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Pacer with 258 won't idle - Newbie needs advice |
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PL36
AMC Fan Joined: Apr/12/2021 Location: San Antonio, TX Status: Offline Points: 7 |
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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!
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blumontag
AMC Addicted Joined: Mar/05/2013 Location: minneapolis Status: Offline Points: 834 |
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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.
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72 Gremlin X
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7522 |
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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. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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MIPS
AMC Nut Joined: Mar/11/2019 Location: Kamloops, BC Status: Offline Points: 346 |
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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.
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davec1957
AMC Nut Joined: Jul/09/2010 Location: Massachusetts Status: Offline Points: 385 |
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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 |
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1970 AMX Bayshore Blue 390 4-spd GoPac
1970 AMX Commodore Blue 390 4-spd GoPac |
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CR CRUISER
AMC Apprentice Joined: Aug/13/2007 Location: Canada Status: Offline Points: 166 |
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Stuck EGR valve? Pull the hose off of it and reach in with your fingers and pull the diaphragm. It should spring back.
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PL36
AMC Fan Joined: Apr/12/2021 Location: San Antonio, TX Status: Offline Points: 7 |
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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).
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PL36
AMC Fan Joined: Apr/12/2021 Location: San Antonio, TX Status: Offline Points: 7 |
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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.
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PL36
AMC Fan Joined: Apr/12/2021 Location: San Antonio, TX Status: Offline Points: 7 |
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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.
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7522 |
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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. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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