I've got a 1995 GM Suburban with the 5.7 engine that refuses to start when it is below 40 degrees outside temp. If I use the block heater, it will start fine but won't even pop if it is not plugged in overnight. I have had it analyzed at a local shop and they couldn't come up with anything. They could not get any codes to come up on their machine. Any ideas as to what could be causing this. It has been a good truck, but I can't keep it around if this keeps up.

Thanks for any help

Jeff Welte
Rockford, IL