I would check a lot of simple, zero cost items first. Ones that you did not mention checking in your post.
Check all the battery and ground connections. Inspect the cap and rotor for any damage or near physical failure. Excessive, play in the distributor shaft. Check the high voltage wires in the dark for leaks to ground. And check for any loose vacuum lines, or damaged wires. I would spend a few hours going over it and checking these and the electrical conectors before I tackled replacing the crank sensor as a maybe it's this or that part. Especially if you are short on funds.
That said, 5-90 is probably right, but there are other possible causes, especially in the high volatge areas like oil suddenly leaking into the rotor area under the cap. That is one where you can see the problem visually before buying any parts and going the trial and error method.
5-90? Has anyone ever miss diagnosed a bad ground as a bad or failing crank sensor? Since the crank sensor is such a low current, low voltage device, I can't help but think a lot of marginal or just weak CPS sensors get replaced due to poor grounds? This question, thought, is based on my recent self re-education as to the detrimental effects of few ohms here and there of resistance in a very low volatge computer control system like Renix. I am thinking a 20 to 30 ohm wiring system loss (added resistance) could be just enough to make a CPS look bad?
What thinks Ye?
