Use an ohmeter, I guess you don't have one. Fuel pressure should hold for longer than you are saying.

 

yes, i have one. it came out to be 1620 i believe
and i know it should hold longer, but ive read something about a bad sensor could cause that?

 

also note that everything was running fine before i pulled the engine apart. the reason for me replacing the crankshaft and oil pump is because my oil pressure droped to 2 while i was driving, and i also had a knock, which was spun bearings

 

im back to the crank sensor. it reads 5v when the engine is not being cranked. for about the 1st second of cranking it averaged .2v. then 0v. is there a way to find out what the spacing's supposed to be between the sensor and the pickup.?

 

1620 ohms sounds very high, that will affect the amplitude to the pcm. Do you have a meter that will read hertz? I don't know the spacing on the crank gear the pickup is reading. The voltage you state is looking at cranking with a digital meter, does your meter have an analog bar?

 

thank you for all your help, i didnt do those last tests that you mentioned. but i got my truck to start. its an odd thing... what happened was, i swapped my not working crank sensor with another vehicle that was running. and immediately after, with no further modifications. both vechiles started just fine.