Fuel Pressure Regulator or Crankshaft Sensor?
 

If the CRANKSHAFT sensor is bad will the engine (3400cc) start? I know the CAMSHAFT sensor can be disconnected and the engine runs, I am going to replace the CRANKSHAFT sensor for the third time and this new one is going to be a GM unit and hopefully the money light will go away..
regarding the FUEL PRESSURE sensor can someone explain what it does and what actuates it? There is a vacuum line that goes to it.
My problem is the starting of the engine which is hit or miss, sometimes it will start on it's own and other times it needes a sniff of either and then it will run until the key is turned off. If I have no vacuum at the FPReg will fuel still flow to the injectors? When the engine goes into it's no start mode it does have spark and the injectors are working, I must remove the air cleaner and squirt a shot of either then turn the key and the engine is running until I shut it off. I at one time thiught it was the pass key but I have rulled that out Thanks for the help in advance.

some details would be great, please.
year? trouble codes?

yep some info would be good as there are different designs.

for what i think you have....the fpr is a diaphragm and calibrated spring. if keeps the fuel pressure at a set pressure and sends excess back to the tank. the vacuum line applies vac to the diaphragm. when vac is there the pressure is lower...when vac is lost the pressure is increased. so with vac maybe 35 psi, without 45psi. the engine needs more fuel pressure on hard acceleration. vacuum is low when the throttle is opened.

no crankshaft signal = no injector pulse and no spark= crank no start.
if u have codes write them down...clear all...set what resets and post back

2003 Venture 3400 base, A/C-PWR WIN-PWR BRKS-AUTOMATIC 2 wheel drive.The code is for the crank sensor my son can clear ir but it comes right back PO335, what I am trying to figure out is why the engine will not start when it has spark and inj are working I also have fuel pressure with key on I have replaced the fuel pump, filter and the pressure reg 2 times and crank sensor 2 times, here is the kicker when it does not start I can give it a shot of either and it will start and run every time. I can come out and try to start the car with no additives and it might start also I should say that once the car is running I can turn it off and restart with no problem.
Pass Lock is not the problem. Using timing light to verify spark and noid light to determine inj operation.

starting after a shot of ether suggests a fuel problem. when the fault is active check the fuel pressure and monitor the guage for pressure leakdown.

here are some tests to diag the code
1. Verify that the crank pulley/reluctor is all the way on.

2. Test voltage at the 24X sensor, Light Green to the Yellow/Black, back probing with a Digital Volt Ohm Meter (DVOM), engine cranking.

3. Should have over 9v.

4. Test for a 0-12v square wave pulse on the Light Blue/Black wire from the CKP sensor to the PCM, blue connector, pin 9.

5. Verify the Light Blue/Black wire, circuit #647. Test the wire for continuity from end to end and verify that the wire indicates open from one end to ground.

Have you checked bulletins for your vehicle?

http://ww2.justanswer.com/uploads/Sp...17_0834723.pdf

I do not think fuel is my problem as I have a new pump, filter and I am getting close to 50 psi fuel pressure, I just do not get it it has everything in needs to start spark, injectors are firing and i have fuel pressure. My son has some pretty fancy tools but his reader is limited due to the age of this engine and or car. I will keep you up to date but I need to get back to work on my 1950 Prefect I am getting older and I want to be able to drive the car that I remember as a kid.

what do you think ether does? clear a possible flood condition is one possibility. that's why i suggested you monitor for fuel leakdown. fuel leakdown would cause a hard start after a hot soak.

fuel-pressure-regulator-crankshaft-sensor
 

Well the verdict is in it was neither what it was is rotten wire, removed old senser and that is when the wiring fell apart problem solved but now I have another problem and this one might be the junkyard whistle, seems the dampner nut might have bad threads I cannot get it tight onto the dampner when my air impact gives up I can still spin the washer. and the darn bolt will not back out, sometimes you have to throw in the towel.

But back to your original question, yes the engine can still start if the sensor is faulty. I had that problem, it started okay but the engine ran worse as it got hot, particularly under load.