'94 K3500 4x4 rough start and poor MPG

[markf]

Gentlemen,
I have a 1994 4x4, 350, automatic, 95K miles, rack body dump. When first started in the morning, it does not matter whether it is cold or warm outside, the truck will start, however, when I push on the gas it hestitates and the engine will sputter. Once warmed up, the engine will go with no problem even when turned off and restarted an hour or so later. I have replaced the air filter and PVC valve and cleaned the throttle body. I will replace the gas filter shortly. Plugs, wires and distributor cap are new.

The wire from the oxygen sensor was cut by the previous owner. I also need to know where that plugs in.

Any other thoughts would be appreciated since I am only getting 6 MPG unloaded. Also, I did notice that the temperature gauge does not go beyond 120. I remember hearing about a device within the coolant system that feeds a signal to the computer that tells it to run rich or lean.

Your help is greatly appreciated.

Mark

[Fireplug]

Well 94 is OBD1 System and if the o2 wire is cut then the check engine light must be on.
The computer then will not know what the hell is going on and stay in open loop and run with a preset fuel and timing spcs. That means piss poor gas mileage untill the o2 is fixed you can replace every part on that engine and it will not help with the mileage. As per the temp your gauge could be wrong or the thermostat is stuck open or a low temp stat was installed. A k3500 in a big heavy truck dont expect a hugh jump in mileage when the o2 is fixed you will be lucky to get 10 0r 12 mpg.

[Rbraczyk]

The 02 sensor is critical to the operation of the truck. It gives feedback to your throttle body so that it does not dump too much fuel into the motor. Replace that and your ignition and MPG troubles should dissappear. Remember, not all things that are supposted to throw a code will throw it when it fails.

[markf]

Gentlemen,
Thank you for your responses. I will replace the O2 sensor. However, can you tell me where the O2 lead plugs in?
Thx.

[C2500]

Your best bet is to go to a used truck lot and find a year and model that matches your truck. I assume your truck only has one sensor. Later vehicles have 4 or more. My 1990 has a purple wire that goes to the O2 sensor. Good luck!
Harry

[LT1 Kayker]

The O2 lead? You say your wire is snipped, so is the wire still in there, or all taken out? The sensor itself is usually on the drivers side exhaust manifold or a little bit under it before the Y pipe, but on newer GM trucks they have like 4-8 of them in the cat, in the Y pipe, in the dashboard, in your seat... you get the point haha. The wire from the sensor usually goes into the computer dealy next to the primary coil deal thats right in front of the distributer. Thats the way it is on my truck at least.(89 C1500) I probably didnt help you at all but im bored so here I am. I get around 4mpg on my Lo3 305 4 speed auto so don't feel too bad haha.