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1990 Chevy truck failed ignition timing and vacuum line disconnected

I have a 1990 Chevy truck. I took it to a test only center and it failed. The said the timing was not set correctly and that 25mph test for HC (PPM) was too high 112 where the max is 110. When I got home from the smog check station I looked under the hood disconnected and noticed that the vacuum line that comes off of the carb. intake base plate to the recovery canister was disconnected. Also there was no evidence that they disconnected the blk/tan wire which is required to determine the correct timing. A friend of mine said the disconnected vacuum line would cause it to fail. Is this true? Is the smog shop committing fraud?
Answer:

The disconnected vacuum line would probably cause a high idle and cause ignition timing to get off mark. Timing has to be checked with the vehicle at a specific idle (usually indicated on the Emissions Inspection label), and if equipped, the Timing Inspection Bypass wire disconnected (at times bypassed- grounded). It will be hard to determine at this point whether the technician did in fact disconnect or bypass your vehicle's bypass wire. Your vehicle should have failed the visual test for the disconnected vacuum line. I recommend replacing the vacuum line and having the smog station inspect the timing again. Hopefully your vehicle was tested at a Test Only smog station which offers a free re-test. posted by SmogTips Support

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