I have a 98 K2500 suburban with a 454 (54K miles) that won't pass the idle emissions test. It fails with a high hydro carbon reading of
416, the test limit is 300.
The vehicle had a tune-up approximately 1,000 miles ago. An independant shop ran a diagnostic test and indicated that the fuel pressure regulator was at fault.
I changed out the fuel pressure regulator and had the emission done again. Results were the same as before.
The engine runs pretty smooth at idle, but will miss occasionally.
My first thought will be to look for vacuum leaks.
Any suggestions would be appreciated.
Thanks in advance.
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