Spark plugs STINK of fuel

The van I am having an issue with is an 1989 Chevrolet P-30 with a 350 under the hood. Cube Van

The van only has 20,000 original miles and was emission tested 5 monhts ago and passed in flying colours.

The van gets horrible fuel mileage (could be due a a cube van) and the exhaust is enough to kill you. I mean, any exhaust can kill you but this thing wreaks.

The van starts and runs excellent even in the -24 c weather we are having except for the horrible exhaust smell and the poor fuel mileage. I pulled the plugs today and they wreak of fuel. The look fine and I have changed many plugs in my life time and cannot say I get an over whelming fuel smell such as this?

What would cause the plugs to stink of fuel? Keep in mind the truck is Throttle Body Injected and is an older vehicle with low miles

If the thermostat is stuck open the temperature will be low and the computer will think it needs extra fuel because the engine isn't up to temperature.
A cracked manifolt around the oxygen sensor will put extra air around the sensor causing a rich mixture.
If you take a flashlight and look at the injector you can observe the extra fuel going to the engine.

It is funny that you metnion the thermostat. I have replcaed the thermostat not due to being stuck open or closed, just changed out the fluid and figured would put a new one in.

The Temperature sensor however has not been working since i purchased the vehicle and I even put a new sensor on and it still did not work. I think there is an issue somewhere in the wiring or the actual gauge itself as I get no reading. I put in an aftermarket gauge so I could get an accurate temperature reading and have the existing temperature gauge still hooked up but just sitting ontop of the block. I think this is where the problem may lye as the computer may be getting an inaccurate reading. If I disconnect the temperature gauge entirley the truck will not start so I am under the assumption the temperature sensor is still operating leading me to believe I have an issue with the factory gauge.

Truck runs and starts fine everyday except for the aweful fuel smell

You have one sensor for the computer system and another one for the gage.
Look at the parts store for the one for the computer system. I've also found them coated with scale. If you have a manual you can check the ohm readings on the sensor.
The sensor for the gage I would use a piece of no.14 solid copper wire about 4 to 6 inches long. Touch one end to the block and the other end to the wire. The gage should peg with somebody watching it and the ignition on. If it doesn't peg install a new gage if partially ohm the wire. I've found some parts store sending units don't work and installed a new dealer part and they worked. Feel both radiator hoses and make sure they are hot you may have a bad new thermostat. I heat up a old cup of water and imerse them to be certain they work before installing.

Just for an update.

I am out in this freaking -18 c weather checking for whats wrong on the truck. Anyway, i found the gauge sensor control wire on the block and for some reason it was disconnected. So, to sum things up, the coolant temperature sensor was disconnected by me 4 months ago to adapt a universal fit gauge for a reading of the truck.

After discovering the sensor control disconnected from the block, I have reinstalled the factory coolant temp sensor and re-installed the sesnor control and everything is working like it should.

Hopefully this will solve the issue of the truck running rich and have everything back to normal and the fuel mileage should get better.....

Thanks.....

Just for an update.

I am out in this freaking -18 c weather checking for whats wrong on the truck. Anyway, i found the gauge sensor control wire on the block and for some reason it was disconnected. So, to sum things up, the coolant temperature sensor was disconnected by me 4 months ago to adapt a universal fit gauge for a reading of the truck.

After discovering the sensor control disconnected from the block, I have reinstalled the factory coolant temp sensor and re-installed the sesnor control and everything is working like it should.

Hopefully this will solve the issue of the truck running rich and have everything back to normal and the fuel mileage should get better.....

Thanks.....

Be sure to change you oil and filter.
Gas may be in the oil from running rich.
Good luck