TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > AMC 6 Cylinder Engine Repair and Modifications
  New Posts New Posts RSS Feed - Pacer with 258 won't idle - Newbie needs advice
  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.

Pacer with 258 won't idle - Newbie needs advice

 Post Reply Post Reply Page  12>
Author
Message
PL36 View Drop Down
AMC Fan
AMC Fan
Avatar

Joined: Apr/12/2021
Location: San Antonio, TX
Status: Offline
Points: 7
Post Options Post Options   Thanks (0) Thanks(0)   Quote PL36 Quote  Post ReplyReply Direct Link To This Post Topic: Pacer with 258 won't idle - Newbie needs advice
    Posted: Apr/29/2021 at 8:32pm
Bought a nice, mostly original 1976 Pacer hatchback recently. It has the upgrade 258 single-valve engine and an automatic transmission. It probably sat for a while in storage before it came to me. It starts fine and runs surprisingly smooth when the accelerator is pressed, but will die quickly when idling. Gas does flow to the carb and I've driven around the neighborhood a bit, but the inability to idle has me stumped. So far I replaced the fuel filter, added fresh ethanol-free gas to a nearly empty tank and put in a bottle of octane boost and SeaFoam as well, sprayed the carb with cleaner and even replaced the Ignition Control Module which a friend suspected had caused his Pacer to stall out similarly. Any suggestions on what to try next? Feel free to explain like I barely know my way around under the hood. Thanks!
Back to Top
blumontag View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Mar/05/2013
Location: minneapolis
Status: Offline
Points: 834
Post Options Post Options   Thanks (1) Thanks(1)   Quote blumontag Quote  Post ReplyReply Direct Link To This Post Posted: Apr/29/2021 at 9:05pm
I'm no expert either, but if you've got good flow to the carb then perhaps the carb needs a good cleaning or even rebuild. Then, adjusting air/fuel mix at carb for best idle.
A tuneup with fresh plugs is always helpful for a car that's been sitting.
72 Gremlin X
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 (2) Thanks(2)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Apr/29/2021 at 11:49pm
You can go two routes here: goo full diagnostic, get the service manual (we call 'em TSM, Technical Service Manual, best money you'll ever spend on the car) adn go through all the tests and work it out. 

Or preemptively replace, for starters, the multitude of vacuum signal hoses and fuel lines and most things made of organic material and hope it "goes away". It might! But even if it doesn't, 45 year old hose is most definitely now or soon a problem.

You say it sat in storage a long time; I hope you have not run it on whatever gasoline was in the tank. If you did, dont again. It will ruin your engine in short order. It may have already. 

I don't mean to be discouraging, but you can't really proceed without working out how things work, under the hood. What's your experience level? Do you know other engines/cars? Basic mechanical stuff? 

Sice it runs OK otherwise you can probably assume its a subtle problem. Smog controls of 1976 are pretty primitive. 

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

Back to Top
MIPS View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Mar/11/2019
Location: Kamloops, BC
Status: Offline
Points: 346
Post Options Post Options   Thanks (1) Thanks(1)   Quote MIPS Quote  Post ReplyReply Direct Link To This Post Posted: Apr/30/2021 at 11:59pm
How quickly does it die after letting it idle and can you bring it back with a press of the pedal? I have seen a weak fuel pump cause low flow at idle speeds but I've also seen a stuck float cause the engine to flood out when the throttle was closed.
Back to Top
davec1957 View Drop Down
AMC Nut
AMC Nut
Avatar

Joined: Jul/09/2010
Location: Massachusetts
Status: Offline
Points: 385
Post Options Post Options   Thanks (1) Thanks(1)   Quote davec1957 Quote  Post ReplyReply Direct Link To This Post Posted: May/01/2021 at 7:06am
One easy thing to check that you haven't mentioned is the choke adjustment. This could easily cause the car to stall (unless you keep your foot on the accelerator pedal) when cold if the automatic choke isn't adjusted properly (i.e. air/fuel mixture too lean). Search for "automatic choke adjustment" or something similar on YouTube for a quick lesson, it's an easy adjustment. The choke should be almost closed when you first turn the key, then after a few minutes of warmup the choke will open for a leaner mixture. It sounds like the choke is open too much upon initial startup, and this would require you to keep your foot on the gas to keep it running until it warms up.

Edited by davec1957 - May/01/2021 at 7:14am
1970 AMX Bayshore Blue 390 4-spd GoPac
1970 AMX Commodore Blue 390 4-spd GoPac
Back to Top
CR CRUISER View Drop Down
AMC Apprentice
AMC Apprentice


Joined: Aug/13/2007
Location: Canada
Status: Offline
Points: 166
Post Options Post Options   Thanks (1) Thanks(1)   Quote CR CRUISER Quote  Post ReplyReply Direct Link To This Post Posted: May/01/2021 at 10:59am
Stuck EGR valve? Pull the hose off of it and reach in with your fingers and pull the diaphragm. It should spring back. 
Back to Top
PL36 View Drop Down
AMC Fan
AMC Fan
Avatar

Joined: Apr/12/2021
Location: San Antonio, TX
Status: Offline
Points: 7
Post Options Post Options   Thanks (0) Thanks(0)   Quote PL36 Quote  Post ReplyReply Direct Link To This Post Posted: May/02/2021 at 8:44pm
Hi Tom. I'm handy and have plenty of tools, but haven't worked in cars since I was a teen with my Dad (35 yrs ago). I bought a copy of the TSM so being directed toward appropriate sections is helpful. If the engine runs fine when the accelerator is engaged I'm not terribly worried that I'm headed for a catastrophic problem just yet. My guess is that its a fuel line (which I should be able to handle) or vacuum issue (which I am clueless about).
Back to Top
PL36 View Drop Down
AMC Fan
AMC Fan
Avatar

Joined: Apr/12/2021
Location: San Antonio, TX
Status: Offline
Points: 7
Post Options Post Options   Thanks (0) Thanks(0)   Quote PL36 Quote  Post ReplyReply Direct Link To This Post Posted: May/02/2021 at 8:48pm
Thanks Dave.  I'll look up the choke adjustment procedure in the TSM or chase it down on youtube.  It does idle high. But even when the engine is warmed up by being driven around the block for 10 mins, it will still stall out unless the accelerator is being engaged. 
Back to Top
PL36 View Drop Down
AMC Fan
AMC Fan
Avatar

Joined: Apr/12/2021
Location: San Antonio, TX
Status: Offline
Points: 7
Post Options Post Options   Thanks (0) Thanks(0)   Quote PL36 Quote  Post ReplyReply Direct Link To This Post Posted: May/02/2021 at 8:52pm
Thanks MIPS.  The engine will start up but the accelerator needs to be engaged or it will stall - even if its been driven around the block for 10 mins.  Once it starts to stall, it dies quickly and revving the engine doesn't always intervene. I've got gas flowing but perhaps its not steady or sufficient.
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: May/02/2021 at 11:58pm
Ahh. It might be simply that it runs OK when "cold", eg. the choke is on, but too lean to idle.

Once warmed up (10 minutes) it drives OK, but won't idle (run at minimum speed with foot off the pedal)? If so idle adjustment is the most basic of all tune up steps.

1) find the idle speed screw, aka idle stop screw. Stop as in stops it from closing all the way.

2) Find the idle mixture screw. Usually knurled, or something, with a spring under the head.


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

Back to Top
 Post Reply Post Reply Page  12>
  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 0.109 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