idling trouble- please help
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idling trouble- please help
i have a 1970 ford f100 pickup. my truck has been idling well since my dad and i adjusted the idle speed yesturday, but before it would cut off as soon as i let my foot off the gas. today its doing the same thing again. and yesturday it ran and drove great. i thought it might be my spark plugs and wires because the truck would be smoking too, but only on plugs 1-4. we played around with the adjustment screw but no matter what now, it keeps shutting off. what might be causing this and how can i fix it?
Lead Driver
Joined: Jan 2003
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From: Ohio
Welcome to FTE.
What motor? 302 or FE(390?) All stock? how many miles? Automatic transmission? What color smoke(blue, black, white?).
Do you have a tachometer to check rpm? Did you adjust the idle MIXTURE screws(in the front of carb)? First, bottom them out lightly, then turn them out 1 1/2 turns. Start truck and then slowly adjust them in till rpm just starts to fall off. Then back out 1/4 turn. Now adjust the idle. Idle has to be low enough for mixture screws to work, so make sure it's not over 700-800 rpm. Make sure the choke is properly adjusted also, make sure it's not falling closed, as this will make it stall also.
Fixing problems over the internet is kinda hard, but with some ideas you can at least do some checking. Hopefully you can get going in the right direction and get it fixed.
What motor? 302 or FE(390?) All stock? how many miles? Automatic transmission? What color smoke(blue, black, white?).
Do you have a tachometer to check rpm? Did you adjust the idle MIXTURE screws(in the front of carb)? First, bottom them out lightly, then turn them out 1 1/2 turns. Start truck and then slowly adjust them in till rpm just starts to fall off. Then back out 1/4 turn. Now adjust the idle. Idle has to be low enough for mixture screws to work, so make sure it's not over 700-800 rpm. Make sure the choke is properly adjusted also, make sure it's not falling closed, as this will make it stall also.
Fixing problems over the internet is kinda hard, but with some ideas you can at least do some checking. Hopefully you can get going in the right direction and get it fixed.
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i have a 302 engine. all stock. about 140,000 miles and its automatic. color is green. no i dont have a tachometer to check the rpm but i plan on getting one. no i didnt adjust the idle mixture screws i dont believe. im just goin to check everything this weekend, and do what you suggested. i think that might help, because i know its something minor. thanks.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
The Tach isn't critical, but helps especially with adjusting idle mixture(if you don't have a vacuum gauge to use).
The idea is to set the idle mixture screws for highest vacuum(rpm), then adjust your idle to correct idle rpm. The mixture screws are kinda hard to get to on an Autolite, but they are under the front bowl. Like mentioned, start about 1 1/2 turns out from bottomed out(lightly) and then slowly rotate one at a time to reach max rpm(listen carefully to engine). Then reset your idle speed.
Gauges help, but if you are careful and listen you can get it close enough if it's that far outta whack.
Color? I was referring to the color of the SMOKE out of the tailpipe. That will determine what is wrong with it. Black is "too rich", blue is oil, white is steam(possible antifreeze leak-head gasket/intake gasket problem).
The idea is to set the idle mixture screws for highest vacuum(rpm), then adjust your idle to correct idle rpm. The mixture screws are kinda hard to get to on an Autolite, but they are under the front bowl. Like mentioned, start about 1 1/2 turns out from bottomed out(lightly) and then slowly rotate one at a time to reach max rpm(listen carefully to engine). Then reset your idle speed.
Gauges help, but if you are careful and listen you can get it close enough if it's that far outta whack.
Color? I was referring to the color of the SMOKE out of the tailpipe. That will determine what is wrong with it. Black is "too rich", blue is oil, white is steam(possible antifreeze leak-head gasket/intake gasket problem).
