So by complete accident I hooked up the battery backwards and tried to start it. Now I'm getting now spark, all the dash lights are on and gauges will not work. What would I need to start checking to get this thing going 1988 fc convertible. N/a 6port.

 

You'll need to check every fuse and hope you didn't blow out the CPU. And get some paint and paint the battery positive terminal indicator and maybe some red tape to mark the positive battery cable.

 

Check the engine bay Main fuse to see it it blown( it BOLTS In,so you can't just pull it out like the other 20 and 40 amps fuses in that fuse block)
also check the illumination fuse and room fuse..and any other fuses that may think can hinder starting(sorry I can't think of that damn fuse..lol!)
You can get the Fuse box diagram and the Names/locations of those (the fuse block under the dash,driver's side) in the FREQUENTLY ASKED QUESTIONS for SEC GEN (New member section Sticky)

 

Remember the next time that the NEGATIVE Battery cable is the one with the Yellow Stripe on it!
Or as Kansas said just wrap a piece of RED around the POS and BLACK on the NEG cable and you should be fine..no more mix up.
(trust me you are not the first one to do this.!)

 

15 amp engine fuse.

 

I did the same thing, i blew the main fuse under the hood, and the compartment fuse inside, luckily thats all it did

 

I did check the main fuse. Let me give a little more information. Car cranks without a problem. Have spark as well. Checked main relay and open circuit relay. Both ohmed out good. Problem I still have is all the notification lights are on and gauges still are not working. Also on a side not, is 8v at the fuel pump normal? Used a power probe to trigger it and only 8v were being used. Still will not kick on with the key in start position.

 

8 volts is rather normal for w/key to start there is a lot of amperage used by the starter.

The gauges rely on the meter fuse (except the speedometer).

The idiot lights turn on w/key to on but engine not running.

Try 1-2 seconds of starter fluid and see if that starts the engine briefly (engine could just be flooded).