I'm working on a 1993 1500 4x4 with a 350 engine. it idles great and throttle responce is excellent. the problem is when you press the accelerator it spews out an excessive amount of fuel smoke out the exhaust. Seems to be running way to rich. Thought it might be the o2 sensor but its not pulling a check engine light. Any thoughts would be greatly appreciated before I start thowing money at it guessing.

 

I don't know much about your specific truck....but a general rule is that "black smoke" indicates a situation where your fuel/air ratio is too rich.

 

What color is the smoke?

 

Black, smells really rich. Its rich enough that when my friend pulls it into his garage it sets of his carbon monoxide detector in the house. it started doing this about a month ago, then he noticed his fuel mileage went to crap too

 

Your system needs a handful of sensors to ALL work and work well in order to control the efficiency and reliability of your engine. The way the "basic" OBD1 system works is Air comes in through the filter passes through mass air flow sensor or in your case a M.A.P. ( manifold absolute pressure ) sensor. This sensor is located usually in one of two places. 1) is on the fire wall on the left side ( facing engine ) or 2) on the manifold in between the valve cover and the Throttle body. from there it goes to the combustion chamber. After burning, it goes to the exhaust. At this point "samples" are taken from the A.I.R. system or smog control-Thank you
California- this in conjunction with the O2 sensors and the catalytic converter ( this expensive part super heats the exhaust gases to ensure the TOTAL burn of any unburnt fuel from the combustion chambers ) that tell the engine whether the fuel burn is either too rich or to lean and this will adjust your air/fuel mixture accordingly. Now not all of these sensors will show a "trouble" code. I think only the MAP/MAS sensors show an actual code ( of these few sensors ). There are some other sensors also, one is in the Filter box I think this one is barometric pressure. There is an I.A.C. ( idol air control ) valve this one is on the throttle body-cant remember what this on does- Of course the T.P.S. ( throttle position sensor ) blah blah etc. etc.

 

thank you all for the input, I'll start checking those sensors

 

black smoke indicates 1 of 2 things:
either your engine is about to give out or you are running really rich.
Sounds to me like it's running rich.
I'd replace the sensors, and also maybe replace the injectors.
good luck