I purchased this truck about a month ago and plan to make it a weekly driver and an occasional camping/hunting truck. I repainted the exterior in a camo pattern and installed new carpet.

The only issues with the truck is that it idles rough and blows a little smoke out the tail pipe (black smoke).

I've been adjusting the carb and it seems to help a bit, but I think I need to continue adjusting it to get it just right. As for the smoke, it is still coming out, including some dark soot from time to time.

Now I have a few more questions...

1. I pulled codes from the truck... 18, 41, and 63. Not sure exactly how to proceed in fixing the problems.

2. What are these hoses and where do they go? I've included pictures for reference...

The first picture shows an inlet of some sort right in front of and below the carb.


The second picture shows what appears to be an exhaust tube of some sort but leads nowhere. It stops right above the frame.


The third picture shows an unknown item with a mounting bracket, hanging just under the compressor and carburetor. It appears to be attached to the tube above and another tube going nowhere.


The last picture shows the recent paint job and condition of the rear end of the truck. More pictures to come soon!

 

I belive the first picture is your carb heat pipe. A flexible metal hose goes from that to your aircleaner.

The other two pics are nearly indeciphrable and I belive they are what remains of your EVP emissions system.

Did you do the codes while KOER or a KOEO? This tells me what to tell you to look for.

Generaly,
18 is a tach signal loss and meens your spout conector is gone.

41 is a O2 sensor low voltage signal and most likely means your O2 sensor is shot or you need a good ignition tuneup.

63 is low TP sensor voltage. THis is usualy a wiring problom.

Unless your state has smog laws it is often cheepest to install a electic choke replacement carb from the 70s and convert to durasparkII. This is a straightforward bolt in swap. IF you need more help and have patience I and others will walk you through this.

 

What Flip said. You have a truck equipped with the DFC (Dreaded Feedback Carb). Just like EFI, the DFC has to have everything connected and working properly for your engine to run properly. Change out to at least an '83 or older carb and the DS2 dizzy and ignition system and you will be good to go.

 

Trouble is fellas, he DOES have to pass emissions in Colorado. My buddy has a 76 E100 and has to pass this year.

Unless you're willing to take a chance that the state test facility won't notice that you've changed over, you'll want to maintain what you have. The "DFC" isn't so dreaded as some say. I'd start with a new TPS and an O2 sensor, then check the codes again. Your spout connector is a plug hanging from the dizzy wiring just next to the dizzy- make sure it's connected. In fact, I'd take it apart, clean the connection, and put it back together.
Also, give the carb a twist while it's on the engine. If you see movement, pull the carb and tighten the three or four screws that hold the bowl to the throttle section. I've had to do it several times.

The tube in the second pic is supposed to be attached to the smog pump (you're calling it a compressor). The larger hose connects to the air filter to provide warm air to the carb during cold operation.

The black smoke is a dead giveaway of a choke that's adjusted too tight, or the O2 sensor is damaged, making the computer go into limp mode, which causes the carb to dump too much fuel into the engine.
Let us know what you find.

 

One thing outa wack on a feedback carb and the choke stays shut. Best thing to do on EECIII is get rid of it if you can. Check the state laws. Some states exempet you if you can still pass the tailpipe test for older vehicles.

 

In CO, he has to pass a visual inspection. No feedback system=no pass.

Camo,
I'd like to see you convert over to DS II and a regular carb, but you're looking for trouble when you get your emissions sticker.

 

Fortunately, for now, the truck is (and will be for a couple more years) registered in North Carolina as I have student status in Colorado and am originally from North Carolina. The problem wouldn't arise until I decide to re-register it in Colorado.

However, after adjusting the carb the other day, the truck now wont start. I had it idling perfectly, not rough at all. I ran it a few times over the next 24 hours to check and double-check the idle and it started perfectly. When I finally got ready to drive it after adjusting the carb, it died when I put it in gear and now will not start.

 

Actually (what Wyowanderer said) the DFC is not a bad system IF...(operative term "IF")...it is properly maintained. For those that fail and/or refuse to maintain the system, it is the DFC.

 

Heya CamoLaw,
Welcome.
The first picture is a heat tube. It collects the external air warmed up from around the exhaust manifold. There's a flexible hose missing that runs up to the inlet to the air cleaner. If the engine has the stock air filter, there should be a hose running from the filter to up near the grill. Almost directly above that pipe you have pictured should be an opening on the underside of that air inlet.
It's designed to feed warm air into the intake when it's cold outside.

The second picture looks to be an air bypass valve for the Smog pump. It's a one way valve that allows fresh air from the smog pump to go into the exhaust, but blocks hot exhaust gases from exiting. On my '81, (not a feedback carb setup), it was in the pipe that ran from the smog pump and into the EGR spacer.

Not sure on the last picture. Can you get a clearer shot?