Bike: CBR 600 FL 1990

I've had a read through the forums about the no spark issue on many of these bikes and found some things to try out, so thank you.

Basically I have no spark and no fuel. so ran through all the test on the ignition system. Coils reading where a bit high:

Power to both coils.
coil primary (manual 2.5-3.1Ω ) getting 3.3 (1-4) and 3.9 (2-3) Ω
coil secondary (htleads) manual: 21-25 kΩ getting nothing.
coil secondary (htleads removed) manual: 11-15 kΩ getting 14.63 kΩ on both.
pulse generator manual 450-550 Ω getting 520 and 526Ω

So fitted a new loom and 20 minutes later I got a spark on 2-3, tried 1-4 still no spark. moved the power cables from 2-3 coil to 1-4 coil and got spark on 1-4.

So took a power reading on 1-4's leads and getting 12.68 with ignition on. So traced the wires back and everything is as it should be.

Decided to check out the fuel pump and nothing, so connected it to the battery work's fine. Ordered a relay from ebay and still nothing so can't rule out its another duff fuel cutoff relay as the pumps no getting power.

Figuring I'm looking at either a duff Spark unit or a duff fuel cutoff relay basically I'd rather try the cheapest first. so question is would it be possible for the relay to stop the coil from sparking?

 

No, but the fuel pump will not run unless it's getting power from the coil.

 

Actually the coils and fuel cut relay both receive power any time the ignition switch is turned on, and from two different circuits. The fuel cut relay closes & sends power to the pump when it receives the ground trigger from the spark unit to the first coil (cylinders 1 & 4). The tach also operates from this same ground trigger circuit.

I would not be concerned about the coil readings being slightly high, as temperature will affect the resistance through the coils. The fuel cut relay and the coil for cyl's 1 & 4 use the same input from the spark unit, so I would suspect either a bad spark unit or bad wiring somewhere between the spark unit & coil.

I would suggest following the service manual procedure for inspecting the spark unit, and make sure you have continuity in the wiring harness on the yellow/blue wire between the spark unit, the primary (1 & 4) coil, and the fuel cut relay before doing anything else. If the spark unit isn't sending out a firing trigger for the primary coil you will not have spark on 1 & 4, the fuel pump will not run, and the tach will not operate.

A very good wiring diagram can be found here: http://img809.imageshack.us/img809/1...colorscopy.jpg courtesy of member Corruptfile

 

Thank you

Thank you TahoeRider

I spent yesterday running over everything in the manual. A mate also gave me some other things to try out and its all pointing to the spark unit not working to coil 1-4.

thank you again to both you guys for the help

 

What I said wasn't wrong. but yes, the fuel pump does receive power when the bike is on, but the fuel pump will not operate until you have spark in the 1,4 coil.

 

I don't intend to start an argument here, and I might be reading your post wrong, but it's the output from the spark unit when the engine is turning over or running that energizes the fuel cut relay to power the pump, operates the tach, and fires the ignition coil for 1&4. Unplug the primary coil & the fuel pump will still run and the engine will still fire on the 2&3 cylinders when it is turned over.

 

nope, your right and I was wrong.