1994 GMC Safari service engine soon light

1994 GMC SAFARI
247,857 MILES • 6 CYL • 2WD • AUTOMATIC
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69 MALIBU
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  • 4 POSTS
the above light does NOT come on after the engine starts,but it runs real rough.i have changed plugs,wires,cap,rotor,fuel filter and rebuilt the tbi. when i spray throttle body cleaner in while engine is running it runs smooth.this tells me it is fuel related,correct? would a obcd 1 scanner do me any good,since the service engine light does not come on?also i replaced the fuel pump last year.
Sep 18, 2008 at 4:34 PM
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MERLIN2021
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If it runs this way all the time, hot or cold, it could be a vacuum leak, take that spray can of throttle body cleaner, and spray around the top of the engine at the manifold corners and the vac lines, if it smoothes out, you found the leak. If temperature related, test the ect.
Sep 18, 2008 at 4:56 PM