TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC 6 Cylinder Engine Repair and Modifications
  New Posts New Posts RSS Feed - Concord won't idle suddenly
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

Concord won't idle suddenly

 Post Reply Post Reply Page  <1234>
Author
Message
matty 401 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/06/2007
Location: Iowa
Status: Offline
Points: 1730
Post Options Post Options   Thanks (0) Thanks(0)   Quote matty 401 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/25/2018 at 3:05pm
glad to hear she is running smooth again 
72 matador 401 the beast
79 concord 2 door
72 matador 304 grasshopper
68 Rogue 406
93 Cherokee 4.0 5 speed

Back to Top
purple72Gremlin View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jul/01/2007
Location: Illinois
Status: Offline
Points: 16591
Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Aug/26/2018 at 1:55pm
Wont stay fixed. Cars dont fix themselves
Back to Top
FSJunkie View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jan/09/2011
Location: Flagstaff, AZ
Status: Offline
Points: 4741
Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Aug/26/2018 at 3:35pm
The fuel, vacuum, emissions, and computer control system on those engines looks really scary, but if you study the vacuum diagram and the service manual it's actually not that hard to understand. There is a lot of stuff, but you can sort it into individual systems. EGR system, CEC system, etc. and each individual system is actually really simple. There are just a lot of systems.

I went through all of it on my 1984 Eagle 258. Literally rebuilt the entire engine and went through everything under the hood in the process. The computer controlled 258's actually run extremely well when everything is working as it was designed. I cannot believe how well it runs. 
1955 Packard
1966 Marlin
1972 Wagoneer
1973 Ambassador
1977 Hornet
1982 Concord D/L
1984 Eagle Limited
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19608
Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Sep/05/2018 at 6:24am
My rule for cars with lots of vacuum controls is to replace all the vacuum lines when you start having troubles and they all look like they've been in there a while. I bet you still have most of the original hoses! They get hard with age and under-hood heat, and they can lose the seal on the components. Many times new hoses (or if long enough trimming a bit off the stretched end) will bring everything back. If you have to trim a hose like that I'd replace it soon after -- it's still an old hose. ANY vacuum leak will affect running. You got lucky this time -- I'd replace all the others, and still check that the intake/exhaust manifold bolts are tight.
Frank Swygert
Back to Top
maximus7001 View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Jun/27/2011
Location: Winnipeg,Canada
Status: Offline
Points: 1080
Post Options Post Options   Thanks (0) Thanks(0)   Quote maximus7001 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/10/2018 at 5:48am
X2 on changing all the vacuum hoses.
1968 Javelin SST

1997 GMC Safari AWD

2001 Daewoo Nubira SX (Winnipeg only model)

1997 Honda Accord EX (Canadian Model)

Winnipeg, home of the Jets.
Back to Top
tomj View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jan/27/2010
Location: earth
Status: Offline
Points: 7522
Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Sep/11/2018 at 11:02pm
X2 or X4 on replacing ALL HOSES, period. even or especialyl ones that look good. if they;re from 1978 they are not good.

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

Back to Top
Fahques View Drop Down
AMC Apprentice
AMC Apprentice
Avatar

Joined: Jan/06/2016
Location: philadelphia
Status: Offline
Points: 49
Post Options Post Options   Thanks (0) Thanks(0)   Quote Fahques Quote  Post ReplyReply Direct Link To This Post Posted: Sep/12/2018 at 8:18pm
Sage advice. It ran ok for a few days and then back to stalling. I've been looking at the chilton and it doesn't seem too out of controll to replace all the hoses. I've been reading about all the emission parts and their functions, it's starting to actually make sense. A little bit.

I also started reading about the 4.0 fuel injection swaps. That's way out of my league. I can't really say I understand that just yet but I'll keep reading up on it until something clicks. I would like to keep the car and keep it as close to stock as possible. Seems a rarity that many amc' stay stock.

Thanks for all the advice, I'll check back after the weekend to post the outcome of the hose changes and if I found anything weird with the manifold or other gaskets.
Back to Top
tomj View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jan/27/2010
Location: earth
Status: Offline
Points: 7522
Post Options Post Options   Thanks (1) Thanks(1)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Sep/12/2018 at 10:33pm
there's no substitute for the factory service manual. haynes and chilton are too generic. there's model-specific junk in there that will drive you nuts. the factory manuals are a great buy, check out abebooks.com. best money you can spend on your car is a service manual.
1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

Back to Top
maximus7001 View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Jun/27/2011
Location: Winnipeg,Canada
Status: Offline
Points: 1080
Post Options Post Options   Thanks (0) Thanks(0)   Quote maximus7001 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/12/2018 at 11:17pm
I have had 2 of these cars/trucks with the carter bbd carbs. 18 years of these carbs. The first one was a 81 Concord DL, daily driver year round here in Winnipeg. The idle tubes plug up in these carbs. I rebuilt the carb both times and problem solved. Gotta get ALL the passages completely clean with an air hose and a piece of tie wire after soaking, first time I missed some.

Second one 1985 Eagle wagon (truck in Canada)(no cat or smog pump). Also daily driver year round. You can on purpose cross cyl 1 and 6 on the cap then start it up and rev it repeatedly. It will backfire out the carb and "probably" blast out the idle tubes from the bottom. It worked every time for years on this truck. This does usually work well in it is not plugged solid and is safe for the engine and the carter bbd carb. Do not do this with motocraft carbs or any other carbs with a power valve.

After many times the backfire method did not work anymore so the carb had to come apart. They are real easy to rebuild.

One other thing. The return fuel hose coming from the filter (smaller hose) has a check valve inside of it. If you ever change that line you need to keep that check valve and record the direction orientation of it. Push it inside the new hose with a screwdriver. If it goes missing the car will never run again. Make sure that return line is at the top (12 o clock position on the filter).

Change the filter regularly, they are cheap.


Edited by maximus7001 - Sep/12/2018 at 11:22pm
1968 Javelin SST

1997 GMC Safari AWD

2001 Daewoo Nubira SX (Winnipeg only model)

1997 Honda Accord EX (Canadian Model)

Winnipeg, home of the Jets.
Back to Top
farna View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar
Moderator Lost Dealership Project

Joined: Jul/08/2007
Location: South Carolina
Status: Offline
Points: 19608
Post Options Post Options   Thanks (1) Thanks(1)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Sep/13/2018 at 9:49am
That return line fuel filter and check valve bite a lot of people! Understanding the emissions and how everyting works together is the key to keeping an emissions Eagle running as it should. You can get most of the CTOs (the vacuum switches that screw into the block) now. They are the same thread and temps as many GM cars, it's a GM computer system IIRC. The stepper motors can freeze on the electronic BBD, but it's usually sensors or CTOs that stop working.

Many people take all the emission controls off and set the electronic BBD in a mid-way position (look up "Nutter bypass"). That works reasonably well, but it won't have the power and mileage of a car with a perfectly functioning emissions system. It just runs a lot better than one with a broken down emissions system, so it's seen as an improvement.  If you really want to ditch the emissions get a good non-feedback carb AND distributor. The electronic distributor isn't really curved right to run without the computer, though it will function. An aftermarket carb like a Weber 32/36 and aftermarket HEI distributor or an older Motorcraft distributor (or even older Delco) is really needed. Then tune both to the engine. The next step would be a better cam. An Isky 256 Supercam makes a great street car upgrade, a bit more power without losing fuel mileage (and better mileage in some cases). Comp 260H would be my second choice for a mild improvement. You can get a bigger cam, but for a daily driver one of those will be very good.
Frank Swygert
Back to Top
 Post Reply Post Reply Page  <1234>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.234 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or