I noticed the last couple times i've started my truck it has stumbled and black smoke puffed out the exhaust. When revving the engine black smoke poured out. After the motor got warm it pretty much seemed to get back to normal, but when floored it would still let out a puff of black. Does this sound like an O2 sensor getting lazy?

 

Tye ,
could be alot of different issues causing that . you need to check the codes to be sure what is causing it . and yes the o2 sensor will be telling the ecm it is running rich and throwing a code . but that doesnt mean the o2 sensor is bad .

 

It could be a bad 02 sensor. How old is the one in there? Could also be a bad fuel pressure regulator. As McG said, check the codes. When mine went bad, the 02 sensor was WAAAAY out of range.

 

The truck has 59,000 on it, original O2 sensor i'm pretty sure. i bought it with 39,000 on it. How can i check the codes?

 

Scooter, if you go to your local Wal-Mart they sell scanners so yuo can run a test and find out what codes you get (comes with a chart that says what the codes mean also). It sound like just what my dad's Econoline 150 did before. It would stumble at idle and black smoke would come out. I figured it was a clogged fuel line and I was 100% correct. To fix the clogged line I took some vise grips and put them on the fuel line near the carb, I then started the van up and revved it and let the remaining gas in the line run out. Then when the van was about to stall I released the tension in the vise-grips and I had my dad floor the throttle and the sudden burst of gas flow cleaned the line out and the motor has went back to normal weith good idle and no black smoke at all. If this is your problem then you won't get a code from the scanner.

Good luck Scoot...

 

to bad that isnt the case here . as he has multiport fuel injection and there is no rubber fuel lines in the system . and carbed engines symptoms are totally different then EFI ones . get the chiltons ford truck repair manual #26664 and a scanner .

 

Opps your absolutly right Macgyver. Sorry I forgot all about the EFI!

Scoot I would still get the scanner tho.

 

Your truck MAY be one that is affected by the recall on the fuel pressure regulators. I know mine is, I just haven't made time to take it in. Like they said, check your codes, see if they confirm your running rich. If you are, its likely to be O2 sensor, TPS and/or Fuel Pressure Regulator. If it is running rick fix it quick because that can cause you to ruin your catalytic convertors (expensive) and/or wash too much oil off the cylinder walls and create excessive blowly..