any quick tips on passing emmissions?

**chazawazzle** · 01-03-2009, 02:13 PM

hey guys.
i just found out that the 1991 1500 sub that i got needs to pass emmissions. I was wondering if anyone has any quick tips to pass? it has a tbi 350 with 240000 miles but it looks like everything under the hood besides the block is bran new.
any tips?
thanks

**PencilPro** · 01-03-2009, 07:16 PM

I would say take it and see what happens.
I think that will get you a starting point.

**chazawazzle** · 01-03-2009, 07:57 PM

the guy said that all i need to do is to replace the gas cap and it will pass!

**PencilPro** · 01-03-2009, 08:07 PM

Originally Posted by chazawazzle

the guy said that all i need to do is to replace the gas cap and it will pass!

The smog control on your vehicle runs a pressure and vaccum (howerver you spell vaccum LOL)
test on the fuel tank. I'm not so sure about that causing it but it is a part of the smog control.
In 91' they didn't have a check engine light come on when it runs this test.
I don't see that being the problem but if it was that would be a cheap fix for sure.

**gassy** · 01-03-2009, 08:30 PM

Most emission tests will test the gas cap with a vacuum device, replace it if it needs it. However the best is to do an oil change ( clean oil will release less stored HC into the PCV system at idle). Also a good hiway run 15-20 miles will make sure everything is hot, especially the cats and O2 sensors. Do not shut the truck off when you are in the lineup, keep it right up to temperature.