smog > hydrocarbons at about 11 times higher than allowed

[slaterson]

got my 84 fj60 smog checked yesterday. hydrocarbons are at about 2500, need to be under 220. this is the first time it's failed the check, i've owned it fhe past 6 years, 4th time i've tested it (first time when i bought it, the every 2 years after).

testing lead up - about 1/2 tank of gas, 5 minutes to highway, 5 minutes on highway, then ~10 minutes in stop and go traffic to the smog place.

any thoughts on what i need to check first? from browsing, seems the air injection system needs to checked to ensure it's working. would that cause such a high HC output?

i have about 5 weeks to get it to pass, otherwise i have no valid tag.

 

[Mark W]

A bit more info would help. With nothing more to go on beyond "high hydrocarbons"... it could be any one of 27dozen things. Or a combination of 2-17 of them.

Does the rig run smooth? Run strong? Run weak? Any quirks? Smoking/burning oil? Last tune up? Start easily? Start hard? How many miles on it? What sort of compression numbers? All cylinders seem strong, or is there a miss or stumble (cold, warm, both)? How do the plugs look? Vacuum leaks? Exhaust leaks? Last valve adjustment?

I can tell you this much though... the air injection system can not compensate for that much unburnt fuel.

Mark...

 

[OSS]

There"s a whole lot of unburned fuel entering the exhaust pipe.

 

[toy_tek]

I recall reading years ago that HydroCarbons build up in motor oil. A fresh oil change can reduce HC readings, it worked for me in getting a motorcycle to pass emissions once. However I doubt that alone would drop yours by 10x.

 

[Roonie]

Are you testing out of requirement or curiosity? I assume requirement so it must be Oregon.

 

[slaterson]

will try to answer all the questions and provide some additional info as requested.

1) i am testing out of requirement. without a passed test, i can't renew the tags on the truck. this is the first time it's failed since i've owned it (6 years).
2) i drive it about 1,000 miles per year, maybe a little less. the oil has been changed in the last year. i don't change it every 3 months because it barely gets miles put on it. would an oil change really make a noticeable impact?
3) no visible smoke from the exhaust or any where no the truck. there never has been during my time as owner. i put a new exhaust on it when i took ownership. everything passed visual inspection, it's just the hydrocarbons.
4) it runs fine. started fine when cold, and only stutters slightly when it's cold during the first 30-60 seconds if i start accelerating before it's fully warmed up. otherwise, it's always run great and no visible signs of anything wrong.
5) it does have a small gas leak. if the nose is lower than the back of the truck, gas does drip slowly around the inside of the passenger side rear wheel. when not in use, it's natural parking spot is a slight uphill with the front on this higher ground. i found the leak by coincidence when i had it backed in.
6) the exhaust has always smelled pretty strong, it smells very strong right now. i'm not sure if thats just me being more sensitive to it since i need to get it tested and passing, or if it's actually much worse now than it has been in the past.
7) it's got 268k miles on it.
8) have not tested the compression, vacuum lines, etc...
9) i had to bypass gas shutoff during deceleration due to stalling. i did that 2-3 years ago, and it passed smog check since i originally did that. nothing has changed with that.

 

[John Smith]

If you have a timing light, hook it to each individual cylinder plug wire and verify all are firing. Next pull the plugs and inspect. That should help point you towards ignition issues, or carb issue.

 

[slaterson]

a lot has been done. new plug wires, plugs, valve adjustment, oil change, new converter, ... i can share a full list if it's helpful. that got my hydrocarbons down to the point they are well below allowable levels. however, my CO has jumped from 0.04 to over 6, and CO2 has gone up as well. allowable level of CO is 1, and CO+CO2 is 11 or 12.

anything specific to do about the CO?