Hi all, I've posted this problem on the K100 Forum. Got some good assistance there that helped me diagnose the problem (in part) but haven't solved the problem, so am seeking additional help.
I'm doing a cafe conversion to my 85 K100RT. Bike has 87k miles on it. It was starting and running fine. Then I took the tank off to paint it. I put the tank back on and the bike wouldn't start. Befor this, I have never had any sort of problem--electrical or mechanical with the bike.
I've ruled out fuel issues: starter is working, fuel filter is clear, have fuel at the rail, etc.
The problem is electrical. I have spark. But, I've found that the electrical leads that plug into the fuel injectors are not firing properly. I hooked up a LED test light to them, bridging the 2 female sockets in the plug. When I press the starter, I get a blip of light. Then nothing when I hold the starter, then another blip of light when I release the starter. It is my understanding that what I should be seeing is a very quickly pulsing light when I do this. I've also pulled the injectors out of the bike and cranked the starter with the injectors out. This confirmed what I was seeing with the LED tester--I got one small sput of fuel through the injectors when I released the starter button.
As I understand it, the way the injector electrical works is that there is supposed to be constant 12v to one side and that the other side switches to ground to create the pulse needed to operate the injector (operating an electromagnet to open and close the needle valve in the injector to squirt the fuel). I measured for voltage at the injector plug and it seems to say about 24 or 25 volts on one side and nothing on the other side. I'm not that good with electroinics so maybe I have my multimeter set incorrectly, but it does seem odd that the voltage appears to be double what it should be.
It was suggested on the K100 Forum that I had a bad or weak ground somewhere that was resulting in the ground at the injector plug not switching on as it is supposed to. So, I have cleaned all the under tank electrial contacts, main ground, and the plug to the fuel injection unit/computer under the seat. I used deoxit to clean. Mostly I just opened the various plugs and sprayed it in. For the main ground, I took that apart, clkeaned all contacts with 220 sand paper, sprayed with deoxit and then put it back together. Before doing this cleaning, I was getting no light on my LED tester and no spirt of fuel from the injectors when letting off the starter. I'm wondering if I need to do better at cleaning the connections?
I've also tested a few other things, all to no avail: air flow meter seems to be OK, I tried starting with the idle postiion switch unplugged. I checked that my coils are good by testing resistance between pins 9 and 12 at the injection control unit. I haven't tested the Hall sensors (but figured this isn't the problem because I have spark--though I'm open to being corrected if I am misunderstanding this). I haven't checked the water temp sensor. Should I?
I'm at a loss about what to do now. Would greatly appreciate all help and ideas. Thanks!
