Timing not advancing

[Familyguy78]

What am I doing wrong if I have a functioning vacuum advance but I get no change in timing with any of its vacuum lines removed? Does this mean I have the hoses hooked to the wrong locations on the carb?

[dlb]

What am I doing wrong if I have a functioning vacuum advance but I get no change in timing with any of its vacuum lines removed? Does this mean I have the hoses hooked to the wrong locations on the carb?

Lol you beat me to it. I just answered this in your other post. Yup my guess is that you have some vacuum lines mixed up. The upper port with the big hole on the vac advance should be connected to manifold vacuum. If the underside of your hood has the emissions sticker, it will make it clear how to connect them.

[Familyguy78]

That label is blank, I'm going off the 1986 fed diagram posted here. I'll take a shot at the vacuum lines soon! Thank you dlb!

[dlb]

No sweat FG. That's good, the federal diagram here should work.

I find it hard to follow the metal lines that the vac hoses attach to so what I do to simplify the routing procedure is disconnect the hose at its start and end points, then blow through it. If I can feel air coming out the other end, I know I've got both ends right.

[Familyguy78]

Hey there we go that should speed this up! Great idea!! Thank you times 2 dlb!

[Familyguy78]

Ok, found 2 vacuum leaks! One port on the choke breaker does not hold vacuum, and the rear upper port on the vacuum advance has a slow leak. All vacuum lines are routed correctly. I noticed only 2 ports on the advance move the metal arm under the rotor, the third port which I believe is the high altitude compensator does not move the arm, is this right? Also, the vacuum modulator has no label on it, I do not know which port is which on it. Any advice?

[dlb]

Nice work!

For the choke breaker, just disconnect and plug the hose that goes to it until you can replace it. The carb will run a bit rich without it, it will be interesting to see how much it affects fuel economy.

The two upper ports on the vac advance share the same diaphragm so disconnect and plug both hoses that go to those. One of those ports (the one for the high altitude compensator) just has a tiny hole which is probably why it appeared to not move the arm. I think it takes a long sustained vacuum to affect it.

thumbnail_IMG_0343.jpg

Here's the emission sticker from my car. I imagine all the EGR vacuum modulators are the same so it should work for you. Looks like Q is the port at the front of the car, P is the rear passenger side one, and R is the rear driver side one.

[Familyguy78]

Good lord that is a simple emission set up! My vacuum modulator has one port pointing forward and one pointing backwards, not counting the larger hose going down to the egr valve. What would happen if I were to switch the modulator 180 degrees (switch it's vacuum lines?) I will also cap off the choke breaker and 2 upper ports for the vacuum advance. I'm hoping this will allow the timing to advance at idle, it's been stuck at 5 degrees btdc and the only thing that changes it is turning the distributor.

[dlb]

Yeah, I like the emissions systems on the manual trans Canadian al25's. Very simple, no annoying EBCV like the US cars have. Our automatics have it but I don't like the auto's anyway.

I didn't realize some vacuum modulators had only two ports. But now that I think about it, I think that if you take a really close look at it you might see tiny embossed letters at each port to indicate which is which so maybe try that. I think I remember that from long ago. I have no idea about reversing the modulator, I don't think I would do that though.

Unfortunately, because the upper advance diaphragm is broken, the only way you can get the timing to advance at idle would be to swap the hose with manifold vacuum (the one that is normally for the upper port) to the lower port. This will advance the timing more than it is supposed to at idle but not by much, and it will also advance the timing at hwy cruising, so this is probably the best you can do for now. Just make sure to plug the ported vacuum hose that usually goes to the lower port if you go that route.

[Familyguy78]

What does the ecbv do, and how is it tested? Now that I think of it, I'm not sure any vacuum is at any of the hoses going to the distributor while running. I got something to plug vacuum lines, I'll try again tonight or tomorrow evening. Thank you again for all your help!

[dlb]

I'm not sure about the EBCV because I only had the one car with it (I just fixed it up for a friend, didn't spend much time with it) but if you look in the emission section of the factory service manual it goes into detail about what it does and how to check it.

viewtopic.php?t=8103

[Familyguy78]

The link doesn't work. I can't find the fsm. Maybe I'm just running on 4 hrs sleep and slow

[dlb]

Weird, I just tried it now and it works for me. I'll try it again.

viewtopic.php?t=8103

Still the short version. Maybe try putting

https://tercel4wd.com/forums/

at the start of that link?

[Familyguy78]

Super weird, now it works ha ha thank you dlb!
I just now saw the post about Tom, I'm so sorry, you guys knew him well, we have lost one of our best

[Familyguy78]

Ok I found the Q port mark under the vacuum modulators cap, but I noticed the modulator was dripping black liquid from the hose that goes to the EGR valve! I've capped the leaks and am not getting vacuum to any of the hoses going to the distributor.