When I failed my emissions I was told it was because it was running rich. I put some fuel system cleaner in the tank and I'm halfway way through the tank now. It still runs rough, at times, at idle. When it's running rough it has bluish smoke and black flakes on the ground under the tailpipe. I figure the black stuff is from the cleaner in the fuel but I'm not sure. I disconnected the AAP and it didn't make a difference.

Thoughts?

if your truck is running rich it is extremely rich. i know my truck is runs a little rich but the only way i can really tell is a little black "soot" around the end of my tail pipe. im not sure why it would be running as rich as it sounds, i know someone on here can help you though. what year/ engine is in your truck?

I would guess it's running extremely rich based on the emissions test and the tailpipe being all black. I'm looking for anything I can check. I bought a carb rebuild kit and am considering replacing all the diaphragms. I wonder if I should drop down a jet size since the truck was originally bought in Texas. It's been here (Denver area) for at least seven years.

It's an '83 22r.

I discovered this morning that the idle mixture screw will not lean out the engine enough to stall it. It did the other day but no longer does. I guess it's time to take it apart.

>>>*Best to pull the dipstick and sniff the oil, if you smell fuel, you must change it. If the engine is running rich and fuel residue builds up in the oil, it will make the engine run even richer and also begin to consume oil.

The oil level doesn't drop rapidly because of the addition of fuel but this is a very bad situation for the engine.

The sign of this happening is exactly what you describe, damp looking sooty deposits spit out the tailpipe combined with some blue smoke....*EB

I'd planned on changing the oil before going back to recheck emissions. I want to correct the rich mixture before changing the oil again. Would you change the oil first then (I don't smell fuel in the oil at this point)? Any suggestions on what to look at for the rich running condition? All the tune-up parts are new and the timing is 5 degrees with the vacuum removed (can't get it to 0 degrees as the distributor reached the stop). The idle is a bit rough and the idle mixture screw when fully leaned will not stall the engine.

Replace the exterior diaphragms (AAP and AP), and make sure the choke is releasing all the way. Screwing in the idle mix screw all the way should just about kill it. If it still runs, something isn't right. Also check into that timing problem... should be 0? base and then 12? at idle with the vacuum advance reconnected.

I removed the distributor and moved one tooth. I could basically get it to 0 degrees when it at the stop in one direction or 5 degrees at the stop in the other direction. There was no way to get it to either setting with enough room to advance or retard it. BTW, what degree is the farthest left mark? I have | | 8 5 and, with the vacuum on, it's on the far left mark. I'd assume the second mark is 12 degrees.

I'd disconnected the AAP and plugged each end and nothing changed. The fact that the idle mixture screw seems to not work right makes me think I should take the carb apart and clean it. I just don't know if that's going to do anything to the high idle. I can buy a rebuilt carb for $250 and I'd expect everything to work properly. I don't want to spend the $250 if there's a decent chance that won't fix the running rich problem.

Thanks for the help, I think we're getting somewhere.

| 12 8 5 0

^ That one?

And a word about rebuilt carbs.

I too spent $250+ on a rebuilt carb figuring I could count on everything to be right. Since puttng it on, it's taken me about 6 months of tinkering and fine tuning, and diagnosing and replacing defective parts. First, the AAP diaphragm sealing surface on the metal part was never cleaned up after it was stamped out, so I had to resurface that with a knife sharpening kit. Then I figured out that the outer vent control valve wasn't working and had to replace it with a junkyard item. I'm still not 100% satisfied with the float level, but I really don't feel like tinkering with it again for a while. I've had to adjust every single screw on it, and the choke was set too tightly from the word go.

I'm not saying you for sure will have these problems, but you probably shouldn't expect to be able to slap it on and go. It will take adjustment, and maybe a lot of it to get it just right.

Yes, except mine doesn't have a 12. It's got | | 8 5 0.

I decided to take the carb apart myself figuring I might run into what you describe. It had obviously been rebuilt recently as it was very clean and all diaphragms and seals were in great shape. I still cleaned it all although I have no faith it will fix my problem.

First things first, though, I've got to figure out how to get the throttle linkage back on! I took a digital picture before-hand but it's not got the detail I need.