94 bravada running rich

i just bought a 94 bravada and it is running very very rich all the spark plugs are black and it shakes at idle like it has a miss i have checked for vacuum leaks i dont have any i checked firing order it is correct i replaced the coolant temp sensor because it had the truck thinking it was -40 degrees all the time my friend found out that was bad with is scan tool i am about to replace the 02 sensor does anyone have any ideas what this could be

i just bought a 94 bravada and it is running very very rich all the spark plugs are black and it shakes at idle like it has a miss i have checked for vacuum leaks i dont have any i checked firing order it is correct i replaced the coolant temp sensor because it had the truck thinking it was -40 degrees all the time my friend found out that was bad with is scan tool i am about to replace the 02 sensor does anyone have any ideas what this could be The egr valve on both the blazer and the bravada are known for going bad. If it is indead stuck the check engine light would be on. They can however get stuck half open and will cause the car to run rich or lean. I am having a similar problem and was told to take the egr valve off, spray it out with carb cleaner, get the plunger moving back and forth a few times and then put it all back together again. It sounds like you are having a similar problem. I replaced the o2 sensor and it was a waste of $50. Good luck

Sounds like your Central Point fuel Injector(CPI) is leaking from the injector unit and the fuel supply line is possibly cracked. On the scan, did you get a Trouble Code 45, O2 sensor sensing rich condition?
That kinda narrows it down to the fuel leaks inside the intake manifold...it happens on all CPI motors sooner or later. I did my '92 about 7 or 8 years ago and I'll get to do it again in a few years. Don't wait too long about fixing it because the raw fuel spray can get past the piston rings and thin your oil out bad enough to destroy the motor...I hate to be so blunt but it's already happened to some other Bravada owners. I have some instructions, if you need'em I'll post'em.

i am not getting any trouble codes at all that is what is getting me all plugs are black i changed o2 sensor still does the same thing i took the top off the plenum i didnt see anything leaking it was dry i am starting to think that the injector is stuck open all the time now i have to check wiring to see if it is grounding out somewhere keeping it open have u guys heard of anything like that happening if so whick wire would ground the injector

The inside of the intake should be greasy, terrible looking. Very clean areas near the CPI or fuel lines indicate fuel leakage. What about the air filter?

i just replaced my fuel pressure regulator on my cpi unit and my truck still runs the same and my lines arent leaking what could be the problem it still runs rough and i still get black smoke out of the tailpipe i found out that motormite sells the fuel pressure reg for 92-95 cpi units part number is 55162 i want to know what else could the problem be

Maybe a coupla long shots,
On the map sensor, jumper the light green and the purple wires. You should get 1 to 1.5 volts at idle.

You should be getting a trouble code 45-O2 sensor sensing rich condition.
There's also a mention of a loose gas cap.

so when i jump the wires on the map sensor do i leave it plugged up to the sensor and where do i measure voltage from and when i do this test the check engine light should come on correct? and what is the deal with the gas cap that will make the truck run rich too it is a obd 1 car

I use small safety pins tc access the wires with a digital volt/ohm meter while plugged in the the sensor and the keyswitch on.

The '92 Factory Service Manual I have is where I'm getting info from as it's been useful on most 91-94 Bravada problems. It made mention of the loose gas cap.

i went to check the gas cap it wasnt loose but it wasnt gm either it was a nissan cap would that have anything to do with it does the factory cap pressurize the system to keep the engine from running rich

The factory seals the fuel system so the fumes go to a charcoal tank at the front of the car and are drawn into the motor under certain conditions. I don't see where it's ability to vent or not will blacken the spark plugs.
If the plugs are black due to a fuel injection problem that has been corrected, they might not still be firing right because of being gasoline fouled...it's another long shot but you might try installing new spark plugs. Here's a trick...change the plugs through the rubber flap at the inner fenders behind the front tires...it's a straight in shot at the plugs with a wobble joint and a 12" extension. Be very careful around #5 plug (rear plug/drivers side) as there's a knock sensor that has a very fragile plastic connector that'll break if you touch it and the engine will run like junk if you loose that connection.
Is there smoke coming out of the exhaust pipe and if so, what color?