This truck won’t start after a short drive

Question:

I have a 1995 Ford Ranger XLT that I purchased new. It has been very well maintained and I love my truck to death except for one problem. Going on three

or four years now, my truck will not start after a short drive. For example, I can start the truck fine in the morning and drop my kids off at school, but when I return to the truck five minutes later, it will not start.

At the beginning of this adventure, I would simply wait five to 10 minutes and then it would start. Within the last two years, I have had to tow it to my mechanic three times and once sitting in front of his shop, it would start fine. He can’t replicate the problem and therefore he can’t try and fix it. Well, finally it wouldn’t start even when towed.

Now, to quickly summarize what has been done to the truck, it has gotten a new fuel pump, new computer, new relays, swapped relays, checked and cleaned all wires going to relay box, and so on. We’ve spent hours of time trying to figure out what is going on. Even after all of this, the same problem will happen. I will drive a short distance, come back within five minutes and it won’t start. I started jiggling the relays and the box and this actually works most of the time!

My mechanic is ready to buy me a new car, if he wins the lottery, because he cannot figure it out. I hope you have an answer, because I don’t want to buy a new vehicle just yet.

Answer:

A starting point for diagnosing this sort of a problem is to scan the computer for trouble codes. Assuming you’ve done that and there aren’t any, you need to look at all of the possible causes from the most probable to the least.

You state that “jiggling the relays and the box” leads to the engine starting most of the time. That certainly implies that there’s a poor electrical connection so I’d very carefully examine all wires and connections that relate to the relays and box. Also, make sure all ground connections are good.

It is possible that all connections are fine and one of the relays is still not working properly all of the time. Specifically, intermittent failure of the fuel pump relay would cause the seemingly random pattern of the engine failing to start and run that you’re experiencing.

Others have suffered with this difficult to-diagnose problem. You mention that you’ve “swapped relays” but don’t elaborate upon which relays you’ve swapped. One way to combat this is by mounting a “spare” fuel pump relay and plugging into it when the engine refuses to start. Assuming it works, you can also temporarily “borrow” the air conditioning

relay to power the fuel pump when the engine won’t run. If switching relays, whether to a spare or to the air conditioning relay, fixes the problem then you know the fuel pump relay is cutting in and out.