HELLO EVERYONE I'M NEW TO THE FORUMS. I HAVE JUST ACCQUIREDAN 88 4.3L T.B.I. IT WAS RUNNING GOOD FOR 100MILES AND THEN IT STARTED CHUGGING AND BLOWING OUT BLACK SMOKE. THE MOTOR NEVER STALLED BUT IT HAD NO POWER. HAD TO HAVE IT TOWED HOME. MY QUESTION IS WHAT IS THE MOST PROBABLE CAUSE OF THIS? I WANT TO TRY AND SAVE SOME MONEY AND FIX IT MYSELF. IM PRETTY MECHANICAL BUT MY DIAGNOSIS IS NO GOOD. WHAT TESTS COULD I PERFORM TO CONFIRM WHAT IT MAY BE? I CHANGED FUEL FILTER, PLUGS, ROTOR, CAP, WIRES, AIR FILTER....I DO NOT KNOW THE HISTORY OF THE VEHICLE THE CONVERTOR LOOKS PRETTY OLD THOUGH,.........THANKS FOR YOUR HELP!!!!(I HOPE) MARK

 

If it is blowing out black smoke then you are definitely running rich. pull the air cleaner off and inspect the injectors. if they are working properly they should be misting on the throttle plates if they are driping buy a repair kit and replace the screens on the injectors and buy some carb/injector spary and clean them out. If the injectors are working fine recheck the spark plugs to see if they are firing. what spark plugs did you buy anyway.