Missing vacuum line or plug?

no

on the left, you see the "differential pressure" switch

one line of the corresponding electrovalve goes to the intake
the second line goes to the "cut off" valve ... and the third to atmosphere


and you are sure that every little thingy of this system works like it should ?

 

It is unclear from your photo if all of your air injection system vacuum tubing is plumbed as is shown on Table 9.

Table 9 shows two vacuum hoses coming off of the solenoid (Part #2), which likely means the solenoid is switching between vacuum/no-vacuum to Part #1 (Cut-off Valve). If so, this means that "no-vacuum" would require a vacuum connector open to the atmosphere as your photo shows and Michael has already confirmed. Confirm you have two vacuum hoses connected to the solenoid.

These solenoids can be used to switch vacuum to two different locations, but it doesn't look like your car is using that solenoid that way.

Its a little mysterious what Part #18 does.

 

Part #18 (the differential pressure switch) is not part of the air injection system -- it just gets the intake manifold vacuum signal from the same hose and is mounted on the same bracket.

 

Probably not, but - when you say this: "Start the car and idle speed by tach is a little over 1000rpm. Rev engine to 3500 and lift off throttle. Engine then drops below 500rpm and recovers but just barely. On the road it will stall under braking." -- does it have the same symptom during both cold-running (Lambda system not active) and warm-running (Lambda system active), or only during one or the other?

 

Not quite following you on the sequence of events (so please edit/correct what's below to be more exact about the sequence of events):

1. Car was running fine, both cold and warm with the O2 sensor signal plugged in.
2. Car started having the problem only when warm, but cold was OK (O2 sensor still plugged in).
3. Unplugged the O2 sensor, then both cold and warm were OK again.
4. Now both cold and warm have the problem (O2 sensor still unplugged).

Also, is your frequency valve "buzzing"/vibrating when the engine is running?

 

I mentioned this to you before that the fuel clicking off or "upchucking" is common with QV and 328. Since you still seem to think you have a filling problem here are a couple of quotes from other threads.

 

I still don't think that is the source of your problem since the fuel pump draws fuel from the D side tank. The crossover pipe being clogged would only affect your range. But here is a quick test. Driving straight, with the gage reading 1/2 full, what happens when you go around a turn, left or right? You should see the gage move towards full for one direction and towards empty when you turn the other way. Not talking about a left or right turn, but a longer sweeper on a highway like I 95, at highway speed. If you see the gage move like that it is an indication that the fuel is moving between tanks. In my car I can latterly go for low fuel indicator on to over 1/2 tank deepening on which way the road curves.

Other option is that you gage is off, reading 1/2 when you are only down a 1/4 (or less).

 

Sorry to hear that. I know you have had a lot of problems with the car. Seems odd. My 85 has been bullet prof since new. I guess that's the benefit of a one owner car that has never been fooled with. You'll figure it out.

 

It does only tell driver's side level as that is where the float sensor is but the level in both tanks when stopped on level ground is the same unless the lower crossover or possibly upper cross-vent is clogged. I had trouble fueling my car when I first got it until replacing the filler and crossover hoses. Now I can pump in full blast with no problems.

 

The crossover hose between tanks or something like 1" 5/16 ID.
Sorry guys, just have a really hard time believing that plugged off inless you're shoving rags down into the fuel tank.

 

A tank will not fill from the bottom if there is not vent at the top to let the air escape that the liquid is displacing.

Since you've recently replaced the two pup hoses on the crossover pipe, it is unlikely the problem is there. It is more likely that the vent pipes at the top of the passenger tank have been plugged. There are 5 of them. Why they plug and unplug sporadically is a little mysterious.

 

I’ve had the top crossover pipe clog on a semi. It would run out of fuel unexpectedly from draining one tank first. By the time someone got there with fuel, it would restart (before adding that fuel) after a very slow transfer from the other tank. It was presumably also leaving me stranded because of the slow transfer at filling. I was leaving the yard with less fuel than I thought (or that it showed) that I was carrying.

A little condensation build up and any tiny bit of bio-film can have a hay day in the lines.

 

Excellent! Glad to hear you've found the prime suspect.

Note though too, that there is a larger hose/pipe shown as #62 "Breather Pipe" on TAV 11: Fuel Pumps and Pipes. That pipe splits at the driver side tank with one branch going to the driver's side tank and the other branch going high on the fuel filler neck.

It looks to me like the purpose of this pipe is to 1. allow rapid venting of vapors while the tanks are being filled and 2. general pressure equalization between the two tanks as the level drops from fuel being consumed.

As long as this "Breather Pipe" is open, all the other 4 top ports on the passenger fuel tank could be plugged and the passenger tank could fill as quickly as you want.

 

yub, line 22 should not leak -
otherwise, when ever the engine pulls vaccum, like under breaking, unmetered air would be drawn into the plenum ... engine stalls

for a first test, you can take line 22 off the plenum at juntion 24 and close that hole (line 22 will leak to atmosphere during the test)
sure, you could just tape line 22 - but maybe it is also perforated else where ...
report back what you find


the canister valving construction lets the gas tank pass excess pressure (with gas vapors) out through the charcoal bed to atmosphere
whenever no engine vacuum is present, but the pressure in the tank builds -
it draws air through the charcoal bed (to "dry" it) when engine vacuum is present.