Vacuum problem?
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Vacuum problem?
I've got an 83 F150, 4x4, with a 302 and a C6 and I'mhaving a heck of a time getting the idle right. It idles fine in park and neutral, but when I put it in gear it wants to die. I've got to keep the park/neutral idle up in order to keep it running when it's in gear and I often have to throw it in neutral when I'm coming to a stop light so it doesn't die on me.
It sounds like a vacuum problem, but for the life of me I can only find one vacuum port on the transmission. Shouldn't there be two of them? Anyone got an idea of where the second one might be? Or maybe I'm completely jacked up and you've got another idea?
I'd appreciate any help.
It sounds like a vacuum problem, but for the life of me I can only find one vacuum port on the transmission. Shouldn't there be two of them? Anyone got an idea of where the second one might be? Or maybe I'm completely jacked up and you've got another idea?
I'd appreciate any help.
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I've tried all manner of settings with the screws. In and out. Should they be more out than in? Are there any other adjustments that I'm missing? I've got a pretty basic engine w/o all the emissions/egr/other worthless junk on it. Just a factory 2 bbl carb and factory intake.
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when you screw the mixture screws in and out does it change the idle? and how are you adjusting them....?
also when it's sitting there idleing put a rag over the carb and cup it with your hand, see if the idle goes up or down... if it goes up than back down you are cupping it to hard, back off a little... if it idles right up good then you have an intake leak somewhere if it just dies than you might be too rich.....
also looking at where the throttle plates are in relation to the mixing slots inside the throats...they will tell you a lot...the plates should be med way I think, if yours are closeing the slots off to vacuum there is a leak somewhere.....
also when it's sitting there idleing put a rag over the carb and cup it with your hand, see if the idle goes up or down... if it goes up than back down you are cupping it to hard, back off a little... if it idles right up good then you have an intake leak somewhere if it just dies than you might be too rich.....
also looking at where the throttle plates are in relation to the mixing slots inside the throats...they will tell you a lot...the plates should be med way I think, if yours are closeing the slots off to vacuum there is a leak somewhere.....
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I've never noticed a difference when I've adjusted the screws, but I know it does idle a little slower when I put the air cleaner on. Right now I've got it set to idle about right when it's in gear, but it's idling way too fast when it's in park or neutral. I've never tried the rag trick, but I could give it a whirl.
Admiteddly, I'm no genuis when it comes to adjusting carbs, so that could very well be my problem.
Admiteddly, I'm no genuis when it comes to adjusting carbs, so that could very well be my problem.
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when you adjust the mixture screws turn them in until the engine starts to stutter...then back them out until the engine smoothes out, do one screw at a time, you may have to go back and forth a few times to get it balanced, bring the idle back down and do it again,. Then I like to back them out 1/8 of a turn and leave it.
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I can try it, but I don't know that it'll work. I've had it idling freat in park before, but as soon as I put it in gear it goes down to about nothing and often dies. I really just need to spend a day under the hood I think. Been spending too much time overhauling my mustang these past few weekends...
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Ok, the screws are all the way in now and it's better, but it still wants to die when I come up to a stop sign. It didn't really sound like the idle changes too much. I think I may have to take the carb off and check my gaskets to see if I've got a leak somewhere else.
What I really need to do is junk the 2 bbl set up and get me a 4 bbl set up...
What I really need to do is junk the 2 bbl set up and get me a 4 bbl set up...
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did you try the rag trick?..... if you screwed them all the way in it sounds like it might be rich....the rag trick will tell you that......also pull the carb and look at the slots see where the plate are.....
also is the timing set.
also is the timing set.
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I didn't use the rag, but I cupped it with my hands. The idle went up and stayed up. If I cut off all the air it died, but if I let a little through it just idled fast.
With the carb on the plates looked like they were right where they need to be, but I'll have to get a closer look when I pull it.
I haven't used a timing light, but the timing feels pretty good to me. It fires as soon as I turn the key and it runs smooth going down the road. I don't think that's the problem.
With the carb on the plates looked like they were right where they need to be, but I'll have to get a closer look when I pull it.
I haven't used a timing light, but the timing feels pretty good to me. It fires as soon as I turn the key and it runs smooth going down the road. I don't think that's the problem.
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ok now we are getting somewhere..... if the idle went up when you cupped the carb you have a lean condition. So either you have a vacuum leak or it's running lean.... Get a timing light.....
check for vacuum leaks......
check the egr if it has one.....
pull the carb and clean it......
check for vacuum leaks......
check the egr if it has one.....
pull the carb and clean it......
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The carb is clean. I rebuilt it in February. It's had the problems since before then. I bought a can of starting fluid last night so I'll check it for leaks. After tinkering with it for a while my hunch is a leak in the egr plate. I needed the height so I left it in there, but I blocked it off. However, I had to make a gasket to fit it so that might be my problem.
Please explain to me what you mean when you say it's running lean or rich. I know what that means in a chainsaw, but I'm a little unclear with a truck.
Thanks again.
Please explain to me what you mean when you say it's running lean or rich. I know what that means in a chainsaw, but I'm a little unclear with a truck.
Thanks again.