Hi Brian. You brought your 1991 Chevy Prism in because as you stated the engine turned over but would not start for about 10 seconds. We spent roughly ½ hour diagnosing this problem which you were charged for and was listed separately as only a diagnosing fee. We first checked the charging system with a tester that includes the battery, alternator and starter, Check ignition system, Checked battery and starter connectors & hooked up our scanner to check the PCM for any codes. We also pulled a spark plug out to check condition. We could not duplicate your start issue and we recommended to do the tune up because of old and worn plugs. I called you and recommended at this time to do the Tune up and you agreed. The labor charge to do the tune up and air filter was only $71.74. After we did the tune up we test drove the vehicle. I hope this can help you understand the labor charges.