The dual fuel tank selector valve on an 89 Ford F250 is typically located
underneath the vehicle, near the fuel tanks themselves. It's often positioned in a somewhat central location between the two tanks, but its exact placement can vary slightly depending on the specific body style and modifications. You might find it near the rear axle.
It's usually a lever or a knob that allows you to switch between the tanks. Because it's under the truck, you'll likely need to get underneath to see it. It's a good idea to consult your owner's manual (if you have it) or a repair manual specific to your 1989 Ford F250 for a diagram showing the exact location.
