ok so to explain my 2001 blazer would not start replaced the crankshaft sensor and it fired right up ran 20min shut it off then it went back to not starting turns over fine before but now it turns over added by a loud knock and will not start please help need to fix asap don't have the money for a shop please don't suggest it i've heard that all day thank you

ok so to explain my 2001 blazer would not start replaced the crankshaft sensor and it fired right up ran 20min shut it off then it went back to not starting turns over fine before but now it turns over added by a loud knock and will not start please help need to fix asap don't have the money for a shop please don't suggest it i've heard that all day thank you and just to add the new
crankshaft sensor came with 2 rings my blazer had none so did not add none

did you inspect the connector real good/ clean the pins/ look at the wires they go up by the manifold and can short out there. some cars need whats called a crank relearn by a higher end scanner, if the pcm, crank sensor or a few other things are replaced. some do some dont probably depends how close the new one is to the original. but i would lean more toward the wires or connector by how it started and now wont

How do you know it was the crankshaft sensor? The number one reason a Blazer doesn't start is a failing fuel pump, number two reason is the ignition switch. The crankshaft sensors is not a typical fail item on the Blazer with the 4.3L

there should have been a note with the rings mike the old sensor and new difference between old and newcould cause the new to come in contact with reluctor should have aproximate 30 ths clearence ifnew shows signs of rubbing may have done damage to reluctorwitch will mean replacing timming chain cover as not recomended to reuse will be hard to to reluctor damage with out removing wnile off check timming chainif high milage may need replace hope this sheds some light jimjo hand

This is over a year old, please pay mind to the dates of these threads.