I. Have a 2003 Ford F-150 King Ranch. The problem I have is that it doesn’t want to start once in a while. It doesn’t matter if it is cold or hot or if it has been running then turn it off and it still won’t start back up sometimes. I’ve replaced the feul relay,checked the fuel pressure when it doesn’t start and all that is fine. Most of the time when it doesn’t start I can use starting fluid and it will start right up. But. Every now and then it doesn’t matter what I do it just won’t start at all even after trying everything that I usually do. Then I will just let it sit for about 15 minutes and it will start right up. Their has only been one time that no matter what I did it wouldn’t start at all. It was facing down a hill at a campground I was at and it was in the way to get my camper out of the spot it was in so after trying to start it all day a friend went and took his camper home then came back to get mine. So when we got back I tried to start it again and no luck so he pulled my truck up and out of the way and after unhooking the vehicles I tried to start it and it started right up. And one more thing I seen the other night is that my headlights come on by themselves then go right back off
If it cranks ok, the headlight symptom probably isn’t related to the no-start. Fuel pump is what I’m thinking.
It could be an inertia switch problem if your vehicle has one. I have owned several Ford Rangers and bypassed all the inertia switches for similar problems. They are problematic as they age.
As it starts fine with starter fluid, this seems to be fuel related.
What happens when it starts? Is there a black smoke from exhaust?
Are you sure your battery is fully charged? It is possible that sometimes it doesn’t have enough ‘juice’ for all consumers.