1990 K75
Seems the fuel injectors aren't working correctly. Bike will start using starting fluid but wont stay running. I took the fuel rail and injectors off to test and the only time fuel sprays is when the starter button is released and only 1 shot. Seems backwards to me.
Any suggestions where to start would be helpful.

You don't want the injectors to keep spraying fuel until the bike starts and can burn the fuel.

Send them to Mr. Injector while you have them out.

http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/fis/fis.htm

Retro Rebuilds wrote: I took the fuel rail and injectors off to test and the only time fuel sprays is when the starter button is released and only 1 shot.

If the starter relay, fuel injection relay and Hall sensor are operating correctly, when the starter button is pressed the starter cranks, the Hall sensor is energized, the fuel pump is energized, and the injectors should start spraying fuel. If the engine starts, the Hall sensor continues to energize the fuel pump and the injectors when the button is released. If the engine doesn't start, the fuel system shuts down after the button is released. You'll hear the fuel pump run for a second or two then stillness and a sense of longing will likely become oppressive. This is also when repeated unsuccessful attempts to start the engine might lead to howling at the moon.

Start by viewing the various troubleshooting schematics and system descriptions throughout this document from the Tech Pages within the Portal. Systematically troubleshoot step-by-step using the guide. Avoid attempting repair-by-part-replacement unless testing confirms malfunction; however, having the injectors from a neglected engine reconditioned by competent technicians is a good move.

What type of modifications have been done to this moto? What is its history? Please put the moto's model and year in the Signature section of your Profile so it will show up along with every post you make and readers will know what you've got. You'll probably be making a few more posts.  

If the injectors are squirting when you push the starter button, then they are likely working. From what I've read the K75's are a bit more cold blooded than the K100 and need some choke to start.  In lieu of the choke you can also give it a bit of throttle when you are trying to start as all the choke ( so called on these bikes ) does is lift the throttle rail. You could try setting the air screws ( brass screws ) at 1/1/2 turns out from stop, to see if that helps. You'll then need to use some sync gauges to get them right. Leave the screws with the lock nut alone. They are another can of worms that you can get into and takes a bit of work to get them right.

I replaced the injectors in my K100 with a set of reconditioned ones from Mr. Injector. The engine runs much smoother than with the old injectors. It was cheaper for me to just get them than to mess around with getting the old ones reconditioned.  They sell the reconditioned stock Bosch injectors for the K 75/K100 and the prices are reasonable.

So I check all the grounds and connections and really didnt see anything wrong. Then it started and ran just fine without issues. Went out the next day and now I dont hear the fuel pump coming on, I tested the connection and no power to the pump, no power at the fuse (second from bottom) when the starter button pressed. I went back through all the ground and connections but nothing. Could this be the Hail Sensor or the FI relay?

> no power at the fuse (second from bottom)

Check the fuse with a multimeter. Blade fuses can pop without you being able to see anything visually.

2nd that comment - 

Pull the fuse(s) and properly check

Replace if in doubt with new

They can give inconsistent readings as they age

De Oxit (or contact clean) the connections

GF