Storytime: I have an '07 Ranger that I just acquired about a year ago, but this could apply to almost any Ford truck.

One day, the truck wouldn't start. It cranked just fine; it did everything except start.

I searched around and right away found lots and lots of posts, videos, etc., explaining that Fords have these fuel pump gravity switches which, when triggered, cuts off power to the fuel pump and must be reset.

Okay, it turns out that despite the truck NOT having been in any recent collision or suffering violent activity (i.e,, the conditions that are meant to trigger the switch), the switch was triggered and I reset the switch and things were fine.

A week or so later it happened again, but this time when I went to reset the switch it felt like it had not been triggered, but I figured it had to have been, and the truck started up so I decided maybe I should swap out the switch.

It was fairly cheap and easy to do myself, so I did. And then, about a month later, it happened again, and the switch had definitely NOT been triggered.

So what happened? What was going on?

Here's the key to the story if you can't start your truck and you know you have a good and un-triggered gravity fuel pump switch.

During this entire period of time, my truck is usually parked in my driveway, which has a slight upslope. I'm not sure if it matters, but I also park it at a bit of an angle. I don't drive it much, so sometimes it sits there for days at a time, sometimes as long as a week.

What I think has been happening is that the fuel somehow drains away from some key component due to gravity as the truck sits on the slope, and won't start.

The solution is something I picked up reading about the failed or triggered gravity switches. Before starting the truck, I switch the ignition to on, then turn it off again. I think this has the effect of priming the fuel system. One video said to do this three times as a reset procedure after resetting the gravity switch, but I do not believe it is a required reset procedure. It is probably just a priming of the fuel system after power to the fuel pump is restored.

So if your truck won't start but seems like it should or is about to, try turning off the ignition, turning it to on, turning it off again, and then try starting the truck again.

And if anyone with greater technological knowledge can confirm what is basically my perception and supposition, please do so.

 

In my truck, 1993 Ranger 3.0 engine, the fuel pump runs for about one second after ignition is turned on. This pressure-primes the fuel system. I always listen for the fuel pump before starting the engine. If you don't hear the pump, replace the fuel pump relay with a known good spare. Once I thought the fuel pump was bad. It was only an intermittent fuel pump relay. I also check that the relay contacts are clean every few months and smear them with dielectric grease to inhibit corrosion.