| 摘要 |
An automotive fuel filler pipe cap detection system has a filler pipe cap retainer on the end of the filler pipe for retaining the filler pipe cap, a passage through the cap retainer with a line outlet leading to a vacuum line connected to a manifold, and a seal outlet leading to the underside of the fuel cap when it is in place. Vacuum is generated in the vacuum line when the engine is started with the cap covering the seal outlet. A two position pressure switch connected to the vacuum line is in a first position when vacuum is sensed in the vacuum line and a second position when vacuum pressure is not sensed. A "fuel cap missing" indicator is lit to warn the operator when the switch is in the second position.
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