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1990 GMC S15 Question: My truck is a 1987 4cyl and when i turn the key on the throttle body fills up.

 

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BC-S-15, 2.5L 4 Cylinder, Sparta, TN, January 19, 2014, 15:39
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When i turn the key on the throttle body fills up

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  • Answer #1

    January 19, 2014, 15:45
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     Master

    Leaking injector o-ring seals. Most likely! Unplug injector wire connector to see if it still does it. Post the test results for more info.

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  • Answer #2

    cardocIII from Gillespie's Auto Service, January 19, 2014, 17:47
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     Master

    A defective ignition module was a common cause for this. They would falsely send a very fast pulse on the ref wire to the PCM even without the engine cranking.

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