does anyone know how to use the evap test port on a 2004 cherokee with a 4.0.. getting a small & large evap code

 

Just went thru this on my 01 xj. been a pain in the butt for a bit. Bought a amazon smoke machine with fluid for cheap. Remove the valve core from the test port. Install smoke hose and turn on the machine. Found my leak on the drivers side rubber hose connection. hard pipe to hose to hard pipe. It was behind the fuel line. would have never found it with out the smoke.

 

i smoke tested it from the hose coming off the purge valve.. couldnt find a leak and when i opened the gas cap the tank was filled with smoke

 

The test port is on the evap line near the charcoal canister, back by the fuel tank. You'll need a smoke machine to use it properly. That's the only real way to find the leak causing your codes. The port is just for connecting the tester.

 

this is the type i have. so the test port by the purge valve isnt where you insert the smoke tester?

 

Green cap, remove cap, there is a tool to remove the valve core. Threads are backwards. right to loosen, left to tighten. I bought the tool off amazon and the adapter hose as a set.