Help! changed heater core, now won't turn over

Ok...had a friend of the family change my heater core at his shop, now the truck won't turn over to start. He said that he can hear the fuel pump when he turns the key, but no turn over. I wasn't there when he changed it out. Anybody have any ideas on what might cause this? It's a '96 LS 4WD. Any help would be greatly appreciated. Thanks.

Ok...had a friend of the family change my heater core at his shop, now the truck won't turn over to start. He said that he can hear the fuel pump when he turns the key, but no turn over. I wasn't there when he changed it out. Anybody have any ideas on what might cause this? It's a '96 LS 4WD. Any help would be greatly appreciated. Thanks.

is the starter cranking? if not then its probably a problem with the ignition switch because the heatercore is behind the dash board

Did anything come loose. Don't the heater core hoses come through the firewall right next to the distributor. Maybe the wire from the coil to the distributor came loose. I got a 98 and figure your distributor should be in the same place. Also, maybe the distributor got wet and you have moisture in the cap.

Wont turn over as in NO reehh , reeeh , reeh . No clicks . Is it posible that the battery was not connected first and the interior lights ran the battery down . It happened to me . Not familiar with the replacement on blazers ,But on a jeep you have to remove the whole dash (door to door). Loosening the steering column in the process . Grounds and harnesses could be effected if this was the same R&R . Rob

Are all electrical harnesses connected? One time I left that little engine bay light harness unplugged and my truck wouldn't start. Took me like 5 minutes of staring to figure it out.. :lol:

Are the dash lights coming on? Do you know that you have spark? srbianats may be right in suggesting you could have gotten some moisture in your distributor cap.