93 transport-no start-but cranks

I have a 93 transport 3.8. no fire replaced with a new crank sensor. tried a used ign module. still no fire. can someone help. there is fuel. pressure is good. what does a knock sensor do.

ALthough a lot of wires connect to and from the ignition control module, several wires - like from sensors - just use it as a tie point and in fact go to the ECM.
THe knock sensor is not involved in your problem: it just causes ingition to retard when engine knocking is detected.
You did right suspecting crank sensor, it is the culprit in most cases...but then, have you read any error codes from the "check engine" diagnostic light?
First thing you should do is read error codes.:
Reading the codes with OBD1 is simple:
Locate the diagnostic plug under the dashboard
www.avigex.ca/xport/plug.jpg
jump connectors a to B with a paperclip or small wire
turn key on
the check engine light will flash code 12 - one then 2 short flashes, repeats 3 times, (this indicates the computer is in diagnostic mode) and then any stored code will come, like 34 is 3 flashes then 4 and each code is repeated a few times (have paper and pencil handy) then when finished it repeats code 12 and goes around again.
COdes are here:
www.avigex.ca/xport/3800codes.jpg

codes are 34,42 and 43. what should i do. aren't 42 and 43 caused by no start.

42 (ignition control problem) is signal of a problem
34 (MAF) and 43 (knocksensor) would manifest only once engine is running: problem with MAF would have to be taken care of later cause it may induce stalling/surging and poor acceleration.
CHeck this out
www.avigex.ca/xport/dtc42.jpg
Do you confirm you have removed one spark plug wire and installed another spark plug on it so you can look for the spark while starting and confirm there is no spark at all?

I guess the "check engine light" is on all the time....

ALso since you have changed the crank sensor, DTC42 might have been there before. TO be sure, you would have to disconnect the battery for 10 minutes to clear all codes, and see if they reappear (specially 42) after cranking the engine a few times. 34 and 43 will probably not come back before engine actually runs.

I Have Power When I Crank Then It Goes Off. At The P Pin On The Module Connecter Is This Any Help.

I understand you have 12 V at pin P while you have the starter ON and then.(???? what is "then"..when you release the ignition key from the start position?) you loose the 12 V?....
THis same 12V also drives the fuel pump.
How about fuses: 20A in line fuse under the hood behind right hand headlamp - (mmm...fuel pump would not work!!!??)
15A ignition fuse in the CONVENIENCE CENTER (under glove box)
www.avigex.ca/xport/convenience_center.jpg
...well not directly related.....

THen...I'd be worried about the ignition switch itself....!

I'd like to have more details about this 12V / no 12V on pin P. IN fact, do you mean you have sparks when it cranks then no spark after key is returned to "run" ? ..sorry I'm a little confused.......

i have spark as soon as i crank, then it turns off. a few seconds later. almost like the fuel pump when you turn the ignition to run position it pressurizes then turns off.

..OK ..weird.....I have 6 pages in the "book" . I will progressively scan them and ADD links IN THIS POST to avoid clutter...Of course, there is no direct reference to a condition where you have spark initially then none aftewards...however, I would lean on the side of cam sensor problem.....but that should pop a code 41.....
www.avigex.ca/xport/dtc41.jpg
www.avigex.ca/xport/dtc41procedure.jpg
Other than that, I'd try a test with another ECM unit..just to clear that idea, because I'm reluctant to think this can be the CAUSE...these units are really sturdy and are replaced most of the time in desparate situations where they will find in last resort that there was ALSO (!!!) something else awry..... but, at least, testing with a spare unit clears the mind.
BUT...it just comes back to my mind.....if you loose supply on that pin P..this is uncontrolled...just plain 12V straight wired through the ignition switch to that circuit ..so all the fuss about computer and sensors is out of that game....need to confirm that..and if it keeps cranking, then the juice reaches the ignition switch: next drawing: 12v to starter is on one gang, and 12V to inj fuse (pump, ignition module) is on another gang....I'm back to the ignition switch if confirmed.......
www.avigex.ca/xport/powerdistribution.jpg

I'm just thinking of something else....but this would be right if you had spark...anyway, just in case
I happen to mave modified my temperature sender to make the computer "think" my engine is warmer than real. THis is a switcheable mod because if I let the mod "on" and try starting when outside temperature is cold, the false temperature sent to computer makes it lean the mixture so much that it will not start...so I have to return it to "normal" and then 30 seconds after being started. I switch to high temp reading and this translates in VERY significant fuel savings in winter.
THis to explain that if by "chance" your temperature sender is gone wild, it may send a false reading and then no start. Just disconnect it (near the thermostat..this is a 2 wire sensor.Beware: there are 2 coolant sensors: one for the indicator -single wire - and one for the ECM - 2 wires) and give it a try...not an expensive test.....

i have replaced temp sensor and also ignition module. same result no start

where would i find the 20a inj fuse more or less.

THe 20A INJ fuse is hanging near the right headlamp, close to the bank of relays. www.avigex.ca/xport/fuelinject.jpg
you would have no fuel pressure if it was blown.
You had started something interesting speaking about voltage at pin P....As I understood, the engine fires up during the "start" sequence but as soon as you release the key to the run position, it stops. Is this interpretation correct? If so, it would point to the ignition switch and some "bypass" can be tried to confirm that option....do not neglect the clues you have already found...........

Try un plugging the MAF sensor
I read that in another post some where
might help......

Dave I had same problem checked it by jumping across pink and red wire going to ignition switch.After doing this car cranked and ran, thus i replaced ignition switch. Problem was car would turn over, lights , gauges everything worked, but wou,d not start. Replacing ignition switch solved problem.