My Truck Dies When Passenger Rides

My 2003 Ford Explorer Sport Trac only dies when someone rides in the front passenger seat.
Then it won’t start for at least 30 min to an hour. The time seams to vary. There is no warning light, no motor sounds or any kind of warning at all. It just dies. When trying to start it cranks great, no signs of battery drain. I think it’s the auto shutoff wiring in the floorboard that goes to the reset button for the fuel pump. I tok it to a dealer and they put in a new fuel pump. $1000 later that night it did the same thing. I had a friend in the passenger seat. I took it back the next morning and they kept it for 3 days but could never get it to die. So my thought is they never had a passenger. I tested it myself in my driveway and stomped my feet around the floor and it died.

What do you think?

They replaced the fuel pump? Did they test it first?

Could be the inertia switch. The following links contain some images showing how to test the inertia switch, where the inertia switch is located, and what it looks like, and what a new one costs.

Go for it. And never darken the door of your local dealership again. They did you no favors.

It’s a good thing the problem isn’t reversed…

A big +1 for @thesamemountainbike.

Thanks. I’m truly humbled.