If that's the problem....then why would it eventually fire up and start?
And then keep starting for the rest of the day after it warmed up?
Because the way the system works, and this is pretty standard anymore is that the fuel injectors won't fire unless and until the crankshaft position sensor sends a go signal to the engine computer and the engine computer relays that signal to the fuel injectors.
So what happens is that when a CPS starts failing it begins to randomly not send the appropriate signal and so the vehicle will crank but not turn over. Eventually it will not send the signal at all.
His technician can easily verify this either with a scanner by simply going into the datastream and checking the CPS voltate or by using a multimeter to manually test the voltage at the CPS. It' a simple 2 wire sensor. One wire has a 5V reference and is always hot , the other is the wire that signals the ECU that engine has been cranked over, it should have around 5 volts when cranking , if it's < 3.6V the sensor is definitely bad.
99 out of 100 times it is this sensor. No guarantees diagnosing it over the internet. But that' my thought.
I'm an electronic technician by trade and have my own digital multi-meter. Is it something I can check? If so, where is it located and which wires should I check?
Yes , you could test it and probably even change it if need be by yourself.
The crankshaft position sensor is located on the lower right front of the engine. Down by the crankshaft pulley itself.
here is a generic sensor, they all look similar.
there are two wires. Can't remember for sure, but I think they are Dark Blue and the other is Gray. I can look it up if you need me to.
The Gray I believe is the reference wire. Should have 5V at all times, the other is the signal that should put out around 5V when the engine is cranked.
If it needs to be changed, its a simple unplug electrical connector, remove two 10mm bolts and gently pry sensor out of engine.
Reverse to install, but be very careful not to scuff the end of the sensor. There may be a felt pad on the end of it, do NOT remove that pad, it is a spacer that must be there if it came from the factory with one.
If you do it yourself be aware that for the first 20 miles or so after replacement the truck will drive like shit until the computer can do a relearn.
I can't promise anything , I mean I'm diagnosing without even seeing the car you know, but I'm fairly confident it is the Crankshaft sensor.