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post #1 of (permalink) Old 09-15-2003, 11:11 PM Thread Starter
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disabling stepper motor on carter BBD

I have a Carter BBD with a stepper motor. I want to rebuild it to put on my 258. I won't be using the computer controls of course. Once the stepper motor is unplugged does it have any effects on the carb other than just looking stupid? I don't understand much about how it works so I thought there might be something else I have to do for the carb to run well without it. perhaps unbolt it from the carb body and make an access plate to go over the hole?

I want to get my CJ running again with a low budget and keep the emissions so that they look stock, that is why I'm not swapping a MC2100 on (yet).

thanks [img]images/graemlins/laugh.gif[/img]
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post #2 of (permalink) Old 09-16-2003, 02:35 AM
 
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Re: disabling stepper motor on carter BBD

don't unbolt it... the air/fuel mix needles are connected to it, if you yank those out your vehicle will run poorly, if at all. You'll want to move the needles into the "full rich" position before disabling them. It's part of the nutter bypass.
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post #3 of (permalink) Old 09-16-2003, 09:50 AM
 
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Re: disabling stepper motor on carter BBD

To disable it, simply unplug the electrical connector, and it will remain it it's current position. If it was on the jeep and idling, and it was idling ok, I would unplug it then. After that, all adjustments to mixture are by the two screws on the front of the carb base.

I had no problem with this, but you could run into a problem if the stepper motor was stopped in an extreme position that prevented adjustment to a good idle mixture via the screws.
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post #4 of (permalink) Old 09-16-2003, 12:28 PM Thread Starter
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Re: disabling stepper motor on carter BBD

Thanks for the replies. Unfortunately, I got this carb on a Jeep awhile back and it was already unplugged. So I don't know if someone unplugged it when it was idling or the previous owner could have tinkered with it. I see the 'pin' sticking out of the stepper motor. Is there a way I can set it manually? In what position should it be set? thanks
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post #5 of (permalink) Old 09-16-2003, 12:54 PM
 
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Re: disabling stepper motor on carter BBD

if you're going to set it in a position manually, set it in full rich (all the way out of the motor, towards the radiator.) You can do that by removing the motor and pulling them gently, or an easier way would be to do it with the harness connected, but that assumes that your computer still works.
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post #6 of (permalink) Old 09-16-2003, 01:01 PM Thread Starter
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Re: disabling stepper motor on carter BBD

I have to pass a tailpipe sniffer test at idle so full rich might ruin my chances for that.. I'll play around with the settings, thanks
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post #7 of (permalink) Old 09-16-2003, 01:09 PM
 
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Re: disabling stepper motor on carter BBD

This could be an oversimplification, but within a reasonable range of settings of the stepper, the idle mixture screws on the front will make up for it's setting. Ie, if it's set lean on the stepper, the screws on the front will simply be set richer (further out). If it's set rich on the stepper, the mixture screws will simply be set further in. Use a vacuum gauge to set the two screws for the leanest peak vacuum reading (manifold vacuum).
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