ECU only grounds injector wires to fire them. Injectors must have power 1st. Here's sequence of eventls:

1. 20a FI fuse goes into engine-stop relay fulltime.
2. 30a main fuse sends power to ignition-switch
3. key ON, ignition-switch sends power to start/stop switch
4. start/stop switch RUN, sends power to engine-stop relay to activate it
5. engine-stop relay ON powers: main/secondary injectors, TPS, ignition-coils, O2-sensor, ECU, exhaust valve
6. engine-stop relay ON also powers fuel-pump relay's input-power AND activation coil input
7. ECU grounds fuel-pump relay's activation coil's ground and turns ON fuel-pump relay
8. fuel-pump relay ON powers fuel-pump

Only thing fuel-pump relay affects is fuel-pump power and that's it. So... if you get fuel-pump prime, then ALL above steps are working.

Clue here is disconnecting injector disable starter. Which is extremely odd because starter-circuit doesn't connect to injectors in any way. So something between those 2 circuits is crossed-up and connected somehow..

1. test disconnecting some other injector, does that still disable starter?
2. after fuel-pump primes, measure for power at ECU connector, injector connectors, coil connectors and input to start-button
3. disconnect injector and re-measure input-power to start-button

Diagram is for 08+. Some colours may be different, but power-circuits and relays are same.

 

Let's trace the starter-solenoid circuit and verify it matches factory OEM configuration. Along the way, we'll probably find where it's connected to injector wiring. Will need to cut out harness wrap to trace wire. Be neat and don't disturb wire too much, we'll wrap it up with electrical tape at end after everything's fixed. Make sure insulation is intact and no bare wires anywhere.

1. pull headlight relay and connect charger, this may take while. Don't want to kill battery.

2. disconnect injector so start-circuit doesn't work

3. begin at starter-solenoid 4-pin red connector. Measure voltage at red output wire. Volts = ???

4. trace red wire away from solenoid, it'll branch off towards RR. Verify this branch is whole and not touching anything else.

5. continue tracing red wire, another branch goes towards fusebox. Back-probe fuses E-fan & F-odo have power on both input & output legs. Volts = ???

6. continue tracing main red wire all way to igntion-switch. There's another red wire in bundle, do not get them mixed up, stay on target! Make sure wire is intact entire way and not touching anything else. Measure voltage at red wire on connector to ignition-switch.

7. measure voltage red/blk wire at connector, volts = ? Key ON, measure voltage again, volts = ???

8. red/blk output wire becomes RED after connector (different wire than input). Trace this red wire back to fusebox. Make sure wire's continuous and doesn't connect to anything else

9. measure voltage on input & output of A fuse (headlight & starter), volts = ???

10. trace blk/red coming out of fusebox, is it continuous, unbroken with nothing connecting to it all way to other end?

11. one branch of blk/red ends up at headlight relay. Measure voltage of blk/red at relay socket. volts = ???

12. trace blk-red to start-button connector. Measure voltage of blk/red at connector, volts = ???

13. measure voltage of yel/red start-button output at connector. volts = ??? Press start-button, volts = ??

14. trace yel/red wire back to starter-solenoid, making sure it's intact and doesn't contact anything else. Measure voltage at solenoid connector when pushing start-button. Volts = ???


IF starter doesn't spin when pushing start-button, somewhere along way, you may encounter something different than described above. Some other wire tapped into starter-circuit wiring. Also where power disappears is also sign something's interefering.

 

In about 3 hours I am attacking this. I will let you know. Thank you. That is awesome feedback.

 

So I had some minor personal issues that have prevented me getting time to work on the bike. (Funny when you get asked to move out you don't have access to your bike. haha).

anyway, sorted that out now so back to the bike this weekend. I will go through everything you have listed above step by step and write results. Quick question before I do all that, can you test fuel pressure by measuring amount of fuel that comes out fuel hose at fuel rail when pump primes and how long it primes for. Reason for question is that everything you have all said is that injectors get power early on and everything else seems to be working so I wondered if the injectors won't open if there isn't enough pressure from fuel supply. And if I spray start assist spray it runs so I keep wondering if I have an issue with the amount of fuel that is coming from the pump. I have a newish pump but the pressure regulator isn't new and seeing as it sits in the same bracket as the fuel pump maybe it didn't like it when the fuel pump was changed recently. Whilst it has run since the pump was changed maybe the regulator was just holding on and then died a month later. Also thinking about it, I don't have any error codes so back to FUEL.

Anyway, that is just a secondary thought.

 

yeah, fuel-pump can be separate issue also. There's zero-pressure flow test (yours may not have quick-release fitting, but same idea).



Then there's actual pressure test. Failing pumps might have sufficient volume, but may not develop sufficient 50psi pressure. FPR or filter might contribute to pressure problems.

 

Awesome. That is unreal. As I said, the fuel pump has been changed about a month ago and worked fine but the pump kit I bought didn't come with a regulator which is the 50psi part. If that is the case I can now test to see if the regulator is not working and not providing enough pressure to send fuel through the injectors and then confusing me to think the injectors are not working when in fact it may not be them. I can't wait to test and see if that is the problem.