1998 GMC Sierra Cranks attempts to but no start

Yes the fuel pressure is normal, should be 60-66psi. It is normal for the pressure to hold with the key off. A rule of thumb is it should not bleed down any more than 5psi every 20 min. So this is normal and it shows the injectors are not bleeding down. As far as checking things these are some things to check:A loose CMP sensor causing a variance in the sensor signal

"Â Excessive free play in the timing chain and gear assembly

"Â Incorrectly installed distributor - 1 tooth off in either advance or retard positions

"Â A loose distributor rotor on the distributor shaft

"Â A loose or missing distributor hold down bolt

was the distrubutor ever taken out? A bad crankshaft pos sensor can cause this. I've also had a few with the distributor broken and loose inside the shaft. Might want to pull the cap and move the rotor back/fourth and see if the dis moves excessively. Found a couple broken distributors. Post back with what you find and will advise from there.

Yes a bad crank pos sensor would cause no spark, it might not throw a code. Looking at the scematic the crank pos sensor, it gets battery voltage from the pink wire at the under hood fuse block and goes directly to the crank sensor. The crank sen is a hall effect sensor which means it has an internal ground if there is a problem and the crank pos sensor dosen't close to complete the circuit it will not run, also battery voltage runs through the crank pos sensor and then to the cam pos sensor then to the ICM, which would cause a no spark condition. Also you can monitor crank rpm's with a scan tool, when you crank it see if you have any RPM's on either sensor, might tell you if there is a problem. Follow this first and post back with what you find and will help.