Won't start
 

HI,

I have a 2002 f350 with the 7.3, it will not start the first time each day without being plugged in to warm the block. I am in Louisiana and some days when I try to start it in the afternoon it is around 90 degrees. It will always start after it is plugged in for about an hour, but runs terrible until it is warmed-up. I replaced the glow plug relay and still won't start. Have checked the relay with a meter and it cycles off about 30 seconds after you turn the ign. on. I have another f350 with a bad glow plug relay and you never a problem until the winter. Once the engine is warmed-up, there are no other problems and it starts and runs fine.

Thanks for any advice,
Charlie

Have you load tested the batteries?