98 5.7 chevy k2500

98 chevy 5.7 vortec. I'm getting a hard start long crank rough idle and once in awhile it will skip at higher rpms. And have no codes! I've replaced plugs wires cap rotor and can sensor. Cleaned mass air flow brand new upper intake no fuel leak in plenum new fuel filter new temp sensor cleaned every ground cleaned egr and crank sensor. I have 2 spare fuel pumps changed it just to see if one was weak and same results. I have been trying to figure out my live data numbers for this truck like what is the correct numbers I'm supposed to be seeing while running. Truck dose run great just the long cranking tells me something isent right this morning was 5 degrees out coldest it's been in awhile and she dident wanna start very goodi have snothet98 sabe truck that will start in a split sec even if its negative 10 out. Truck has 160k plenty of life left in her. Ive been at this truck for 8 months know mechanic says it's fine but never drives it or hooks computer up cuz ye says no check engine light he dnt need to...... needless to say hes not my mechanic anymore I do alot of my own work but when its busy season sometimes I just need it fixed. I have time to work on her becouse she is my maine work horse. What could this be? I'm leaning twords a work distributor gear. I have a brean new but honestly afraid to install I doubt myself sometimes even though I can do it done it on old truck no issues. But what else could it be! I have a scan tool with live data and trying to figure out what my numbers are supposed to look like at idle and under load if I new how to read that I'm sure I could narrow it down more. Thanks in advance. Also jesse
rousseau is my facebook if any want to pm me.

First thing is look at fuel trim numbers along with doing a compression test on each cylinder. If fuelntrim numbers are negative -15 to -25 you have a rich condition. Primary suspect is the spider injection in the lifter vally (under intake plenum) they are known to leak. I would smell oil on dipstick tube and see if it smells like gas. The other thing is sparkplug gap and was it set to specification and ohm test coil primary and secondary to make sure that is within specs if it is on the high end of specs or out of specs i would replace it also ohm test plug wires. Also just because cel is not on doesnt mean there are no codes. So scan it anyway.

If compression test checks out ok, try cycling the key on and off several times before attempting to start your truck, this can prime up a fuel system that has bled down over time. These systems are very sensitive to fuel pressure decay, only a few pounds below spec can result in extended crank times. I have had several 5.7 vortec's pass a key on engine off fuel pressure test but fail while cranking. I have never found a spec for fuel pressure while cranking but I have experienced that if fuel pressure does drop more than 10 PSI during a start attempt there isn't enough pressure to open the injector poppets. Weak fuel pump, pressure regulator and or leaking injector spider, like mentioned in the previous post, could be the cause. Use an accurate fuel pressure gauge to gather your pressure data and post your results.