A couple days ago, I changed out my upstream O2 sensor (with a Denso, if that matters), fouled catalytic converter and muffler since the previous owner had a straight pipe. On my way home from the muffler shop, after the new O2 sensor, I still left a grayish cloud that didn't appear to be caused by oil or coolant when I took off from stops. Today, I tackled a couple leaky fuel injectors and got them taken care of, since I figured they were the cause.

Problem is, my wife, who was under the hood to check for any leaks when I started the Jeep, saw there was a new leak on a different injector. So I think I'll just replace the O-rings on all the other injectors. Long story short, that brief couple minutes that it ran left a nice, sooty spot on my driveway. Is there a good chance it's simply due to a leaky injector? FYI, it appears my fuel pressure regulator is okay.

Thanks in advance, guys.

Edit: It is a '90 Cherokee 4.0

 

i had this same problem with my 98 it was blowing black soot out of the tailpipe i had a bad fuel injector i bought some upgrade fuel injectors and reset the computer and it was good. since your gonna change the orings for the fuel injectors anyway you should go check out the for sale section for some upgrade ones from programbo.

 

How do you know the regulator is OK? Did you check the pressure?

 

I didn't check the pressure. It's probably not 100% guaranteed, but I had read, and been told, that if the vacuum hose attached to it has fuel in it, you can assume the diaphragm inside is ruptured. My vacuum hose was clean, so I figured it was all right.

 

Better check the pressure