Been having some issues with the truck not starting... dug into a couple problems a couple months ago on another thread, and problems went away for a while but they're back and I'm not sure if it wasn't just coincidence before.

Issue is that at first start in the morning I often will turn the key to start and get nothing. Not even an attempt to start. All radio, lights, headlights, etc work just fine, but no attempt to start.

In order to get the truck to start I have to leave it in key on, engine off for a while and then when I try to crank it, it will start right up. Length of time left in KOEO seems to be dependent upon exterior ambient temperatures.

For example, if the sun's been up for a while and shining on the truck it doesn't happen at all (Saturday and Sunday), but if I'm leaving for work at 7am and the sun hasn't hit the truck yet, it happens, but generally starts within a few seconds. Yesterday we got a Florida "cold snap" and the temps dropped all the way down to 58-60 overnight (as a Colorado boy it's time to crack out the flip-flops at 60!!), and it took a solid five minutes of sitting in KOEO yesterday to start. Same thing this morning.

I'm used to having difficulty starting a diesel in REALLY cold weather (not 60 degrees, LOL!) but I've never heard of cold or "cool" weather affecting a gas-guzzler... this truck has the 5.4L Triton V8. Any ideas of where to start troubleshooting this?

 

The ECM (engine computer) is on it's way out. Leaving the key on warms the circuitry just enough to make it work. Another way to test this is the next time it won't start, turn the key off and use a hair dryer to warm up the ECM. If it fires right up after you've warmed it then you've confirmed the problem is the ECM.

 

Thanks. The Ford dealership wanted to replace it about six months ago when I had it in for plugs and wires but I said no... guess I should have said yes!

 

Tgis could actually be as simple as a bad solder joint or similar, if you're feeling adventurous, you could open the ECM and check all solder joints withba magnifying glass, resolder if you find a cracked one. This is assuming that you have aome basic solder skills of course, dont attempt it if not. Another option is to send the ECM to a repair shop instead of buying a new at the dealer

 

Isn't it filled with resin?

 

I am not sure actually, haven't taken the PCM apart before. I doubt it's filled with resin, but the PCB is probably coated with some material for "weather proofing" it. I could be wrong though