rebuilt 4.9 will not idle with vacuum line connected

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05-23-2021, 05:19 PM

steve100

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rebuilt 4.9 will not idle with vacuum line connected

We have a rebuilt 4.9 carb motor that will not idle with the vacuum line hooked to the brake booster attached . could the carb be the problem? I will be grateful for any suggestions. Thanks

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05-24-2021, 10:58 AM

SFaulken

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Generally that indicates that the check valve or diaphragm in the Brake Booster is shot.

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05-24-2021, 01:24 PM

cstephens

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Could also indicate that you have the throttle blades or choke closed too far and the engine is struggling to idle when you take away a source of air that it is actively using.

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05-25-2021, 07:24 AM

steve100

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Thank you both. I an thinking carb be cause it runs like a charm when you pull the vacuum line from the booster and it sucks in more air. thanks again

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