b 2000 running rich 1987

[bansh96]

i have gave it tune up.acts like it is fouling plugs after 100 miles idles rough.took off converter exaust thinking it was plugged but wasnt.does the same thing runs.even took air filter out to see if it would lean out did a little but not enough thanks for the help.later

[Brent Lamontagne]

inside the carb there is an idle solenoid that pulses and keeps your engine idling by releasing mini squirts of fuel several times a second. Mine got stuck open and i had terrible gas mileage but i had it replaced before i got 25 miles on it so I never had fouled plugs.
Could be your problem.

[89B2200]

On the pass side of the carb, there is an idle mixture needle valve that is behind the roll pin lock.
It is the bottom hole.
While reading the O2 sensor output with a digital meter set to DCvolts,
you adjust the idle mixture screw until the O2 sensor output crosses 0.5 volts as many times as possible. Do this on a fully warmed up engine.
If you are reading below 0.5 volts, you have a lean idle mixture.
If you are reading above 0.5 volts, you have a rich mixture.
You want a reading that crosses 0.5 volts, meaning you will get say 0.2 - 0.8 volts range that's always jumping up and down and crossing 0.5 volts.
When the engine is cold, O2 sensor does not work, so measure on a warmed up engine.
O2 sensors on B2200 is a single wire with no heating unlike on 3 wire sensors.
When engine is cold, rich idle mixture is possible only with a good working electric choke.

Hope that helps.