into the dissy - You can see the ports are capped off. I'm also guessing valve #50 is missing which regulates the air flow.

That 'T' fitting (#23) is long discontinued but vintageteqparts.com has reproduced a stainless steel version.

The guts of the electronic distributor corrode quickly without the air circulation because if ionization.

Also, I believe the vacuum advancer has the wrong diaphragm capped, but I'm not sure about that as I'm not desmogged. I think it's the inner chamber is advance and the outer is vac retard. You keep both if your HAC is present and functional and you still have the violet BVSV

Can anyone confirm which section of the Vac Advancer is advance ?

 

[70 FJ40]

Its very possible my desmog is not done correctly. The PO did it initially but it was really incomplete. I did it a little differently when I put it back together with a new haed gasket. I thought I had done it correctly from what I could gather here on mud. If something is wrong, I'm more than grateful if someone is willing to tell me what I have wrong.

 

[CruiserTrash]

I don't think your desmog was done properly.

#23 in the pic (and assorted hoses) is missing, and because of that, there's no fresh air being drawn into the dissy - You can see the ports are capped off. I'm also guessing valve #50 is missing which regulates the air flow.

That 'T' fitting (#23) is long discontinued but vintageteqparts.com has reproduced a stainless steel version.

The guts of the electronic distributor corrode quickly without the air circulation because if ionization.

Also, I believe the vacuum advancer has the wrong diaphragm capped, but I'm not sure about that as I'm not desmogged. I think it's the inner chamber is advance and the outer is vac retard. You keep both if your HAC is present and functional and you still have the violet BVSV

Can anyone confirm which section of the Vac Advancer is advance ?

View attachment 4126102View attachment 4126103

You're correct on the advancer diaphragms. The inner one is vacuum advance from a ported outlet on the carb - that should be connected. The outer diaphragm is for the 7 degrees of static advance from the HAC diaphragm. @70 FJ40 with your location in Eastern Oregon, keeping the HAC is a good idea. If you live in lowlands and go wheeling up in higher elevation (or vice versa) the HAC really is to your benefit.

This is what drives me nuts on desmogs. Guys are always saying (and to be clear, not you OP) "Thank god I ripped out all that dumb tree hugging hippie vacuum line crap and now I got tons MO' POWA'!" without first learning what any of it does. A lot of it is beneficial. For example, Spike pointed out the distributor venting system here being capped off. It's good to have that so the inside of the dizzy doesn't corrode and seize up. It doesn't affect the engine running. Having the proper vac line running to the proper advancer diaphragm will help the truck not run like garbage when you're hammering on the throttle. Keeping the HAC if you live in an area where go above and below 4000' elevation will help the truck run well down low and up high without having to get out and change carb jets. Even stuff like EGR - if you remove it there can be benefits, but also drawbacks - learning how to manage or tune for those drawbacks is just as important as ripping it out.

The Emissions Manual is in the Resources section here on Mud (there's a tab at the top of your screen). It's good to familiarize yourself with all of the systems then go back and look at how your engine bay is plumbed.

 

[Spike Strip]

Completely agree. A bad desmog is worse than all the emissions equip being left alone. Even something as simple as the HIC (Hot Idle Compensator), that all carb'd vehicles have in one form or another, and non-functional in the above example, can make the truck run and idle like crap when missing.

 

[CruiserTrash]

Completely agree. A bad desmog is worse than all the emissions equip being left alone. Even something as simple as the HIC (Hot Idle Compensator), that all carb'd vehicles have in one form or another, and non-functional in the above example, can make the truck run and idle like crap when missing.

I swear the HIC/HAI valve on the underside of the air cleaner was never designed right in the first place. My theory is that 100% of these trucks have been running around sucking in hot air via the HAI flap at all times. And the extra cool air from the HIC (or whatever that system actually does), isn't a thing. Maybe all the valves went bad right away or something, but I remember testing a bunch and starting a thread on it, I came to the conclusion that they were designed incorrectly.

 

[Spike Strip]

The HIC on these is very important since the under hood temps are so high, particularly with modern crap gasoline. The function is to lean out the mix when engine temps/ambient temps are high because hot air is less dense and heat soak can cause hot gasoline that either boils or increases vapor load that pushes out more gas. Modern gas designed for fuel inj is even more prone to this in obsolete carb'd systems. It's not an emissions component, it's a drivability component.

The problem with the FJ60 HAI/HIC valve, if you can call it a problem, is that it was designed for multiple functions. It took me years to figure out why my truck would all of a sudden run rich (on my A/F meter) when it was warm and I eventually traced it to the inoperative HIC valve, so I replaced it an Isuzu one and it has been fine ever since. He thermo-flap thing even works now.

 

[70 FJ40]

I very much agree with you guys about de-smoging. I think it helps the 2F a lot to get rid of all that extra stuff, but only if its done correctly. I'm not a mechanic, so I'm just trying to get the truck to run well at this point. It seems like it doing good for the most part, but ya I think I have it dialed in and then something will happen or yesterday it smelled like it was running really rich.

I'd really like to find a thread with definitive instructions on the way to desmog that has pictures or a map of how things should be. Mostly I've just found lots of different opinions and I'm not sure who is right. I'm not mechanicly savvy enough to figure it out on my own. I suppose if I had enough time, I could. Work and kids, though, you know.

 

[70 FJ40]

I likely have the parts I need to do it correctly because I have most of the smog equipment from a couple of 2F motors I bought that were getting motor swaps. Just dont really know what or how.

 

[CruiserTrash]

I very much agree with you guys about de-smoging. I think it helps the 2F a lot to get rid of all that extra stuff, but only if its done correctly. I'm not a mechanic, so I'm just trying to get the truck to run well at this point. It seems like it doing good for the most part, but ya I think I have it dialed in and then something will happen or yesterday it smelled like it was running really rich.

I'd really like to find a thread with definitive instructions on the way to desmog that has pictures or a map of how things should be. Mostly I've just found lots of different opinions and I'm not sure who is right. I'm not mechanicly savvy enough to figure it out on my own. I suppose if I had enough time, I could. Work and kids, though, you know.

I think finding threads on desmogging is helpful, but ultimately fully understanding what all the systems do, how they interact with each other and the basic combustion process, and what your goal is (what "desmog" means to you) is the solution. Study that Emissions FSM. You got this!

@Spike Strip Isuzu valve??? I need details. After sitting at a stoplight in hot weather, the truck is super rich from accumulated fuel and gets a little weird trying to take off when the light turns green. I've always guessed this was due to the inop HIC (hot idle compensator - it's right there in the name). It did this on my old 2F and my new rebuilt one. Here in Denver I'd love for the HAI to actually work during the winter too. You're right though, Toyota was asking a lot of that little valve.

Interestingly I've had another problem since owning this truck. During cold starts below about 45 degrees (truck has to sit overnight or about ~8 hours), the engine misfires BAD for about 1-3 minutes, then the idle will very suddenly smooth out. It almost ramps up from the misfire to the smooth idle over about 5-10 seconds - you can watch the motor sort of come "online". During the misfire idle my AF gauge shows the motor running super rich with the choke completely off - which it has to be since the choke will kill the engine from making it even richer. So I have to sit with my foot on the throttle. Once the motor "wakes up" I can take my foot off and pull the choke. Happened on the old 2F and the new one. I'm wondering if that has anything to do with the valve in question. Seems unlikely, but I've chased so many dead ends trying to solve this.

 

[Spike Strip]

I posted in your other thread about that Isuzu valve LINK I used the aftermarket version. It doesn't have to be that particular sensor, any of the GM type with two nipples will work fine, too - that's what BTB uses when they 'restore' a later Air Cleaner. There's a pic in that thread. Those GM type valves are all over ebay as NOS. They all function essentially the same: when cold, vacuum is directed to thermo-flap thing to uptake pre-heated air, then when hot, bi-metal spring gradually opens to bleed filtered air into carb. In the FJ60, it's through the PCV system.

I think you're right, too, about so many trucks running around with that thermo-flap stuck in the closed position because every one of those HIC valves I've tested always fail to the default of vacuum to the flap, so it's always 'up'.

I only went with the Isuzu valve because it's made in Japan and was readily available on RockAuto, at the time, reboxed as various brands. I don't see it anymore Looks like it has been discontinued.

Your cold-start issue seems more like one of the BVSVs is not working correctly (you still have all the smog equipment, yes?) but who knows. Could be at that temp (not something we normally see here ) without the air cleaner flap working, you're not getting proper fuel vaporization. It's also common for modern gasoline to 'capillary' out the venturi tubes overnight and pool on the bottom of the intake. Modern gas has a much-lower surface tension than gas from 40 years ago.

But all I can add is a LOT of the idle issues I was having went away when I fixed that HIC and thermo-flap on the air cleaner.

 

[CruiserTrash]

I posted in your other thread about that Isuzu valve LINK I used the aftermarket version. It doesn't have to be that particular sensor, any of the GM type with two nipples will work fine, too - that's what BTB uses when they 'restore' a later Air Cleaner. There's a pic in that thread. Those GM type valves are all over ebay as NOS. They all function essentially the same: when cold, vacuum is directed to thermo-flap thing to uptake pre-heated air, then when hot, bi-metal spring gradually opens to bleed filtered air into carb. In the FJ60, it's through the PCV system.

I think you're right, too, about so many trucks running around with that thermo-flap stuck in the closed position because every one of those HIC valves I've tested always fail to the default of vacuum to the flap, so it's always 'up'.

I only went with the Isuzu valve because it's made in Japan and was readily available on RockAuto, at the time, reboxed as various brands. I don't see it anymore Looks like it has been discontinued.

Your cold-start issue seems more like one of the BVSVs is not working correctly (you still have all the smog equipment, yes?) but who knows. Could be at that temp (not something we normally see here ) without the air cleaner flap working, you're not getting proper fuel vaporization. It's also common for modern gasoline to 'capillary' out the venturi tubes overnight and pool on the bottom of the intake. Modern gas has a much-lower surface tension than gas from 40 years ago.

But all I can add is a LOT of the idle issues I was having went away when I fixed that HIC and thermo-flap on the air cleaner.

My carb bowl 100% does drain into the intake overnight. Sometimes even 5 minutes after shut down, like if I'm running into the grocery store. Two carbs in a row have done that on me. Thanks for the reminder on the valve - I had forgotten we talked about that!