2003 Chevrolet Express 1500. Truck has experienced several instances of failures to start and is currently down for the same reason. Details of this incidence are: approximately 24 hours after having been run, the truck failed to start. Cranking was normal; no indication that the engine was firing at all. Air cleaner was removed with no change. Starting fluid was introduced into the air cleaner body (filter removed), again, with no change. Plugs and wires were replaced with new; no improvement. Coil was replaced but no change. Rotor and cap were replaced; truck fired but would not run more than a few seconds. MAP was replaced, again, truck fired but would not run. The old plugs had been used for approximately 20K miles, and all except one had electrode damage that made the electrodes appear as if they were needle shaped, and the gaps on all were much larger than would be expected. There was some carbon fouling on all plugs. When first started after all the parts except the MAP were installed, there was arcing detected at the coil high voltage connection. The connection was removed and the male and female connectors were cleaned; silicone was applied to the male connection and the arcing stopped. All other HV connections were checked for arcing and none was found. The run failure continued through all of these steps, and it only began to fire after replacement of all the HV components. The battery was disconnected when the coil was replaced, and it was reconnected immediately after the new coil was installed. I am out of places to look. Any suggestions?
I need to ask what size engine does your truck have and how many miles are on it?
Was the check engine light on before you started to do all this work?
Did you check for any trouble codes in the computer memory with a scanner or code reader? If any trouble codes come up, repair them and go on from there.
You said you replaced the coil, was it new? There shouldn't be any arcing at the coil if it was new and the wires are new. Make sure there is no arcing, if it is arcing you will get spark at the coil tower but it won't get to the plugs because it is going to ground. Make sure you have spark at the plug wires at each spark plug.
When you replaced the wires, cap and rotor, did you check to see if the firing order was correct.
Was the fuel pressure checked and if it was what was it?
A simple test you can do is take the oxygen sensor out of the exhaust pipe and try to start the engine. The reason for this is if the exhaust is restricted the removal of the sensor will relieve any pressure in the exhaust system. With the pressure released the engine may be able to start if this is the problem.
Depending on the mileage, performing a compression test on all cylinders can help diagnosis a faulty mechanical condition. The valve timing being off can be caused by a timing belt or chain skipping a tooth on the gear throwing the valve timing off and causing a no start / hard start condition.
Try to get the answers to some of these suggestions and get back to me when you can. We can go on from there.