I have a 98 K2500 suburban with a 454 (54K miles) that won't pass the
idle emissions test. It fails with a high hydrocarbon reading of 416,
the test limit is 300.
The vehicle had a tune-up approximately 1,000 miles ago. A local shop
ran a diagnostic test. Results indicated that the fuel pressure
regulator was at fault.
I changed out the fuel pressure regulator and had the emission test
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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