My unit is a new to me 4d55 swapped into a former gas '91 Isuzu pickup. Will not start in the morning without plugging in the block heater. Fires right up if I do. Temperatures here are 40 degrees and less this time of year. I have worked thru many issues successfully, but this one has me stumped. I have 400 lbs compression each cylinder, am getting fuel, have a manual glow plug switch (Ford type solenoid) using new 12 volt NGK glow plugs. It does not seem to matter how long I run the glow plugs (and yes there is power to them) it will not fire. I'm afraid of a really cold day chilling off the motor and being stuck somewhere without a plug-in for the block heater. Any suggestions anyone?