This one does engage the starter and the engine spins as it should but the truck doesn't start. The technical term for that is a crank/no start condition. The engine cranking properly means we don't have to consider any starter or battery related issues and can consider those as tested and passed. This is when some might say I think its the fuel pump, or similar guess. When you are the one supposed to find and repair you can't just guess and try that. I don't do checks in a particular order, I work with the truck. It isn't the fuel pump. The fuel pressure is easy to test on this, and within specs.
We can move on. Just because I have primary fuel pressure in the rail does not show that I have secondary fuel delivery via the fuel injectors which are electrically operated. The quick test for that would be a noid light to let me know if the injectors are getting power and ground signal during cranking. The light simply plugs into the injector connector and will flash as the injector pulse is present if that system is working.
We have cranking, primary and secondary fuel delivery. We are going to look for secondary ignition (spark) from the coil next. The coil is very easy to access on this truck and we want to look at the connection and ignition coil tower for obvious problems before beginning the spark output test. I see the problem. Rodent damage to the ignition coil wiring harness.
I repaired the wire damage and we are road ready! Diagnostics are about understanding how the system works and forming a logical testing sequence to gather the information you need as quickly as is possible. There are systems that are very difficult to diagnose due to the complexity of the system as designed and occasionally due to the atypical cause of the problem but the same method will apply, understand the system, test logically. You are actually more looking to put aside what will not be the problem so you can more quickly find what is the problem. I call it the Cat in the Hat method. To paraphrase, the way to find the problem is to find what isn't the problem.
See ya next time!
Kenny@ggauto.repair
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