Hey folks ... just as the title describes, I somehow reversed the polarity of the jumper cables while trying to jumpstart the truck. Stupid, I know. I didn't notice until after trying to start the truck. Needless to say, once I hooked the cables up properly, I could get the truck to turn over, however it just sat there and cranked, never firing. Can you folks give me some ideas of what to test? Obviously everything from the battery to the starter is ok. I'm not sure if the spark plugs aren't sparking, if the fuel injectors aren't injecting, or if a fuse is bad. Please help.

2000 Expedition
5.4L V8

Kyle

 

Straight off, check the 'grey' fuseable links at the starter motor relay at the right/passenger side firewall area.. Most times a reversed polarity will burn the links, give them a 'tug' as well, if the insulation looks to be good.. They can be easily replaced.. Might be a good idea to check all of the fuses for circuit protectionin the battery junction box (BJB), as well as the central junction box (CJB) located in the instrument panel.. More so if it has burned the links, and if it fails to start once repaired...