My Bronco (90XLT 5.8L) is blowing black smoke at acceleration (dumping fuel). Does anyone know what the problem could be?

 

Try replacing your oxygen sensor

 

You may also check to make sure your air and pcv filters are clean and unobstructed, for starters..... Are you getting any sort of error codes (check engine / emissions light on?). I agree, change your O2 sensor if it never has been switched out. From here, I'd make sure the engine was in good tune (plugs, wires, cap, rotor, etc.) and proceed from there...... Could be any one or a number of things - weak ignition coil (or module?), MAP sensor going bad, coolant temperature sensor going bad and unnecessarily richening (is that a word?) the mixture..... If you're getting codes, that will help to narrow things down. Otherwise, you may save some $$$ if you own a multimeter and are able to test some of the sensors, if the tune-up is not the issue. Good luck!

 

 

Definetly sounds like 02 sensor. But if youve allready checked that, is there any chance that you are running too high PSI in your fuel pump? Also, did you get a performance chip? If you did, they tend to make the engine run richer usually because it thinks you are running mods.

 

Pull the vacuum line off of the fuel pressure regulator and look for fuel (or fuel smell) in the line. The FPR will leak, letting fuel into the intake and causing a rich condition.

Probably also a good time for plugs/o2/etc once you get the problem sorted out.