The blazer would not start with no codes I did a fuel pressure test 60 psi with key on hooked a timing light up with no success so I started with the cpk sensor after I replaced and did a relearn ran like a champ for a week then went out to start crank but no fire this time it gave the crankshaft position sensor which pissed me off obviously left it sit for 3 days then went out and tried it for ****s a giggles started right up no code no misfire nothing drove it around the block I am nervous to take it to work to then have it happen again and have to pay for a tow anyone know what the issue is if any or is this normal my code tool does not have a relearn feature so I did the 10min key on then off for 30 sec 3 cycles of that. so I don't know if that has anything to do with it or what any help is much appreciated

 

60psi fuel pressure tells us nothing. We need the results from 4 different tests to analyze the fuel delivery system. This link explains: https://blazerforum.com/forum/2nd-ge...eakdown-88305/


The crankshaft position sensor relearn must be done if/when the sensor is moved, removed, replaced or disturbed. It requires a scan tool capable of initiating the relearn. The el cheapo $500 jobbies won't do it. Cycling the ignition, disconnecting the battery, clearing DTC's, etc, will not do it either.


Fuel delivery system problems will not set codes. If the crankshaft position sensor loses voltage on the purple wire, there will be no spark, and no codes. When the engine will not start, you need to determine if the problem is a lack of fuel, or a lack of spark.