Keep getting code 42 on KOER test. Changed o-2 sensor. Shows always rich. on 1990 Ford Bronco

Trucks been non-op past 6 or so years. Tried inj. cleaner. Checked connectors. Generally seems to run o.k. but still sometimes gets a dirty inj. Don't have a emissions manual or breakout box. Any way to check o-2 sensor with ohm meter?

by in Foresthill, CA on October 13, 2013
3 answers 4 comments
ANSWER by on October 13, 2013
Think you have more problems then an o2 sensor. Leaky injectors/pressure regulator. Trying to remember, Warm up engine - test the gry/lt-blu wire and ground. Idle should be 0.1-0.9v, increase engine speed voltage should increase and decrease as rpms drop. If it doesn't work as stated it's probably bad.
COMMENT by on October 13, 2013
Thanks,I'll''give it a try.
ANSWER by on October 13, 2013
Full size Bronco? If so which engine?
COMMENT by on October 13, 2013
Yeah, I thought that info was there. It's a full size Bronco with a 4.9 L 6,5 speed former Forest service vehicle with 85,000 miles.
COMMENT by on October 13, 2013
Same injector giving the trouble every time? These engines had some connector problem at the injectors. Did you change the fuel filter? How much old gas is in the tank? Don't worry with the code just yet!
COMMENT by on October 13, 2013
Yeah. I changed the fuel filter and the #5 fuel inj. was dumping raw fuel but then cleaned up. I changed it anyway but didn't help.
ANSWER by on October 14, 2013
AGREE WITH #1