[updated:LAST EDITED ON 09-May-02 AT 08:42 AM (EST)]Hi,

My brother has an '81 Ford Auto I6, (used to be mine) and it has had a tough time passing emissions this year (Colorado).

I looks like where it's failing is the CO at 2500 RPM. It's too high. A shop tried leaning the mixture, but it was still too high. I bought that carb as a reman a few months ago. The shop said that it may be leaking fuel into the chamber, causing the mixture to be rich. So, I got another carb and put it on and they will adjust it for me. I also put on new spark plugs.

This is what else we've done to it:
Oil Change
Air Filter
Breather Filter
Fuel Filter

I was reading that a O2 sensor could be the cause of this problem. Does this truck have one? I've looked at several auto part sites and they list one for it. Is this true? If so, how does it control the mixture. The only electrical wire (that I remember) that goes to the carb is the Choke assist.

Also, anyone try the stuff you get at parts store that supposedly helps you pass emissions? Something like fuel system cleaner. Do they work?

Thanks in advance,
JazzBass

 

I do not beleive there is an O2 sensor on carburated engines. I may be wrong but, what good would it do? It cannot control anything.

 

He's correct, there's no 02 sensor in non-injected motors that old. I'd bet the motor is just old. If its not blow by past the rings, then maybe the valve stem seals are worn.

 

My 85 had an O2 sensor before I got rid of all that feedback carb BS. Too much CO or CO2? If too much CO, then that soinds like it is running lean. I'll have to reseach my hunch a little but I read about it somewhere.

 

Thanks for all the responses.

>My 85 had an O2 sensor before I got rid of all that feedback
>carb BS. Too much CO or CO2? If too much CO, then that
>soinds like it is running lean. I'll have to reseach my
>hunch a little but I read about it somewhere.

How do I know if I have a feedback carb? Where was the 02 sensor located? I've read that it's in the exhaust manifold. I've looked there already, but I did not see anything.

We're going in for the 4th and hopefully last test. This is what we've done to it up until now.

Reman Carb and shop adjusted
PVC Value
Spark Plugs
Oil Change
Air Filter
Breather Filter
Fuel Filter
Running Super Unlead and a bottle of Berryman's Emission Pass Protection.

Hopefully it will go.

Thanks again,
JazzBass

 

Different motors put the sensor(s) in different places, but in some of the Ford Trucks, its below the exhaust manifold but in front of the catalytic converter. Look for the wires coming out of your exhaust pipe.

 

Thanks Stephens.

I'll look for it.

I'll report result over the weekend.

JazzBass

 

84-86 had the feedback carb. Nothing before then had it, and the 87+ is EFI (though I heard something about 87 carb'd trucks, i've never seen one and know of noone that has either). You do not have a feedback carb on your truck.

Simple way to check if you don't belive me is to look at your motor. Feedback carb uses a computer and a boatload of wires going into the cab. On the drivers side in the hump in the firewall, is there a passthrough with 20-30 wires going through it? Are your sensors electric instead of mechanical (water temp is easiest to see). Do you have wires going to your ignition (TFI-IV) instead of a vacuum line (DII for your year). Etc etc etc.

In the 84-86 trucks, the O2 sensor is in the exhaust manifolds themselves. In the 87-96 the sensor is in the Y pipe off the factory duals.


-=Whittey=-