Hey i have a 94 GMC 6.5 non turbo with 282k kilometers and ever since i bought it it has started poorly. It takes about 5-7 seconds of cranking before it starts, every single time but after that much cranking it fire up beautifully. if you re-start it, hot or cold within 30 seconds to a minute after it has been running it will fire right up. but if it sits for a couple minutes or more it has to crank it's 5-7 before it fires up.... i changed and checked all the glowplugs and it made no difference at all.... the temperature of the air outside has no effect on the starting either nor the temperature of the motor. the glowplugs cycle how they should, around 10 seconds on cold startup an temperature appropriate the rest of the time so i'v pretty much eliminated the glow plugs. i initially thought maybe the lift pumps prime circuit was missing when the key was turned on so the lift pump wasnt engaged untill the OPS sensed oil pressure but read in a thread that it doesnt have a prime circuit in that year. i also did the lift pump tests an theres plenty of pressure. i also tried another Fuel driver and there was also no change... i have no codes but have access to a mac mentor scan tool to read all the parameters if need be. i have no access to a manual to read up on anything so i'm pretty lost at this point so any help at all from anyone would be awesome thanks!