Having a problem with my 2000 CBR 600 F4 and need some help.

I parked my perfectly running bike at the end of June for a week, then when I took it out to ride it the engine would not start. Bike cranks over normally and I can hear the fuel pump prime, but no start or even a chug from the engine. I checked the fuel, and it is fresh and about half a tank. I checked for fuel in each carburetor by draining a little fuel from each float bowl and there is gas in each. When I spray carb cleaner in the carbs, still no combustion at all from the cranking engine.

Checks performed:

Battery is good – New in 2019. Tried cranking with a start assist booster and no change (no sound of firing). Battery at rest and charged, sits at 13 VDC.
Fuel level – Good, and recently filled.
Fuel pump – Sounds to be priming as normal on start-up.
Kill switch – Set at engine run position.
Fuses – Check of all fuses located under the seat and all were good.
Kick stand switch – No previous issues. Tried to start with kick stand down and up and no change.
Spark check – Removed one spark plug and it looked fine. Connected coil to plug and rested plug on engine case and cranked over looking for spark and nothing. Held plug in hand during cranking and felt nothing.

Conclusion: CBR has no spark.

Suspect Causes to be Confirmed:

ECU could be faulted.

Ignition Zener Diode could be faulted. The diode reported to be a reliability issue. I am only getting 7.71 VDC from the “pink wire” from my ignition to the ECU and I believe the voltage should be 9 VDC.

Tip over switch could be faulted. (Don’t think this is an issue as fuel pump still has power and the 2000 model of CBR may not have this safety switch.)

Another electrical fault holding back spark. Peak voltage testing of ignition components may find the cause of this problem but I don't own or have access to a peak voltage adapter for my meter.

I forced / supplied 9 VDC into the “pink wire” at the ICM terminal from a power supply and the engine backfired then started. I allowed the engine to warm up, removed the forced power and took a 5 mile ride and everything felt to be working normally. A day later, I started the bike (without forced 9 VDC power) and took it for a ride and within half a mile, the engine stopped, similar to using the kill switch then it would not start again (cranks fine but no firing like no spark).

I ordered a replacement Zener Diode because when testing the pink wire at the base of the ignition, I was getting various voltage readings of 11.32 VDC and 10.94 VDC. Honda's OEM Zener Diode is 3.9B2, and I installed a new 1N4730A 3.9 V 1W Zener diode and my pink wire output is now a steady 7.34 VDC. This voltage is below the reported 9 VDC that many state the ICM computer needs to allow spark. I tried to start the bike and still no sign of firing "spark" at all. I even hooked up 9 VDC power supply to the pink wire at the ignition switch and still nothing from the engine.
May put the old factory diode back in and continue my trouble shooting.

I am at a loss on what to check next. Any help would be appreciated.

 

ECU is fine as shown by it running when using faked 9v. You may have excessive resistance somewhere. However, it running 2nd day without forcing 9v shows that was coincidental and there's 2nd issue that's not related to that.


1. measure battery-voltage with everything OFF, volts = ???

2. measure battery-voltage with key ON, kill = run, volts = ???

3. measure battery-voltage during cranking, volts = ???


With key ON, kill=RUN, measure these 4 points on ignition-switch (ignore backwards diode).



8. measure voltage on pink wire at ECU connector, volts = ???

9. measure voltage on blk wire blk ECU connector, volts = ???

10. unplug kickstand switch, measure resistance between switch-connector terminals in up position, ohms = ???

11. measure resistance between switch-connector terminals in down position, ohms = ???

12. measure resistance to chassis-ground of grn/wht wire at ECU connector, ohms = ???

13. measure resistance to chassis-ground of light-grn wire at ECU connector, ohms = ???

14. measure resistance to chassis-ground of grn/red wire at starter-solenoid, ohms = ???

 

Started the checks you provided and will continue later today and provide results. Thanks for your support.
1. Standing battery voltage with everything off = 11.80 VDC. I need to put a charger on the battery.
8. Voltage at pink wire at ECU = 7.45 VDC. I also measured the ignition switch side of the pink wire at the key switch and the voltage at the solder connection is 7.48 VDC.
9. Voltage at the black wire of the ECU connector = 11.28 VDC.

FYI - 2000 CBR 600F4 has 56,500 miles on bike. Bike is well taken care of, and looks showroom. Carburetors have never been taken out of motorcycle because bike has functioned perfect, until now. Only maintenance done to the motorcycle other than normal oil changes, tires and chains, is the fuel pump has been replaced four times. When my motorcycle would not start, I installed a new fuel pump in July but that was not the solution.

 

Battery comes 1st, it's beginning of everything. If it doesn't reach 13,5v on charger, replace it with one that does. Then repeat all tests above.

 

Results of my 2000 CBR 600 F4 testing Sept. 12, 2023:
1. Battery voltage with everything off = 13.0 volts (Recently charged. Battery new in June 2019)
2. Battery voltage with key on (dash lights on, head light on and marker lights on) = 12.02 volts
3. Battery voltage during cranking = 11.12 volts
4. Ignition switch 4 points - 1) At red/black wire solder point = 11.67 volts 2) At Zener Diode anode = 7.64 volts 3) At Zener Diode cathode = 11.65 volts 4) At solder of pink wire = 7.62 volts
8. Voltage on pink wire at ECU connector = 7.56 volts
9. Voltage on blk ECU connector = 11.38 volts
10. Resistance of kickstand switch connector terminal with kickstand up = 1.7 ohms and 0.6 ohms (reading bouncing around)
11. Resistance of kickstand switch connector terminal with kickstand down = OL - Open
12. Resistance of chassis-ground grn/wht wire at ECU connector = 50 m Ohms and I also got 28.6 m Ohms (reading bouncing around)
13. Resistance of chassis-ground of light green wire at ECU connector = 0.6 ohms
14. Resistance to chassis-ground of grn/red wire at starter-solenoid = 289 kOhms

During my trouble-shooting, I took the Honda Zener Diode out and replaced it with a 1N4730A new Zener diode that looked exactly the same. Should I put the Honda OEM diode back in as the new diode did not improve the no-start condition?

 

what is the resistance of your pulsar (pickup) coil?

 

#12 is your problem. it should be low ohms like #13 measurement

ECU thinks kickstand/neutral/clutch switch isn't working properly and kills spark. Same as putting kickstand down when engine's running in gear.

 

would that only be true if he was trying to start it in gear? if its in neutral then it doesnt matter if the side stand is up or down.

 

What corrective action is needed?
Test #12. Resistance of chassis-ground grn/wht wire at ECU connector = 50 m Ohms and I also got 28.6 m Ohms (reading bouncing around)
I have a Clymer manual for the 2000 Honda CBR 600 F4 that I should be able to follow out the wiring diagram for the green/white wire to the ECU.
Thank you for your support to resolve this problem.

 

if it's in neutral, then that wire would have low ohms to ground. That's how ECU knows it's in neutral or kickstand is up.

ECU is blind and can only "see" position of gears or kickstand based upon these switches working properly and transmitting their state to ECU.