YZF R15 Starting issues

[rc_36_rider]

Hi all,

I have an R15 bucket and over the last couple of days I have Fitted a new cam and swapped out the EFI for an OKO carb. I turned the fuel system into gravity feed by removing the fuel line from the pump to the tank outlet and removing the power wire for the pump inside the tank. I also un plugged the injector and cut off the loom bundle that would have gone to the tail light and indicators etc.
Now when I try to start the bike the dash lights up as per usual and the tac cycles but I have no neutral light and the bike wont crank over on the starter, I tried to push start it but it doesn't want to push start either.

Anyone have any good ideas?

I also tried plugging the injector back in and bridging the connector that would have powered the fuel pump to try fool the ECU and that didn't help. Still not sure why I have lost the neutral light, wonder if I have cut off something important in the loom bundle...

[Yow Ling]

probably a blown fuse from when you shorted out the fuel pump connector

[rc_36_rider]

probably a blown fuse from when you shorted out the fuel pump connector

Nope, checked that, fuses are all good.

[Grumph]

I seriously don't want to get into this, but....

The ECU will need a TPS to work. removed I assume ?
Yamaha have a track record of requiring various - what might be called non - essential - fuctions to be connected before you get a spark.
Do you actually have a spark ?

[rc_36_rider]

I seriously don't want to get into this, but....

The ECU will need a TPS to work. removed I assume ?
Yamaha have a track record of requiring various - what might be called non - essential - fuctions to be connected before you get a spark.
Do you actually have a spark ?

Cheers for that I didn't think of trying the tps plugged back in, sadly no spark still. When I first asked my question I hadn't checked for spark yet because bump start was all I had tried (no kick)
I have since plugged in everything I can except the fuel pump, had to jump the solenoid to get it to crank over and yep no spark, still no neutral light either.

I'm starting to think I may need a race ecu to get it sparking again.

[speedpro]

Any chance of putting all the ECU, TPS, sensors, pump and stuff back together? If so, and it goes you can then remove bits one at a time until it stops and then figure out a way to make it go with that bit missing. Then carry on removing bits.

Or just replace the whole lot with an Ecotrons engine management system and run injected.

[rc_36_rider]

Any chance of putting all the ECU, TPS, sensors, pump and stuff back together? If so, and it goes you can then remove bits one at a time until it stops and then figure out a way to make it go with that bit missing. Then carry on removing bits.

Or just replace the whole lot with an Ecotrons engine management system and run injected.

I got to the stage of having all the electronics I removed plugged back in last night bar the fuel pump, and still no crank, no spark and no neutral light.

What really concerns me now it that I have cut something off the loom that was needed, but the only things I cut off were plugs that had nothing plugged into them when the bike was running.

The no neutral light really has me confused I'm not sure what I could have done to upset that and I'm also wondering if the bike has a kill to stop it starting when in gear "when it thinks its in gear"

The reason I went to the effort of fitting the carb was to get away from the need of a dyno and or data logger to tune the efi, carbs are far easier to tune by the plug reading and seat of the pants o meter.

[Grumph]

You need to go round with a multi-meter and check that you've got power where it should be when it's turned on.
And - sidestand switch ? oldie but a goodie...

I remember Hepburn shaking his head over the first GSXR1000 racebike, turned out that for some reason the indicator relays had to be left in circuit...

[F5 Dave]

Ha! I was just about to say side stand switch. But no neutral light seems to indicate its some starting override. Clutch switch needs to be pulled etc.

[speedpro]

No neutral light - it thinks it's in gear. I'd be looking for a wire that should be connected to the neutral switch on the gearbox

[FJRider]

Ha! I was just about to say side stand switch. But no neutral light seems to indicate its some starting override. Clutch switch needs to be pulled etc.

No neutral light might indicate a bulb blown ..

The kill switch or no power to the coil .. ??

[rc_36_rider]

So it just keeps getting interesting, I re connected the fuel pump last night so everything I disconnected is re connected now. When I turn on the ignition the dash lights up, the neutral light and other idiot lights light up , the tach cycles and I can hear the fuel pump run for a moment, then the idiot lights go out after their initial test ? and still no crank.

I have tried putting the neutral light wire to, ground, to power and just having it unplugged and still no neutral light.

The side stand and everything relating to it was long gone when I got the bike.

Also the clutch switch was never hooked up when I got the bike so I'm not 100% sure where it went into the loom but believe I located that spot and tried bridging that, still nothing.

I got out the multi-meter to start testing for power and the battery went flat after 30 seconds!! I will get a new battery today and s

I checked all the plugs I cut off and they are all open circuits so cutting them off should make no difference.

I'm starting to wonder if something has crapped out in the couple of days I had the throttle body and electrics off or disconnected while I was sorting the cam bearing and now I have gone to run it it's not something I have done but a coincidental failure that is stopping it...

[Grumph]

So you've proved that the fuel pump has to be connected to make things work. A work-around for a similar setup on FZR's was suggested to me - put the pump feed to earth with a 20 ohm resistor in the circuit. I had other problems with that one so haven't been able to prove if it works yet.

At least some of your cranking problems could well have been the battery.

[rc_36_rider]

Ok I have had success, got neutral light back, spark back and cranking on the button back.

I decided to remove all the insulation from the part of the wiring harness that I cut off that went to the tail lights etc. I discovered three different groups of wires all going into it about 100mm joining together then going back into the main harness, so I had open circuited all of them. One group was 4 blue wires all joined into one for the neutral light, and there were three brown/yellow wires all connected together so I reconnected them and got spark. There were about 10 earth wires joining together, I joined them all and got it cranking over and then removed one at a time until I only had two connected and still cranking over. I'm guessing they are the earth for the solenoid to start button circuit.
After that I started unplugging all the stuff for the efi one at a time to see what I had to have and it turns out the only must have is the tps, didn't need the injector or the fuel pump or the air temp sensor.

So if anyone is going to cut off the loom going to the taillights either remove the insulation and make sure you don't cut the above circuits or easier yet, leave it on there!

[rc_36_rider]

The wire war is not over yet, I removed the TPS from the TB and cable tied that to the bike, she ran for about 5 minutes then stalled, I thought it may have just flooded. I removed the plug it was looking rich but had no spark, tried a spare plug, still nothing
I talked to a mechanic at work who suggested the TPS may need to be connected to the TB, so I tried that last night, initially no spark still but then I twisted the throttle on the TB and instantly got spark. So sadly with the stock ECU you have to have the TPS connected to the TB to get continual spark. I guess if you knew what kinda resistance the TPS was reading you could get rid of it all with the correct resistor or rheostat wired in place of the TPS.