JMH , I just had that problem , motor kept running on . Then got out vacum tester because my fuel door would not lock anymore and I took the unit out and found out it was bad , so I just bypassed it until I get a new one. But motor still ran on and had to shut it down manually a few times , I went around and around a few times and started looking under the hood and found that on the main vacum line cigar hose there is a two port check valve , one of the ports was not drawing in any vacum I tried to poke it clean but still no good . I plugged it off and put a tee branch off the one next to it and now the motor shuts right down every time. All vacum works but does not hold door locks all day, sometime I will check all of the other fittings and replace the cigar hose . Hans.

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A couple of Ford pickups F 150,250, 350 missed.
1983 240 D 256,000 miles ,auto, ac.