Symptoms: long warmup time, low operating temp of ~170*F, heater blowing lukewarm air. The new thermostat I just installed will hopefully cure these symptoms. With increased operating temp, emission levels should be closer to optimal. I put on a new radiator cap as the current one was coated with antifreeze residue, probably because it was leaking.

I'm a little late, but spring sprung a few weeks ago in the "low country" here in Denver as evidenced, first, by our crocuses making their brief annual appearance.



Now that spring is upon us, four wheeling season is only ... 3 months away. Fishing is another story, and I've heard rumors fishing is good at Antero Reservoir.

The daffodils were next to appear.



We also had a batch of baby bunnies out back. They've since scattered off to seek fame and fortune.



So signs of spring have me itching to get outdoors. Maybe an easy family four wheeling trip in the lower elevations is in order. First we need to see how Violet reacts to the noise of the Jeep.

This is turning into one of those weeks where I need to just put down the tools and go read a book.


Tailgate lifter channel (source: Berkeley's Full-Size Jeep site / BJ's Offroad)

I was in the middle of installing the rear window during my lunch hour here. I had just reglued the glass back to the tailgate lifter channel, was this close to being all done... and a tool slipped and *crash* ...

Now my rear window is nothing but a bunch of tiny little glass fragments sitting in my shop vac... and on my driveway... and in my tailgate waiting to cut me every time I have to dig in there to fix it again. If I do (fix it again, that is) I found a good tailgate repair writeup at Berkeley's site.

Now the hunt for new glass is on.

I'm debating whether I should get a new lifter and seal from BJ's or not.

It's time for Colorado emissions testing again. Here in Colorado, vehicles newer than 1982 have to undergo the IM240 dynamometer emissions test. The limits for a 1986 vehicle are 40 grams per mile for CO, 6 gpm for HC and 4 gpm for NOx. For an old vehicle like TC with a simple old carburetor, getting through emissions can be tough.

I just helped Scott get his 1986 converted Wide Trac through emissions. It barely squeaked through on the 7th (yes, seventh) try. Last time I was able to blaze through emissions with loads of room to spare. Since FSJs are known to Colorado Air Care as "gross polluters", regularly failing emissions with massively high numbers, here are some lessons learned on how to pass emissions. Legally, mind you.

Tuning
You need to maximize your vehicle's performance so that less gas pedal is needed to get it to speed, meaning less fuel and less emissions. Install new spark plugs and spark plug wires, cap, and rotor as needed. Also, get your idle mixture dialed in just right, set for a lean best idle -- after you ensure the power valve and base jetting are set (see below).

Set the timing to maximize part throttle power at highway speed. This is where you'll have the most vacuum advance and mechanical advance. Spark knock -- even if you can't hear it -- will compromise performance, as will timing that is retarded too much.

I find that a little more vacuum advance, if you have some leeway in the NOx readings, can help to burn some HC. I can't prove it but I think it may reduce CO (maybe by improving performance, I don't know). NOx will increase due to increased combustion temps which is why you need the leeway.

One could write a book on carburetor tuning. Well, look at how many people have! Heh. Best to go read some of those books. But I'll add one more thing. Fuel pressure and float level affect mixture.

Failing Power Valves
The FSJs with Motorcraft 2150 carburetors frequently have power valves that go bad, releasing fuel into the mixture all the time. The power valve is supposed to come on only under load. In this case you'll see CO numbers in the 80-200 range -- way above the limits. With a new power valve you should see numbers in the 30-60 range. I've always used 2-stage power valves on the 2150's to pass.

Failed Aneroid
I didn't know this until we found the aneroid had completely failed on Scott's rig. Failed shut, meaning the A/F mix was way too high. This brought his numbers down from the 80 range to the high 30's. I think the old aneroids get stiff since they contain a brass bellows which surely work hardens over 15-20 years.

Base Jetting
Possibly because of stiff aneroids, I've had a lot better luck switching my 2150's from the base #55 or #56 jets to #52. I've done this on 3 rigs now. Backhoe ran a little lean this way. TC was undriveable. And Scott's rig runs just a hair lean. All three were able to pass the test.

To fix TC I used a spare aneroid and did the unthinkable -- I adjusted this part that was never intended to be field adjusted. I used it to richen the mixture back up by closing off the valve a tad. This is how I blazed through with ridiculously low HC numbers. I also started getting much better gas mileage. Without a loss of power!

Accelerator Pump
It's possible your accelerator pump is set wrong. Setting the linkage to the innermost hole reduces the amount of pump travel and hence gasoline injected on acceleration. The outermost hole causes a lot of pump travel and a lot of gas injected. You want it set to factory or, if you can get away with it, an inner setting, provided everything else is calibrated right and this pump setting doesn't introduce hesitation off the line or from cruise.

Emissions Vapor Canister
Since the engine draws in air with a bit of fuel vapor from the vapor canister both at idle and part throttle, it stands to reason that disconnecting the purge line from the PCV and plugging the PCV inlet will enrich the mixture somewhat. Disconnecting the purge signal line would enrich the part throttle load mixture. I don't have hard evidence to indicate how much of a difference this makes. Meanwhile, a bad purge valve may leak air, leaning the mixture. You may need a replacement emissions canister.

QuadraJets
I had really good luck with the Qjet I put on my truck, passing the first time through. I think these carburetors tend to atomize fuel better resulting in lower emissions and better gas mileage. If you can get your Qjet tuned correctly for your engine I would expect it will do nicely year after year. There's no power valve to go bad. Just watch the fuel pressure and float level.

Edelbrock Performers
I've had the worst luck with my AFB and Performer carbs and have gotten worse mileage with them. I think they tend to atomize fuel worse than the Qjet or 2150. Or maybe I just never figured out how to tune them, but I did try several combinations of rods and jets and always struggled to get through emissions with this carburetor design.

Other Stuff
These are the most common failures I've encountered. Colorado Air Care has a list of suggested fixes for the FSJ, too. There are other basics to follow like changing the oil and air filter, running a can of SeaFoam or other intake cleaner through the engine as directed, ensuring proper operation of EGR, AIR system, catalytic converter, and overall good mechanical condition will all help -- and may be necessary to get through emissions.

The Air Injection Reaction (AIR) system helps the catalytic converter oxidize HCs and CO during acceleration and will help to oxidize HCs out of the exhaust ports at other times. EGR will help to keep NOx lower by reducing combustion temps during part throttle, so you can get away with more timing advance. The catalytic converter will reduce CO and HC through oxidation and some will break down NOx as well.

Ambient temperature seems to matter. Very cold days mean dense air and lower A/F mix on at least the 2150 if not other carbs. Very warm days have thin air and richer mix. It might make enough of a difference to fail on a warm day and pass on a cold day.

If your engine is weak, or transmission slipping, tires low, I suppose all this could contribute negatively to your emissions test results.