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just got an SB8R! help me get it running! (no fuel or spark)
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SB8_#34



Joined: 16 Dec 2021
Posts: 24

PostPosted: Thu Dec 16, 2021 3:21 pm    Post subject: just got an SB8R! help me get it running! (no fuel or spark) Reply with quote

hi everyone!

i just picked up a SB8R that only has 2k miles on it and has been sitting for many years.

my first issue to resolve is getting the fuel pump to prime and run. When i turn the key on, i do not hear it.

-battery has good voltage
-fuses in box by gauges are all good, along with the 30A one closer to the battery and the ones on the relays
-pump runs if i put power straight to it (jumped the relay)
-starter will turn the engine over (not sure if that eliminates any issues related to kickstand switch, clutch switch, etc or if those even have anything to do with pump operation)

the relay for the pump has 4 wires:
-Red: +12V straight from the battery
-Red/ White: this should be power to the pump when the relay is switched on
-Red/blue: this goes to ECU, coils, injectors and other relay. it goes +12V when i turn the key on
-Black/Cyan: only to ECU

the other relay that sits next to this one. i can feel it click when i turn the key on so i believe it is working properly. i switched the 2 relays and they both click in this position, but i don't feel a click from the pump relay when i turn on the key (should I?)

maybe this is dumb, but i also want to note that i have the pump removed from the tank, so it is not submerged in gas. i don't think the sending unit is smart enough to say "there is Zero gas here, don't turn the pump on" as it looks like it only works to turn the low fuel light on, but thought i'd mention it.

i'm not incredibly intelligent when it comes to electrical stuff (mechanical engineer Shocked

any help is appreciated! thanks!


Last edited by SB8_#34 on Fri Dec 17, 2021 3:36 pm; edited 1 time in total
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Jaguar



Joined: 15 Sep 2017
Posts: 268
Location: Albany NY

PostPosted: Thu Dec 16, 2021 4:05 pm    Post subject: Reply with quote

Have you confirmed the handle bar switch is working correctly?
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Bimota (Tesi 1D 904SR, DB2, DB4, SB6,SB6R, SB8R, SB8K Santa Monica) Ducati (1000SS, Monster S4, 999R) Aprilia (RSV Mille R Haga) Honda (CL125s and 70s Chopper)
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SB8_#34



Joined: 16 Dec 2021
Posts: 24

PostPosted: Thu Dec 16, 2021 4:45 pm    Post subject: Reply with quote

Jaguar wrote:
Have you confirmed the handle bar switch is working correctly?


sorry, which switch?
starter works fine, ignition lights up gauges and all lights work (well other than a turn signal)

do you mean the kill switch? if so, what's the best way to do this? i did confirm it's in the run position because that's stumped me before

also i don't seem to have spark
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SB8_#34



Joined: 16 Dec 2021
Posts: 24

PostPosted: Thu Dec 16, 2021 7:09 pm    Post subject: Reply with quote

kill switch allows bike to turn over in run position, but not in off position
seems logical, but i believe i've had bikes where it would crank in off position and not start. so i don't think that is the issue.

what else can i check? i'm trying to rule out everything before i conclude it's the ECU

... really hope thats not the case!
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Jaguar



Joined: 15 Sep 2017
Posts: 268
Location: Albany NY

PostPosted: Thu Dec 16, 2021 8:11 pm    Post subject: Reply with quote

Yeah the kill switch.

I think it can be in the run position, allow the bike to crank, but also fail to let the fuel pump kick on.

If no fuel and no spark I would start looking at ECU faults.
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Bimota (Tesi 1D 904SR, DB2, DB4, SB6,SB6R, SB8R, SB8K Santa Monica) Ducati (1000SS, Monster S4, 999R) Aprilia (RSV Mille R Haga) Honda (CL125s and 70s Chopper)
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SB8_#34



Joined: 16 Dec 2021
Posts: 24

PostPosted: Thu Dec 16, 2021 8:45 pm    Post subject: Reply with quote

is there a way to read codes on the dash?
i know with Suzukis you could short across the diagnostic connector and it would put the codes on the dash.

imagine since it's not a Suzuki ECU that things work differently.

really appreciate the help so far, i didn't know if i would get any answers since it doesn't look like this forum sees much traffic
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Andrew034



Joined: 02 Apr 2017
Posts: 52
Location: Sydney

PostPosted: Thu Dec 16, 2021 11:09 pm    Post subject: Reply with quote

I'm not entirely familiar with the SB8, so I may be wrong here, however on first principles:

1. It is unusual, but not all systems will run the pump unless the engine is turning, so have you checked that the pump doesn't work when cranking the engine.

Since you stated you can get the pump to run by bridging the relay 2 more items:

2. Is the relay OK, I've had plenty of relays that "click" but don't actually transmit power - easy to check if you have a spare or another relay on the bike you can swap it with.

3. Given you can bridge the pump, with the bike start with a bridged pump, this can at least eliminate other possible failure points (e.g. major ECU issues).

I'll need more specific information to give better suggestions - eg a copy of the wiring loom diagram.

Finally, if you're playing with petrol and electricity together, remember electrical sparks are a really dangerous item - keep an extinguisher handy and make sure everything is dry and secure before aplying power.

Andrew...
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Andrew034



Joined: 02 Apr 2017
Posts: 52
Location: Sydney

PostPosted: Thu Dec 16, 2021 11:09 pm    Post subject: Reply with quote

I'm not entirely familiar with the SB8, so I may be wrong here, however on first principles:

1. It is unusual, but not all systems will run the pump unless the engine is turning, so have you checked that the pump doesn't work when cranking the engine.

Since you stated you can get the pump to run by bridging the relay 2 more items:

2. Is the relay OK, I've had plenty of relays that "click" but don't actually transmit power - easy to check if you have a spare or another relay on the bike you can swap it with.

3. Given you can bridge the pump, with the bike start with a bridged pump, this can at least eliminate other possible failure points (e.g. major ECU issues).

I'll need more specific information to give better suggestions - eg a copy of the wiring loom diagram.

Finally, if you're playing with petrol and electricity together, remember electrical sparks are a really dangerous item - keep an extinguisher handy and make sure everything is dry and secure before aplying power.

Andrew...
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SB8R Tuner



Joined: 29 Nov 2010
Posts: 83

PostPosted: Fri Dec 17, 2021 7:30 am    Post subject: Reply with quote

I would check to make sure the ecu is sending a ground signal to the fuel pump relay. That wire is black/cyan in color. Hook up a ohm meter between ground and the black/cyan wire.Turn on the ignition switch then turn on the engine run switch while watching the ohm meter. It should have continuity for approx 2.5-3.0 secs. The ecu runs a self diagnosis routine every time it receives power. If everything is OK it cycles the fuel pump relay for a couple or so secs.
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Bimota V-Due
Bimota SB8R
Suzuki 1988 GSXR-750
Suzuki 1989 GSXR-750R
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SB8_#34



Joined: 16 Dec 2021
Posts: 24

PostPosted: Fri Dec 17, 2021 1:48 pm    Post subject: Reply with quote

ok i got a spare battery and some banana clips.

i tested the relays and both are working properly- checked continuity between 30 and 87, applied power to 85 and 86 which closed circuit.

i do NOT have continuity from the cyan wire at the relay connector to ground. if i jump to ground, the relay closes properly and pump turns on.

i have also checked continuity from the relay connector up to the ECU connector for that cyan wire and it is good.

pump does not get power when cranking the engine either.

Here is the injection system schematic:



i was so excited to wake up and see more replies and people in here to help me!!! thank you so much!


Last edited by SB8_#34 on Fri Feb 04, 2022 2:20 pm; edited 1 time in total
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SB8_#34



Joined: 16 Dec 2021
Posts: 24

PostPosted: Fri Dec 17, 2021 2:40 pm    Post subject: Reply with quote

i don't see one mentioned on the schematics, but do these have a tip over sensor? seems like that could affect fuel and spark.
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SB8_#34



Joined: 16 Dec 2021
Posts: 24

PostPosted: Fri Dec 17, 2021 9:14 pm    Post subject: Reply with quote

so i was reading how some other manufacturers have a diode or resistor within the ignition switch to make hotwiring a bike more difficult. symptoms of sending the full voltage to the ECU would result in the same no fuel, no spark condition

Couldn't find much info on this one, so i took it apart and nothing special inside there.

cross ignition switch off the list of possibilites.
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Andrew034



Joined: 02 Apr 2017
Posts: 52
Location: Sydney

PostPosted: Sat Dec 18, 2021 12:34 am    Post subject: Reply with quote

Thanks for the wiring diagram, now I can see how the system works And it is as follows.

1. When the Ignition switch is turned on, the Pink wire in connector 14 is energised.
2. The Pink wire then provides power to right hand side Relay 7 which the activates and now provides power to the Fuel Injection System via the Red/Blue wires.
3. The Red/Blue wires also power Relay 7 on the right. However this will not activate the relay alone.
4. To activate the fuel pump relay, the ECU will earth pin #5 on the ECU connector. Which should be a Black/Light Blue wire.

So what does this mean:
When you turn on the ignition, you should feel at least one relay click and you can test to see if there is power on the Pink wire connector. Further at this point, all Red/Blue wires should be energised. If this is the case, you can pretty much rule out a problem with the ignition switch.

Assuming you have power in the Red/Blue wires, when you turn on the ignition (if there is a fuel priming cycle as another poster has stated), you should feel the fuel pump relay also activate.

The electrical test is a little tricky, because I find the best is to connect a volt meter (not a test light) to the Black/Light Blue wire while the fuel pump relay is connected (the test won't work if the relay is removed). Often I'll wrap a thin piece of wire around the correct pin on the relay and then insert the relay in its position. The other side of the volt meter is connected to the negative terminal of the battery.

With the power off, the meter will read 0v. When you turn on the ignition, look at the volt meter, if it reads 12v, the ECU is not attempting to operate the fuel pump relay, if it is reading 0v then either the ECU is attempting to operate the fuel pump relay or the relay is broken. If the reading is zero, a non definitive test is watch the meter as you turn on the ignition, there should be a momentary jump in the voltage reading if every thing is working OK. If the voltage is reading 12v, you can attempt to start the bike to to see if the ECU is trying to power the fuel pump.

As stated earlier, I would also bridge the fuel pump relay (to operate the pump) and attempt to start the engine.

Looking further at the diagram, there is also communication connector 18 that goes from the dashboard to ECU pin 23. What is missing, is I don't know how the engine cut off switch is wired. If it is connected to the instrument panel, it may be the dash is telling the bike not to start and like wise if there is a built-in security system, it may be telling the ECU (via the dash not to start the engine).

Additionally, does the bike have any type of aftermarket security system, in my experience about 100% of the time if there is a starting issue, the aftermarket alarm is the source of the problem.

Let me know what your findings are and we'll go from there.

Andrew...
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SB8R Tuner



Joined: 29 Nov 2010
Posts: 83

PostPosted: Sat Dec 18, 2021 6:00 am    Post subject: Reply with quote

Check the pins #17&34 on ecu connector for ground and pin #35 for +12v (ignition turned on).
If these pins check out correctly then you have a bad ecu.
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Bimota V-Due
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Suzuki 1988 GSXR-750
Suzuki 1989 GSXR-750R
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SB8_#34



Joined: 16 Dec 2021
Posts: 24

PostPosted: Sat Dec 18, 2021 3:33 pm    Post subject: Reply with quote

SB8R Tuner wrote:
Check the pins #17&34 on ecu connector for ground and pin #35 for +12v (ignition turned on).
If these pins check out correctly then you have a bad ecu.


confirmed ground for #17 and #34 and +12V for #35.

ok so if my ECU was functioning correctly, then the black/Cyan should be going to ground to activate the relay for the fuel pump? i just would like to be able to confirm what output i should be seeing.

i mean ECU does make sense if i don't have fuel or spark.

is this the only place that repairs these?
https://www.ecurepair.com.au/product/bimota-sb8r-32638-ecu/

does anyone have any experience with them? i mean i assume they've done it at least once to advertise an obscure model like this on their site!

also any leads for working ECUs?
i'm in the USA so shipping to Australia sounds scary!

Edit: found someone in the USA! anyone use them? looks like they're in the UK as well
https://www.carmousa.com/index.php?main_page=index&cPath=497_570_1407_1411
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