Done this before, but today, the outside air temp was about 48. Turned on the ignition and waited for the "wait" light to go off. The engined turned over for aobur 3 or 4 seconds beore finally firing. After the truck was warm, it fired in less than a second. It has done this before. If I cycle the heater grid a 2nd time, or if the truck was plugged in, it usually starts right up. But at 48 degrees, I should not have to cycle the heater twice.
Is my heater grid going out?

 

It kinda sounds like a air leak in the fuel system the way you describe it.

Other things that control the Grid heater is IAT (Intake Air Temp) sensor. It might be going bad... Just a wild idea...

 

maybe the grid heater never even came on......check the relay and or soleniods, u can have someone cycle the the heater as u check for voltage on the heater contact points.

 

I'm not sure but it may be that the heater does not opperate until 40 , your truck is newer than what I'm familier with but I had the some symptem and it was the fuel shutoff relay starting go , filed the points , problum gone for 8 mnts now , and the other post about fuel leak is something I've read a lot .