Hi my name's Robin, I spend most of my time in COROWA, on the Murray River, Australia.
Here I have several bikes, including XJ 650 Yamaha x 4,, Triumph TT600, and of course 1986 K100 RT which is my new toy.
The K100 presents a few challenges for me and I have joined the forum for guidance and basically to learn more about them.
My first challenge is the odometer. I managed to get a set of gears and fitted them ok, when I reinstalled it nothing, even the Speedo went.
Pulled it all off and looked at sender unit. Tried the test this form mentioned, Nada.
No the bloody thing turns over and won't start. So time to look for some fault finding flow charts.
All of this is what I enjoy doing.
So hope to meet a few locals with similar interests.
Cheers.

Hi Robin, welcome. 

Unlike a Yammy with a Carby (with air vent in Carby) the brick has a vent in the tank but not the fuel rail, so the fuel in the tank could go stale before the rail. I'm assuming it only ran shortly, before the no start problem, and the bricks been in storage for years before you got it. If so it wants a good look at the fuel system, hopefully it only needs fresh fuel. 

You should hear the fuel pump continue for a second or so after you release the start button. You should see fuel return into the tank with the starter pressed. You should hear a ticking with a screwdriver to the injectors. Remove the fuel filler cap assembly to get to the filter, pump, and a clean. Check the spark plugs for spark and fuel. Check out the fuses. 

For Bert's troubleshooting guide go to the Portal Tab /  K100 Forum Tech Page / I agree / Electrical / Troubleshooting The EFI.

Hi Robin. Welcome to the K100 Forum.
I would agree with Daveyson. Fresh fuel and flush the tank and fuel rail as well. Wouldn't hurt to chuck a little injector cleaner in there as well.
Check that the pump is running when you hit the starter.
Make sure you have a good charge in the battery (13v ±4v) and you're getting a good charge from the alternator (14v ±4v @ 2k rpm). Remove the voltage regulator and clean and inspect the brushes.
Clean all your earth connections. There's a main earthing point under the tank on the frame spar. Earth return on the gearbox. Starter motor earths at the mounting point. Sometimes with the older K-bikes the battery earth cable becomes corroded and frayed.
New spark plugs with the screw on nuts and check the HT leads for corrosion in the plugs and correct impedance.

Once you have this base-line you can start with Bert's trouble shooting flow chart.
Cheers.

Welcome Robin

from a soon-to-be-retired bike enthusiast.

Robin

good luck

Well found a blown fuse, but that didn't solve the problem.
Pulled out the fuel pump. Hooked up jump starter battery, ok.
Hooked it back up to bike wiring, pumped ok when I hit starter.
Made sure the feed hose was clear by disconnecting at fuel rack, ok.
Re installed the pump.
Fired up first click.
All I can suggest is that maybe some small piece of lint seized up the pump, causing fuse to blow.
In the process of removing the pump and putting a jump start power on, the obstruction was obviously dislodged and thrown out.
That's all I can think of as a cause.
Thanks again to all members suggestions, I will go over the rest of the bike now that I have all of the fairing off anyway. Cheers.

Is the inside of the tank nice and clean?  Have you changed the fuel filter?  Are the hoses in the tank in good condition?  What is the condition of the wires going into and in the tank?

Inside was very clean. Wires ok, the feed tube will need replacing, it was a bit spongy at the connection end. Same with fuel filter when I find it.
Everything on this bike is hard to find.

robinvirant wrote: Same with fuel filter when I find it.

It should be in the fuel tank connected by a hose to the fuel pump and to a hose to the delivery port. It's about the size of a 6 ounce can of tomato paste but doesn't have a tomato picture on it.