Spinning on the starter - wont kick over

[bentombed]

2 hours ago, gstallons said:

When you go and try to start the bike and turn the switch to the key on position , does the fuel pump come on for about two seconds and turn off?  What lights sre on on the instrument cluster? Also are the headlights on ?

 Then when you crank the bike does the starter sound normal? 

everything that should happen does happen - except for the spark. lights, fuel pump, instruments all good.  It sounds like it should - just does not kick over.  I am now thinking ECU, as far as i can tell everything else is good 

[bentombed]

41 minutes ago, audiomick said:

Can you describe exactly how you came to this conclusion?

The connector for the sensor has three pins. As far as I can tell from the schematic, one of them must be a shield connection that goes off to earth at the ECU end. The other two connect to pins on the ECU.

If you can't find volts anywhere on the connector that the sensor plugs in to, bearing in mind that it is possibly only 5 Volts or something, not the full 12V, checking all the connectors involved is the first thing. I.e. the one the sensor plugs into directly, the one the ECU plugs in to, and any others in between.

If those are all definitely good, maybe the ECU has a problem.

I will double check - i couldnt get a reading off the cable the sensor plugs in to. I came to this conclusion as I had hoped that the sensor was the issue, it's not, there is something else going on.  Will have to check the ECU. 

[gstallons]

ooook

[Pressureangle]

4 hours ago, bentombed said:

everything that should happen does happen - except for the spark. lights, fuel pump, instruments all good.  It sounds like it should - just does not kick over.  I am now thinking ECU, as far as i can tell everything else is good 

The ECU tells the fuel pump to run, so it doesn't seem likely that's your trouble, though possible. To check the cam sensor depth, if you have no tools, hold the new and old ones up to each other so the end of each touches the flange of each. They will probably be identical so you can assume the shims that worked in the past will work with the new sensor. The shims are more likely to be dependent on individual case machining than difference in sensor length. Since you're already installed it, if the shims are in, ok. If you installed it without shims, pull to see if the reluctor has shaved the tip of the sensor. 
The schematic I have shows that the sensor is a simple analog coil, the third wire is in fact a grounded shield to keep AC voltage from messing with other electronics. The wires on the ECU side of the sensor connector should be tan and white, pins 7 and 12 on the ECU connector. With a second helper and a digital multimeter, you can test the sensor at both plugs for AC voltage output while you crank the motor. 
The coils are powered along with the fuel pump and injectors by the fuel pump relay. Fuel pump primes...Yes? pull an intake boot back, open the throttle and look with a flashlight into the open throttle body. When you first turn the key, or perhaps the run switch, the injectors should spray for a moment, to prime the engine. If you can confirm that you have fuel from the injectors and signal from the cam sensor, then we can look at the magic box. Until then, I'm with Dr. House; "It's never the ECU".

[Lucky Phil]

Whats the battery voltage when do you you hit the start button? How old is the battery?

 

[bentombed]

5 hours ago, Pressureangle said:

The ECU tells the fuel pump to run, so it doesn't seem likely that's your trouble, though possible. To check the cam sensor depth, if you have no tools, hold the new and old ones up to each other so the end of each touches the flange of each. They will probably be identical so you can assume the shims that worked in the past will work with the new sensor. The shims are more likely to be dependent on individual case machining than difference in sensor length. Since you're already installed it, if the shims are in, ok. If you installed it without shims, pull to see if the reluctor has shaved the tip of the sensor. 
The schematic I have shows that the sensor is a simple analog coil, the third wire is in fact a grounded shield to keep AC voltage from messing with other electronics. The wires on the ECU side of the sensor connector should be tan and white, pins 7 and 12 on the ECU connector. With a second helper and a digital multimeter, you can test the sensor at both plugs for AC voltage output while you crank the motor. 
The coils are powered along with the fuel pump and injectors by the fuel pump relay. Fuel pump primes...Yes? pull an intake boot back, open the throttle and look with a flashlight into the open throttle body. When you first turn the key, or perhaps the run switch, the injectors should spray for a moment, to prime the engine. If you can confirm that you have fuel from the injectors and signal from the cam sensor, then we can look at the magic box. Until then, I'm with Dr. House; "It's never the ECU".

I will check all these things - I am very happy its most likely not the ECU - i would have been very sad if had bought a replacement one and not fixed the problem.  

[bentombed]

4 hours ago, Lucky Phil said:

Whats the battery voltage when do you you hit the start button? How old is the battery?

 

its not old - I'll charge it up and test. 

[audiomick]

18 hours ago, Pressureangle said:

... "It's never the ECU".

But it might be the connections between it and the rest of the bike. 

[bentombed]

On 11/10/2025 at 11:56 AM, Pressureangle said:

The ECU tells the fuel pump to run, so it doesn't seem likely that's your trouble, though possible. To check the cam sensor depth, if you have no tools, hold the new and old ones up to each other so the end of each touches the flange of each. They will probably be identical so you can assume the shims that worked in the past will work with the new sensor. The shims are more likely to be dependent on individual case machining than difference in sensor length. Since you're already installed it, if the shims are in, ok. If you installed it without shims, pull to see if the reluctor has shaved the tip of the sensor. 
The schematic I have shows that the sensor is a simple analog coil, the third wire is in fact a grounded shield to keep AC voltage from messing with other electronics. The wires on the ECU side of the sensor connector should be tan and white, pins 7 and 12 on the ECU connector. With a second helper and a digital multimeter, you can test the sensor at both plugs for AC voltage output while you crank the motor. 
The coils are powered along with the fuel pump and injectors by the fuel pump relay. Fuel pump primes...Yes? pull an intake boot back, open the throttle and look with a flashlight into the open throttle body. When you first turn the key, or perhaps the run switch, the injectors should spray for a moment, to prime the engine. If you can confirm that you have fuel from the injectors and signal from the cam sensor, then we can look at the magic box. Until then, I'm with Dr. House; "It's never the ECU".

ok - took me a few weeks to get back to the bike - since my last check i can confirm i have power to the sensor, the sensor is brand new.  However i did not get a spray of fuel to prime the engine.  my voltage check to the injectors also got no reading. 

I suspected i may of had bad fuel as the symptoms matched so i have pulled out and cleaned the injectors and throttle bodies and flushed the tank of the suspect fuel. there was water in there.  the injectors are clear and sprayed happily on a bench test. 

i put it all back together, checked the injectors again and still no spray.
Now for the massive spanner in the works - My fuel pump has been rewired to a separate circuit- I realise i should have mentioned this earlier,  I dont know why the PO did this mod, i dont know how to undo it, but it will mean the power for the injectors/coils may come from a different source, the signal wires from the ECU have also been changed at some stage as they have different colours and joins on them. 

 on the wiring diagrams the power for the injectors and the coil is the same circuit, i am not sure for my bike. 

i have power to the fuel pump, the number 5 relay clicks, the fuses are good, but i'm going to need to follow a few more wires to figure this out.  I'll post photos up shortly. 

 

[bentombed]

the fuel pump is on its own relay and fuse - 

the circuit goes from the battery to the relay then to the pump - when you turn the system on it does not stop priming like on a stock bike- if you pull relay 5 the fuel pump still goes,  it only stops if you pull the fuse on the additional circuit.  I cannot tell if this circuit needs to be active for the coils and injectors to work.   it also appears as though the loom has been changed at some stage as the wire colours for the injectors from the ECU are different. 

Edited November 26 by bentombed

[bentombed]

Just now, bentombed said:

the fuel pump is on its own relay and fuse - 

the circuit goes from the battery to the relay then to the pump - when you turn the system on it does not stop priming like on a stock bike- if you pull relay 5 the fuel pump still goes,  it only stop if you pull the fuse on the additional circuit.  I cannot tell if this circuit needs to be active for the coils and injectors to work.   it also appears as though the loom has been changed at some stage as the wire colours for the injectors from the ECU are different. these wires have been changed at some stage, the originals are still in the loom but have been replaced.   

 

[bentombed]

Just now, bentombed said:

 

wires everywhere - its a cliff jefferies ecu if that makes any difference. 

 

[bentombed]

On 11/10/2025 at 5:21 PM, bentombed said:

its not old - I'll charge it up and test. 

Hey again - fully charged the battery was at just under 13v - with the bike on dropped to 12.7 - hit the starter it dropped to 10.3 
the battery is less than a year old, but it could be the issue

Edited November 26 by bentombed

[Lucky Phil]

7 minutes ago, bentombed said:

Hey again - fully charged the battery was at just under 13v - with the bike on dropped to 12.7 - hit the starter it dropped to 10.3 
the battery is less than a year old, but it could be the issue

Battery has dropped a cell. 

[bentombed]

1 hour ago, Lucky Phil said:

Battery has dropped a cell. 

that would explain it - i'll get a new one.  Whats the tell?