It failed twice on the pressure test and also the hydrocarbons & carbon monoxide (it's running rich) I changed the spark plugs, air filter, even the oxygen sensor and the gas cap. Any advice would be GREATLY appreciated!

 

Check to see if the cat is plugged or bad.

 

A little info on the vehicle in question would help. But I agree with the post above. Failed cat will cause increased hydrocarbons at the tail pipe. Tap it with a rubber mallet and see if it rattles. Check the inlet and outlet temps. Should be hotter on the back side because of it burning those hydrocarbons.

 

Could be so many things... cat, vacuum leak, the other O2 sensor, leaking manifold, and on and on and on. What year, what engine, and can you show us the actual numbers?

 

Pressure Test

I Think in NJ they overdo the pressure to blow out and fail your jeep.

This failure could be an old, rotted filler tube, failing fuel pump gasket, defective rollover valve or the grommets on top of the fuel pump that pass the wiring could be leaking.

Hope this helps.

 

STEELERSgirl said:

"I live in north valley, Phoenix and I'm new to this forum. I have a '89 Cherokee Laredo 4WD with 203,500 miles on it. I love how it just keep on going!"

 

It's always the most expensive item -> cat

 

Ahhh, okay. You wouldn't happen to have her smog results, would you?

STEELERSgirl, check the vacuum line that runs from the back of your throttle body to your MAP sensor (mounted on the firewall behind valve cover). It's prone to cracking/leaking and if it does, you'll run really rich.