Diode drops fixed amount of voltage from input. So it should drop -3.9v from whatever battery voltage. So:

13.0v battery = 9.1v pink @ ECU
12.0v battery = 8.1v pink @ ECU
11.0v battery = 7.1v pink @ ECU

That’s why we want to know battery-voltage before starting. Anything less than 11-12v is too low anyway because it’ll drop too low when cranking to operate ECU. Measure following:

1. Battery-voltage with everything OFF, volts = ???

2. Battery-voltage with key On, stop-switch= RUN, volts = ???

3. Voltage on pink wire at ECU connector, volts = ???

4. Battery-voltage when cranking, volts = ???

 

Don’t waste time, ONLY thing we want to focus 100% effort on is:

1. +13.0v battery voltage with everything OFF, otherwise you won’t have enough power when cranking to run ECU. Might as well leave stop-switch off or remove engine from bike.


2. Battery voltage drop to 9v on pink wire at ECU connector


3. Proper BAS operation. Reduce green-wire resistance to ground from current 40 ohms to 0-ohms.


These are only things that’s preventing your bike from running. Any time you spent on anything else that’s not fixing these 3 items is waste. Because unless those things are fixed, bike will NEVER run!

 

Battery was at 13 volts when I checked it prior to these test. Also brand new battery . Been keeping it on trickle charge after testing everything. I'll work on these 3 steps you sent this evening and get back with you.

Thanks

 

Here’s some background. Everything is ground-triggered on this bike. That is, when something is activated: relays, injectors, coils, it’s connected to ground, NOT power.



So start-up sequence of events goes like this:

1. Key ON sends power to kill-switch

2. Kill-switch=RUN sends power to stop-relay

3. BAS activates stop-relay by grounding it

4. Stop-relay activates and sends power to ECU, injectors, coils, pump relay

5. ECU checks pink security wire for 9v, if OK, it triggers pump-relay by grounding it

6. Pump-relay activates and sends power to pump

7. When cranking to start, ECU triggers injectors by grounding them in pulses

8. ECU triggers sparks by grounding them in pulses

Trigger lines from ECU to fuel-pump relay, injectors and coils looks like this on oscilloscope, high (battery power) most of time, then drops to 0v (ground) when ECU activates them.



This is why it’s important that all green ground wires have 0 ohms to chassis-ground and battery -neg terminal. BAS connects engine-stop relay to ground on that green wire.

 

Should never have any voltage on red/wht because it’s activation ground wire for engine-stop relay.

It’s difficult to keep BAS upright and measure at same time. Let’s keep it plugged in and test in as-used configuration. Operational BAS connects grn wire to red/wht wire to have ground at red/wht at stop-relay to activate it.

1. You tested 40 ohms to chassis-ground on grn wire BAS socket connector


2. You tested good continuity end-to-end of red/wht wire from BAS socket connector to stop-relay socket red/wht.

This is by backprobing underside of relay socket with everything connected right? We want to keep eveything connected and test in as-used condition. Don’t want to change anything in course of testing.

If #1 and #2 is true, then you should also measure 40ohms to ground at red/wht wire under stop-relay socket. Might be something wrong measuring as it appears BAS is functional. What do you mean by this? What changes are you obvserving when you flip BAS up & down?

 

Let’s assume BAS circuit is operational for now.

Do battery & voltage measurements in post #41 above. It appears main problem is ECU doesn’t like status of pink security wire. Without proper 9v on that line, ECU will never get past priming pump and it won’t fire injectors or trigger sparks either.

 

Im currently following this thread and your step by step post about how to fix the issue of fuel pump not priming, ive spent all of yesterday going through your steps and im stuck on 8,9a,9b... and i think its because my relays arnt clicking when i turn the key, i have continuity through all the wires listed and all my fuses are good im just stuck and I dont know if its both relays because i keep swapping them to no avail so i would assume they are roasted, tested them and got 78 ohms from left side prongs(ill send a picture)

I also want to say im stuck on 4,5 as well now this might just be my own user error but i dont know what wires to test tbh
" 4. measure voltage of wht/blk input wire at start/stop switch, volts = +13v same as battery"
5. stop-switch = RUN, measure voltage of blkoutput wire, volts = +13v same as battery

is the black output wire the one that goes into the black plug?( ill also picture this)

Left top and bottom prongs is where i got 78 ohms on both relays.

Theres three solid black wires on this and i tried all three to no success.

 

So found out one of my test leads in multimeter was loose is why I was getting false readings yesterday. It finally came out. I checked these 3 steps with my old multimeter and results are..
Battery voltage 13.1
Pink wire 9.23
BAS has continuity between green and red/white unplugged. Also plugged in I can turn it upside down and it trips stop switch so is in good working order.
Still no pump prime.

 

Also resistance on green BAS to ground was 0

 

Also getting 12.8 volts on pin# 6 black ECU plug from fuel cut off relay when engine switch is in run position if that helps.