Extremely high hydrocarbons

[Doity]

I have a 1991 GMC Jimmy and i went to the emissions place and it failed. the limit for hydrocarbons at idle in my area is 220 ppm and my truck was pushing out 831 ppm. Also the CO+CO2 % at idle was double the limit as well.

I know that a tune up could do alot toward bringing the hydrocarbons down. I dont have enough money to do a full tune up till i sell my other car. But i was going to go ahead and buy new plugs and wires and an air filter.

Is there something else i should be doing? i heard that a clogged catyalytic converter could be the cause of some of the high levels.

I also have a vacuum leak. I know where it is, but the line goes back behind the engine and underneath the firewall which is where the leak is. So thats going to be a fun job.

Any tips or tricks to get the hydrocarbon levels back down would be awesome. I need it to pass emissions so i can transfer it into my name.

Thanks in advance guys.

[BernieB]

You're not gonna like this but... I'd start with the vacuum leak, and probably the air filter (if it really needs replacing) to get the air/fuel ratio back in line. You can pull a plug or two and inspect them to see if they really need replacing. Chances are they're starting to foul and you'll have to anyway. Save the wires for last and see how it runs after you fix the other stuff. And add some SeaFoam to the tank, it'll help.

[Doity]

Getting the vacuum leak fixed was on the top of the priorities. It is just going to be a pain to get to.

Any suggestions?

Thanks for the advice.

[mudseeker]

hydrocarbons are nothing more than unburned fuel.
smoke test your evap system, could be a bad purge valve, or the canister is flooded and needs replaced.
check cylinder compression
fix the vac leak
clean the injectors
check the ignition system
put it on a scantool and check the misfire counts per cylinder.

(in no particular order)

[Doity]

Before i go to get it re tested i am going to replace the distributer cap and rotor and put all new plugs and wires. Should i replace the coil as well?

There is a stuff that is called Garaunteed to Pass. i dont know if they sell it where you guys are at. Does that stuff clean the injectors? or does it just temporarily lower emissions?

Also, how do i know if it has a bad purge valve? or if the canister needs to be replaced?

I'm sorry, i am not very mechanically inclined. But thank you to everyone that is helping me.

Thanks again everyone.

[gmctrucks]

Go to You-Tube so you can see how to apply Seafoam using the brake booster line. Also check your timing it should be at zero but you have to disconnect the purple or brown wire by the fire wall somebody else will chime in to tell you the right color. Delco plugs or NGK plugs are $1.99 at O'Rielly's also don't buy Bosch plugs GM trucks don't like them and if you replace your wires don't buy cheap Auto Zone wires or do like Bernie said test them by yourself first. Do you live anywhere close to Houston I could help you if so.
Good Luck! GMC

[Doity]

i will definitely have to look up how to use the seafoam stuff.

I live in Tacoma Washington. And i don't think there is such a place as O'Riellys. But we have NAPA. And i bought i can't remember what they are called. But the man behind the counter said they were the plugs that GMC used or uses stock.

What defines plug wires as cheap? Napa's middle ground wire set is 40 bucks.

You all are life savers. Thanks again

[gmctrucks]

Napa parts are super I would go with what they recommend. What I meant about cheap wires is like some $10.99 wires from Auto Zone or K-Mart that will give you more problems then some old Delco wires. I have MSD wires on my truck that are 8mm I think or bigger now they have been real good considering that all my ignition system is MSD. I love Napa parts one can't go wrong with there parts.

[BernieB]

I wouldn't spend the money on wires, cap and coil until I saw how it ran after the vacuum leak was fixed and the plugs changed. Just from the readings you gave I figure it has to be idling pretty rough to start with. If fixing the leak and changing filters and plugs gets it idling smooth again why spend the extra money, especially when you said you couldn't afford it?

Now, if that's changed (maybe you hit the lottery?) then by all means, go right ahead and change out the wires and anything else you care to change. New parts aren't going to hurt it any. But if your budget is still a concern, do this step-by-step and then stop when you get it fixed enough to pass.

[Doity]

thanks guys. I thought about the wires thing a little bit yesterday. and decided i couldnt afford them, so i just bought the plugs and an airfilter. Then i log on here this morning and you tell me to take it step by step. I find it funny.

After i changed the filter it seemed to have a little more pick me up from 0 to like 15-20. but it doesnt really accelerate very quickly after that. Thats another beast for another day. lol. thank you guys.