This thread is to try to determine the potential consequences of disconnecting the o2 sensor on a carbureted '82 pickup. I bought the truck this way.

The problem is that almost randomly (I have tried to keep track of the starting conditions each time), the truck will be hard to start or require starting fluid to be sprayed to start. When it needs starting fluid, I also need to stay on the gas pedal for an almost random amount of time. That is, sometimes a minute, sometimes 10 minutes, before the engine will idle on it's own.

I guess that the emissions computer on this truck, I hope, is not actually necessary to get it to run right, but I may be wrong. Even if I am wrong, I must note that the O2 sensor line has been cut, and there is an aftermarket Caralytic Converter in place of the original. But if folks have desmogged these trucks, they have done away with all the other systems associated with emissions, from cat to EGR valve, and all the other vacuum gear, which I still have.

I thought my carburetor may have been gummed up, so I bought a rebuild kit and cleaned the living heck out of the carburetor, which had been drawing in foreign dirt because it had no gasket at the air cleaner and had developed cracks as a result of vibration. I welded up the cracks and replaced the gasket, and rebuilt the carb. Still, the same problem persists: randomly hard to start from cold, requires throttle to maintain idle for a random period of time, once hot, most of the time isles steady, with the rare exception will do the same thing even when hot.

The main thing I'm suspecting, if the remanufactured carb yields no change, is either the temperature sensor which is a vacuum item, (at the area where the intake manifold passes coolant) or the fact that the o2 sensor has been cut, in which case I might need to obtain a factory catalytic converter and o2 sensor line.

If all these things fail to provide satisfactory results, I may need to resort to desmogging this truck to restore everything to basic engine chemistry. I would probably also first ensure that all fuel lines were clear and replace every inch of vacuum line and ensure that every vacuum component flowed as it should.

 

Well let me say I don't know much about the emission system on this truck but I know it can run fine without all of it, and I would recommend using a Weber which is much simpler, amongst other benefits. Are you sure you have no vacuum leaks that could seal up when the metal gets hot and expands?

 

I thought about the possibility of a vacuum leak that seals when hot, I have yet to check into it. I did find one hose a little split at the end when I took the carburetor out to rebuild it.

Now it's back to needing starting fluid on every cold start, so maybe one of the vacuum hoses I put back on was temporarily better sealed right after the rebuild. They did seem to seat pretty firmly but when I get the remanufactured carburetor, I will also be replacing all of the vacuum lines. I feel that the reman carb will prove if something is going on inside or outside the carburetor for sure- if I get the exact same symptoms, chances are the carburetor was fine the entire time, but if not, something I did not get to in there, whether it was an impossibly clogged small passageway, missing part from previous work, or some other small detail.

Maybe between now and getting the new reman carb I will replace vacuum lines to check that possibility.

The reason I asked about the o2 sensor is because there is one vacuum switch that is electrically controlled or monitored. I'm not sure how that plays in to the circuitry.

One reason I doubt the her sealing the vacuum leak is the seemingly random amount of time it takes to idle on it's own. After it reached that point fairly quickly today, it randomly stalled and became again hard to start right when the light turned green. That sucked. But maybe yes, something controlling the idle circuit gets better with heat. The temperature has been pretty consistent here lately, and the results being fairly inconsistent.

During times of hard start, I always look to find the float bowl plenty full of fuel, so I doubt any problems up the line from there, but have still been curious to test send and return fuel lines for openness. I would suspect that a clogged or partially clogged return line would overfill the bowl and come out the charcoal canister vent line- I haven't found that to be wet yet. If that were happening, I would think it would maybe cause some overly rich condition and maybe similar problem to what I'm having, but I don't think it's that based on what I've seen so far.