My ol' girl just failed her e-test. The "curb idle" test passed although the HC ppm were on the high end. The "ASM 2525" test though, she scored a 242 HC ppm (limit 60) and a 1.88 CO% (limit .33) while barely passing the NO ppm with a 645 (limit 675). What strikes me as odd is the RPM for that test was only 917, seems low for a cruising test... Any suggestions before I pull a plug and take a look, and check my vac lines?

Probably unrelated but my fuel tank pressure control valve beside the evap canister was buzzing loudly by the time I got it home. Never heard it before, didn't even know it was there. A symptom of a fuel system issue perhaps?

 

Any ideas? My college course is finally done, time to work on the ol' girl.

 

Just pulled two plugs and they both look perfect. Checked my evap canister, not full of gas. Checked the vacuum line on my Holley AFPR, also not full of gas. I did however notice two things: One, my fuel rail shraeder valve leaks a little. And two, my fuel pressure was pretty low (a little over 30 psi with the vac line off). Could LOW fuel pressure cause high CO and HC?