1988 toyota pickup failed "idle emission" in WA

[quote:c9fa362c45="sqa4life"]My 1988 pickup regular cab runs like new, it has 173k miles, 4 cylinders, 5 speeds, carburator.

I brought it to the emission test station in WA and it failed on the "Idle Emissions". The reading said as below:

Idle Limit:
HC (PPM) = 220
CO (%) = 1.2

Idle Emissions:
HC (PPM) = 314
CO (%) = 3.78

The temperature takes too long to get to 1/8 hot. It never gets to the middle of the Hot/Cold temputure like other normal car/truck.

Please advise.

Thanks

sqa4life@gmail.com[/quote:c9fa362c45]

If you are saying that your temperature of the coolant never gets warm, then replace your thermostat. Your thermostat forces the temperature in your engine to rise to the proper level to burn the fuel/air mixture properly.
I would replace the thermostat, and drive the truck on the interstate for about 15 minutes before attempting to retake the test. If it still fails, you will need to replace the plugs and wires to make sure the mixture is burned completly.

[quote:5d02c439a1="Mikeybdman"][quote:5d02c439a1="sqa4life"]My 1988 pickup regular cab runs like new, it has 173k miles, 4 cylinders, 5 speeds, carburator.

I brought it to the emission test station in WA and it failed on the "Idle Emissions". The reading said as below:

Idle Limit:
HC (PPM) = 220
CO (%) = 1.2

Idle Emissions:
HC (PPM) = 314
CO (%) = 3.78

The temperature takes too long to get to 1/8 hot. It never gets to the middle of the Hot/Cold temputure like other normal car/truck.

Please advise.

Thanks

sqa4life@gmail.com[/quote:5d02c439a1]

If you are saying that your temperature of the coolant never gets warm, then replace your thermostat. Your thermostat forces the temperature in your engine to rise to the proper level to burn the fuel/air mixture properly.
I would replace the thermostat, and drive the truck on the interstate for about 15 minutes before attempting to retake the test. If it still fails, you will need to replace the plugs and wires to make sure the mixture is burned completly.[/quote:5d02c439a1]


Thank you for your advise.
I replaced the thermostat, flushed the cooling system again, replaced all spark plugs, wires, cab & rotor and drove it for two days. Just took it back to the emission. Unfortunately, it still failed. However, the CO (%) got down to 2.6. That's more than 1.1 below the first test. The inspector said I have to get the CO (%) to 1.2 or below to pass the emission.

What would be the next step?
take it to the shop and rebuilt the carburator??

First off, how long did you drive the car before the inspection? I know for the best results, you need to drive the car at a high steady speed to allow the temperature to get to its maximum level to burn as much fuel/air mixture as possible.
If your truck is not running good, then a carb rebuild may be in order. However, if the truck runs good, it sounds more like an emissions system problem. Here are a few things in the emissions system you can check. Check thermal expansion tank for deformities or cracks. Check charcoal canister for clogging and clean if necessary. Check all hoses for deterioration, damage, restriction or collapse and repair or replace as necessary. Also check hoses for tightness on fittings.
How the emissions system is supposed to work, is when the O2 sensor senses the fuel/mix is not burned completely, it opens the EGR valve to recycle some exhauast back theu the intake to reburn the mixture. The system trys to get the fuel burned enuff to where the catalytic converter can burn the remaining fuel and give us very low emissions out of the exhaust. The reason I asked about how long you drove the car before testing, is you want that catalytic converter to be up to temperature so it will do its job of burning the remaining fuel before it hits the test machine.
Now, if your truck runs poorly, or you cannot find anything wrong with your emissions, then it may be time to take the truck to a mechanic that you trust.

Conditions of the Air filter and PCV valve. Drop the mixture qtr turn.

Or pull a vac hose

Bottom line its a Carb problem.

Thanks everyone for your help.
I have done everything.
I think I'll take it to the mechanic to have the carb adjust.

Thanks again.