I have a 99 Chevy blazer with the 4.3l V6. It has been running very poorly for awhile now. I put a new Coil, distributor, sparkplugs, and wires. I have put new 02 sensors as well. The only thing I have not changed is the spider injector. I misses like crazy and drinks the gas. I estimated the gas mileage to about 11mpg. I have a giant black spot in my drive way where i start it up of a morning. If I floor it black smoke bellows out. I have also put a new cat in but that has been about 4 years ago. I opened up the intake and I have posted a picture to show what it looks like. There is clean spot on the 3 cylinder. All three spark plugs black soot over in a short period of time. I check the spider leads and cannot see any pin holes. If anyone has any ideas that would be appreciated. Just wanted to make sure that it was the spider injector causing my problems, before I bought one.

 

pretty good bet your leaking - plug the spider in with the plenem off - do koeo test and watch for leaks