Can anyone point me in the right direction? I failed the emmisions test here in colorado twice. Both times I was over the limit on high CO. I have an 84 Bronco 300. Thank you.

 

High CO Emissions
Excessively rich air/fuel mixture

O2 sensor malfunction

Faulty computer control(s)

Malfunctioning fuel injection system

Inoperative/missing catalytic converter

Carburetor float level maladjusted

Air cleaner, choke or carburetor
Air injection system failure

Defective canister purge system

 

Whanes is right. It could be any or a lot of things. Check his post from yesterday regarding emissions testing. I failed the Colo test (once or twice) with a 150 - 200K (high mileage) motor and brought it back to within specs with a good basic tuneup - oil/filter, air filter, pcv, points, plugs, wires cap & rotor. High HC suggests a rich mix. What do you have - carb or EFI? If stock carb, leaner is OUT with the mixture screw. Try 1/4 turn (engine warm) at a time out and listen to see if the engine "smooths" and rpms increase. If (after)1 full turn (1/4 at a time - 15 secs in between) you don't see an improvement, turn it back( one full turn) in and check elsewhere This is best set with a vacuum but can be improved by ear. The carb may need "going through".

'Been to the COLORADO club forum?

 

http://www.aircarecolorado.com/repair/fixit.htm

The Ford 300 1983-1985 with the feedback carb is in their list of problems.
http://www.aircarecolorado.com/repair/ford.htm

Larry

 

that is an interesting article LHO39 seeing as show I could never get my 85 4.9L to pass with the stock intake, exhaust and carb. I did just get it to pass with an Offy DP intake, Cliffy single outlet header, Holey 390 and a new exhaust here in Colo Spgs, CO.

Check out this thread:

http://www.ford-trucks.com/forums/sh...hreadid=108486

for some info and a few pics are located here:

www.codegrunts.com/~jsampsel/ol_blue.html

I also replaced the O2 sensor, plugs, wires and had the timing and carb adjusted.

 

I just got my 84 F150 through after it failed due to high CO after checking everything and eliminating two vacumm leaks including the EGR bellows, I replaced the O2 sensor and made a fuel air ratio meter, you can buy these already to install from JCW and Jegs and some performance shops, But I'm cheap and made my own. I tried adjusting the idle but it was never ideal and then I adjusted jet rod through the hole in the top of the carb you have to use a #9 torx driver, clockwise for rich counterclock for lean. Be carefull not to unscrew it all the way or you will have to open up the top of the carb to put it back together. I warmed it up good and drove it down the road, I kept adjusting it leaner and leaner until then A/F indicator showed the mix to be fairly reasonable I would monitor it ad 35MPH on flat ground as this is the max speed they test on the Dyno in Arizona. The day I went in for the second test I stopped just down the road from the station gave it about another turn and a half lean and kept the engine hot. it passed. I've got two years to replace the old feedback carb and all of the other crap.
good luck

 

Thanks for the ideas guys.

As far as the smog pump (air injection?) goes it works and the valves that turn on the air to exhaust and cat work but the computer is not turning them on. I hooked a straight vacuum to the valves and can get the air to pump to the cat. It seems like there is no signal from computer or something to turn these valves on. I did run engine at 2000rpms and verified that none of the vacuum lines coming from those 3 solenoid switches by the firewall is turning on (1.airpump to exhaust 2.airpump to cat 3.EGR). If I pull the ends of these three vacuum lines there is no vacuum and any rpm. I do have a good vacuum to those 3 solenoid switches so I'm guessing the problem is electrical or computer related. Anybody know when these vacuum lines are activated? I believe the air to the cat helps to lower emmisions and I think the air to the exhaust port is just for preventing backfire? Could I cheat the system and just hook a straight vacuum to get the air from smog pump to always pump air to the cat?

I never like the feedback carb thing and this is what the emmisions people said "This pickup/Bronco application typically suffers from abuse, neglected service and a poorly designed manifold and feedback system."

The thing is the truck is running rock steady and has lot's of power with no misses (probably because there is no computer or feedback action to mess with it).

I don't really want to pump any money into this thing and I know if I take it to one of the approved emmisions repair shops I will get hosed. This truck is my daily driver and nothing else (it's a rustbucket). I just need it to pass this time I dont think I will have it in 2 years.

CO limit is 55 and I tested at 65.

Sorry for the long post..Im at my wits end.. 84 Bronco 300

 

I've learned more than I need to know about these damn things thats why i'm going to aftermarket and retrofit manifolds and injection. If none of them work check your temparature sensors, If I remember right none of them work until the engine reaches temperature, at least that was the case on a friends van. Also I don't think they work until the engine reaches a certain RPM. One of the pain in the butt things about feedback units is they have a computer but no diagnostics, so you have to check them one by one, Oh and I forgot if the O2 sensor is bad these thing will not work right either.
I had so much trouble with the systems rotted, broken, missrouted etc. that I disabled the feedback features on the carb so it is simply a carb then I blocked off the EGR and ended up with only the thermactor (air) pump working and I installed a heated EGO to replace the one wire unit, I just wired it up the same as on the later 88 F250. I did all of this so as I worked on getting the CO level down I didn'd get any interference from malfunctioning feedback systems. The A/F mix still bounces around but I'm told thats as good as a carb gets you just have to look at the operating average, I know it passed emissions with plenty of room to spare the second time around and it looks like it has all of its emissions and since it passed I didn't bother reenabling the stuff I disabled. I also have an old courier that has a shell of a catalytic and no other operational emissions systems at all, and when I tune it up and throw on a new air filter it passes. Obviously well tuned engines will pass but poorly tuned and malfunctioning sytems will not despite emissions controls.
Get a torx driver set the folding ones work well they have long reaches, use I believe the number #9 and adjust the metering rod through the hole in the top of the carb you can see the adjustment if you look down in there with a light. counterclock (out) is lean and clockwise (in) is rich. Adjust it like one half or one turn at a time with the engine hot and drive it accelerating smooth and gradual and keep leaning it until it starts to stumble a little when you accelerate then just tweak it rich a little until it barely stops stumbling that may get you through since you are so close.