Carter BBD issues

For what it's worth I see a few things wrong with the line routing...

First off, double check the lines to the fender-mount vac switches.  The rear one should run to a delay valve and a small reservoir, then to the distributor.  It looks like it may run directly to manifold source.

In the photo below, the vacuum source for the air cleaner switches and flaps is the one on the corner of the carb base.  I believe you have red and blue reversed at the carb.  The tubes marked in green are for the Pulse Air system.  If pulse air has been removed, leaving these unplugged will allow the carb to pull in un-filtered air (if I remember right).




In the next photo, the port circled in red is fed from the HVAC controls.  This blocks coolant flow to the heater core when AC is selected.  It may not be needed, but make sure the hose isn't a leak point.



In regards to the "Sol-Vac" on the front of the carb and idle speed:  This is enabled under two conditions.  The electric (solenoid) portion is extended when either the headlights, rear defrost or AC is switched on to bump up idle speed for the extra load.  The white plastic side, which should have a vacuum nipple underneath, is enabled by a electric vacuum switch on the valve cover.  This is enabled by the computer when needed.  It will also kick up the idle during a pre-timed amount under hot and cold starts.

So, without any electrical intervention, these are at rest and the idle should be adjusted with the curb idle screw.  The TSM details methods for setting idle when both the vacuum and electric sides of the Sol-Vac are enabled.

80/81 were different indeed.  I should have mentioned that.  Without the TSM it's really a guessing game.  At least the firewall decal is present.  That would indicate exactly what his car requires.  On my '86 the idle is adjusted by a screw that rides on the end of the Sol-Vac plunger.  You are correct.  I was remembering it wrong.

Since it has been established that the car is an 83 model yet it is clear that it no longer has the original feedback carb, it could be related to the computer still being half "in the loop" and not being able to correct A/F ratio, thus manipulating other switches in some kind of limp mode.  Driving around with the computer in open loop may not be the most efficient thing to do and could cause some major driving problems.  There was a year in which the computer began controlling ignition timing as well.  My '82 Eagle lacks that but my '86 Eagle has it.

This is a very hard problem to troubleshoot without being in front of the car.  Whoever owned it has placed it somewhere between factory and "keep it running".  Generally I like to keep things stock, but it isn't beginner stuff, so I've found.  You need a lot of spare parts that are NLA and it's almost best to start from scratch with all new lines following that firewall diagram.  You would also need the correct carb for your application (a BBD feedback with stepper motor).  You will also need a true AMC TSM and a good understanding of each component in the system.  There is a great website that will help explain what each part does:

http://home.sprynet.com/~dale02/

Back behind the carb, there should be a square connector hanging loose with I believe 6-8 leads.  This would power the stepper motor on the original carb.  This motor controlled the air/fuel ratio, which the computer would monitor via the o2 sensor.  When the car starts, either warm or cold, the computer enters "open loop" mode (there are a bunch of open loop modes depending on coolant temp, intake air temp, etc).  When the right conditions are met (normal operating temp, warm intake air, startup timer complete, etc), Closed Loop is entered.  With your current setup, you'll never get to that state, so the car will run (most likely) in one of the various open loop states.

How to fix it... learn it and piece it back together, or bypass the computer (continue what the PO already started).  There are many guides to doing an ECM "test bypass".  Sounds like it's mostly all there to make stock, but you will need a feedback carb at the very least.

As a closet 6 cylinder fan here in Phoenix I have the 80 nailed. I actually know of no one who actually drives a 6 cylinder AMC vehicle and the 80AMX in the drive way and my Spirit at the only ones I know of regularly driven and participating as hobby cars. The AMX is a 3rd owner car and as it turned out had many modifications to the smog system, my Spirit when purchased was blown up and junk. Both cars were restored to exactly letter perfect correct and it took a long time to find the missing components searching through Pick A Part cars. My Spirit has since be modified for fuel injection, but the MOPAR supplied unit and is still smog legal. The engine for the car when 1980 OEM correct was running compression and a cam and dyno'ed 110 Hp at the rear wheels. When smog legal they would run correctly and very well and I have yet to see one correct over time. It is way too hard to put them back together correctly due to lack of parts. I have not bothered trying to purchase a newer 6 cylinder AMC car due to lack of interest in part with Eagles and the sad shape they are found in.
I can't help on this one. As pointed out there were numerous changes as AMC used smarter and smarter computers to get the cars to run and time has not dealt with them very well.
An 80? I have all the data to make them run well. Newer ones? I can bypass what is there to get them to run well. I don't like the plastic valve cover and no one I know owns one.
Sorry. I'd like to help, but can't

So. Interesting.

I switched the carburetor choke hose to the plugged one and hooked up the air cleaner. Surprising development, the car worked perfectly. So I made the mistake of turning it off.

Now it's exhibiting the same symptoms as before.

Can anyone tell me what could possibly be happening with a car that runs perfectly until you turn it off and then back on? Because that seems to be a common theme here.

Also, unrelated, I went ahead and replaced the PCV grommets. The connectors were so loose you could take them out with a stiff breath.

I should probably mention that every time it stalls, the engine rumbles to a stop, like it's being slowly strangled. It doesn't just straight up and die.

Edited by Tarnish - Oct/13/2016 at 4:47pm