Asking for some kind direction please.

1999 Gen 1 Hayabusa.

Car running perfectly last Autumn. Stripped the car down to bare chassis to re-powder coat. No other changes made. Have now finished the rebuild. Firstly I wasn't getting the fuel pump pulling in on ignition turn. No 12V supply at fuel pump relay on Red/Blue wire. Traced to the red and red/white wire on the starter relay not having permanent 12V feed out. This was due to the battery feed heavy cable attached to the wrong side of the starter relay. So inverted the battery/starter cables. 12V now at both red and red/white wires out of starter relay. Fuel pump priming. 12V at the injector rail for 4 secs until the fuel pump relay switches out when fuel pressurised. Also getting 12V at fuel rail injectors on cranking. So in summary no issues with 12V supplies to injectors.
When I open the throttle bodies all 4 injectors squirt 2x blobs of fuel then no more. Getting 43psi fuel pressure at the rail. Coils correctly working - getting spark.

All the loom mods are in place in the wiring loom - remember the car was running before I stripped it down. Have made no modifications to the wiring loom except for shorting the crank position sensor wires (soldered join). Have checked the contacts at the 2-way black connector and the wiring is correct in the plug housing.

So what sensors does the ECU have to see to activate the 4 injector switched earths?

[Edited on 16/5/19 by timbo7]

Are you still running the tilt switch?

tilt switch supply has been earthed... i assume this mod was completed as it ran before I started the refurb.

Hi!
I hade this problem to! 12v supply to injectors and fuelpump While cranking. But youst a tiny squirt and then Nothing. Totaly dead. Ignites on starting gas but doesnt start.
The ecu earth the injectors to open them.
I have very week Earth signal. Very unconsistent. First checked the Earth points. They were ok. Then checked rpm sensor=ok
Was sure it was a ecu fail. But i disconnected all injectors at same time. Put 12v direct on one injector and earth from a second battery and it was like a short circuit spark! No opening of injectors! So I tryed this again and at the same time tapping on the side of injector. And then it opend!! Repeted on all injectors. Plugged back hayabusas wiring And after that it starts perfect!
Later read of this problem. Injectors is very low tolerance part. They can styck
if not run for a long time or with rusted petroltank.
/Martin

Have you tried a set of noid lights to see if the injectors are receiving a 'pulse' signal from the ECU


Sorry not sure if the Busa is sequential or it batch fires the injectors? (either way there needs to be a signal)

hi Martin... has all the same sypmtoms as you state. Though I would not have expected all 4 injectors to act in the same way. Have a guy coming round who has tech to kick the injectors into firing so will be try that. Will keep you posted

I did not Think that to. I was very supprised. Haha Hours of fault finding...

Yeoooh😁👍🏻 got the old girl started. Injectors tested and were fine. My car has a quickshifter fitted with hard cut. I hadnt connected this when trying to get the non starting resolved. Without it connected I was getting spark but only one single pulse of fuel from the injectors.... silly boy me.

Thanks guys for the advise along the way