3.1L engine questions

I'm new to the 3.1L GM engine, but need some help

in the 1990 Grand Prix, the engine runs rich when warm. It is not all the time, but it will die out when accelerating sometimes. I installed new plugs, wires, oil, fuel cleaner, air filter, etc today but it still does it. I did notice the Oxegen sensor was disconnected on the rear exhaust manifold, but have no idea where it connects. After the engine stalls out it is tough to get it to restart again, and when it does start it blows out black smoke. The 1990 has 183,000 miles on it.

On a different vehicle, a 1992 Grand Prix, the car ran good, but this past week one day it was started and allowed to idle and died after about 10-15 minutes. 2 days later i went and started it again, and noticed the temp light was on when i started it. the temp gauge read cold at the time, then the gauge slowly went up as the car sat. I thoguht the temp light was for low coolant so I drove the car up tot he huse to fill it with water, but in the 2 minutes it took to drive it up there, the temp needle got to the red and as it was idling the engine shut down again. The next day it restarted and was able to be drivin back down to the barn, where it sat and idled and died again. Now it is tough to start. It turns over slow and won;t run. I think it needs a t-stat and/or waterpump. No heat came out of the interior vents or got to the radiator during this.
the 1992 only has 79,000 miles on it and has been sitting for several years. Do you think the engine is shot or are they pretty resiliant to overheating?

Thanks for any help!

I would start with checking fuel pressure, I had similiar symptoms on my 90gpse and it was a bad fuel pressure regulator causing the rich fuel condition(black smoke).
As far as how 3.1 's handle overheating ,I havent gotten mine that hot(knock on wood) yet.But it tried, today it got up around 220 before fans came on .I would try bleeding air out of system.
Its not much but I hope it helps.Let me know what you find out.
Peace

I'm new to the 3.1L GM engine, but need some help

in the 1990 Grand Prix, the engine runs rich when warm. It is not all the time, but it will die out when accelerating sometimes. I installed new plugs, wires, oil, fuel cleaner, air filter, etc today but it still does it. I did notice the Oxegen sensor was disconnected on the rear exhaust manifold, but have no idea where it connects. After the engine stalls out it is tough to get it to restart again, and when it does start it blows out black smoke. The 1990 has 183,000 miles on it.



On a different vehicle, a 1992 Grand Prix, the car ran good, but this past week one day it was started and allowed to idle and died after about 10-15 minutes. 2 days later i went and started it again, and noticed the temp light was on when i started it. the temp gauge read cold at the time, then the gauge slowly went up as the car sat. I thoguht the temp light was for low coolant so I drove the car up tot he huse to fill it with water, but in the 2 minutes it took to drive it up there, the temp needle got to the red and as it was idling the engine shut down again. The next day it restarted and was able to be drivin back down to the barn, where it sat and idled and died again. Now it is tough to start. It turns over slow and won;t run. I think it needs a t-stat and/or waterpump. No heat came out of the interior vents or got to the radiator during this.
the 1992 only has 79,000 miles on it and has been sitting for several years. Do you think the engine is shot or are they pretty resiliant to overheating?

Thanks for any help!

I'm sure its possible w/ the O2 sensor being d/c it will run rich, is the check engine light on? The compter is maybe thinking it needs more gas and is dumping it in there. vehicles usually do run rich on a cold start so it makes sense that when it is warm it would die.
The one that overheated, i would check the thermostat and see if it stuck closed. pull it out and put it in a pot on the stove and turn it on and as the water gets hot it should open up. if it stuck closed, you probably wouldnt have heat out the vents cuz the antifreeze isn't able to go through the heater core to give u your heat. also a plugged heater core will do that to. a water pump will usually leak if its bad but you would still get water through your motor until it all leaked out.

i have a 94 gpse and mine was overheating but mine was bacause of my voltage distributor was wazzed and sending too many volts to the comp and giving it false readings. the fans werent coming on a mine got to 220-230 ish then it just died wouldnt start but its all fixed now $150 later......

On the rich issue, find the plug for that O2, the computer reads O2 sensor voltage to help decide fuel injector pulse width, the higher the voltage the O2 puts out, the richer the computer thinks the engine is running, and vise versa

so, with the O2 sensor un-pluged, the computer sees no voltage at the O2 sensor. Idealy the computer should see this as a failure, set a code and run in "Failure mode." but being that it is a 90' it might just think that the motor is running lean, and thus dumping in all the fuel that it can, causing your black smoke and engine dieing (flooding)

For the 92' try running the motor with the radiator cap off to let the air work its way out of the cooling system, air in the system could cause the irradic engine temp readings. Those cars are notorius for having air in the cooling system

I agree with the other posters on the 90 model. Until you get that o2 hooked up, there's nothing else we can do to help, as the ECM uses o2 sensor signal to adjust fuel trim.
On the 92 that has sat, the t-sat is the 1st thing you need to change, as it is probably rusted shut from the car sitting. Let us know how it works out.

isnt there a blled screw on the top of the therm. housing that can be opend to bleed? my 2.8 had it just for that reason, to bleed the air out.