Problem with VBoost (electricity)

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adi.barda

Active Member
Joined
Oct 28, 2010
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Location
Petah Tikva Israel
Hi Guys,
My mechanic just finished replacing my old engine with new one. He never did that before on Vmax and I explained him about the VBoost mechanism.
He said it didn't have any special issues with it BUT, now after the new engine installed whenever I reach 6000rpm the bike is turned off same as switching it off from the main switch. I'm 99.99% percent sure that it is because of vboost. This situation is consistent.

Can anyone tell me what can it be, where to look? Any direction will help.

Thanks a lot!!

Adi Barda
 
When you turn the key to on, does the VBoost Servo cycle???? You can hear the 3 distinct "Whiring sounds" when it opens, closes and takes the slack out of the cable. You can also see this operation by looking between the front and rear cylinders at the VBoost linkage... As far as Killing the bike at 6,000 RPM,,,, ?????? Idon't have a clue yet...
 
when it dies, are you able to start it back up immediately? or do you have to turn the ignition off and back on?
 
I'm not sure. I need to check that again but I think I can start it again without turning the ignition switch off and back on.
 
open this: http://vmaxoutlaw.com/tech/VMX12-Service-Manual.pdf

and go to the vboost system troubleshooting section on page 7-64

if you end up having to check the condition of the leads and connectors, start following the gray wire that comes out of the tach. somewhere in the bundle it gets spliced into some yellow ones. these yellow ones lead to the fuel pump relay, the vboost control unit, and the ignition control unit. if those wires and the various connections are solid, start troubleshooting the fuel pump relay. if the fuel pump relay passes, start troubleshooting the ignition control unit. i haven't looked, but i would think that the troubleshooting guides for the fpr and the icu would be in the service manual that i provided. good luck.

{edit} just a wild guess, but i'm thinking that some device that is dependent upon rpms, is some how malfunctioning, or causing the black/red "engine run/stop" wire to short to ground.{/edit}

{edit2} also the yellow wire, connects up to one of the ignition coils--i am not sure as to which one. have a look at that and make sure everything is in order {/edit2}

{edit3} here's a link to the wiring diagrams, just in case you think you need one: http://pdfcast.org/pdf/yamaha-v-max-custom-wiring-diagrams {/edit3}
 
adi.barda said:
Hi Guys,
My mechanic just finished replacing my old engine with new one. He never did that before on Vmax and I explained him about the VBoost mechanism.
He said it didn't have any special issues with it BUT, now after the new engine installed whenever I reach 6000rpm the bike is turned off same as switching it off from the main switch. I'm 99.99% percent sure that it is because of vboost. This situation is consistent.

Can anyone tell me what can it be, where to look? Any direction will help.

Thanks a lot!!

Adi Barda
Click to expand...

I would direct you back to the mechanic who did the work & wired it wrong.
 
Thanks guys,
I don't trust the mechanic too much - especially not his electricity knowledge...
If I disconnect the VBoost connector - it makes sense that the problem will not reproduce right?
Of course in that case I will not have VBoost as well but just for check..
 
When it shuts off, is it instantenous like an electrical problem or does it kind of bog out a bit that it would be the fuel delivery? At least we can rule out one or the other..............
 
adi.barda said:
Thanks guys,
I don't trust the mechanic too much - especially not his electricity knowledge...
If I disconnect the VBoost connector - it makes sense that the problem will not reproduce right?
Of course in that case I will not have VBoost as well but just for check..
Click to expand...

Yes, I would try that first. I would unlug the square connector that feeds power to the vboost controller as seen in the attached photo
 

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yes, 95spfldmax. when it shuts off it is instantaneous like electric problem.
one more thing - regarding Ninjaneer's question - I checked it and after it shuts off I need to turn the switch off and back on in order to make it work again.
and one last thing I do have a problem with the ignition switch which I need to fix but having this problem happen on 6000rpm sharp makes me think it's a VBoost issue.

Thank you very much guys for all the responses!
 
adi.barda said:
...one more thing - regarding Ninjaneer's question - I checked it and after it shuts off I need to turn the switch off and back on in order to make it work again.
Click to expand...

this makes me think that a component/device is getting into a bad state and requires a reset in order to return to a more favorable state.

just thinking out loud. i don't know if what i'm thinking is possible, but when it shuts down, try to drain the carb's float bowls. my theory is: because the fuel pump relay, based on the wiring schematic, is dependent upon the tach, that perhaps it at around 6k it stops pumping fuel. then again, if this were the case, i would think that the stoppage would be more of a casual dying, not an abrupt dying like you describe. so if my second thought is worth anything, than perhaps the culprit is either the vboost control unit or the ignition control unit. so if you take out the vboost control unit and the problem doesn't go away then i would point my finger at the ignition control unit or the ignition coil with the yellow wire.
 
Thanks. this is what i'm going try ASAP. I'll disconnect VBoost and if the problem reproduce, I'll start looking for ignition switch. I'll update you on my progress and results.

Cheers!
 
By the way Ninjaneer, I'm also a software engineer and martial artist (18 years). One thing I would like to have is black belt in Vmax art of maintenance :)
 
adi.barda said:
yes, 95spfldmax. when it shuts off it is instantaneous like electric problem.
one more thing - regarding Ninjaneer's question - I checked it and after it shuts off I need to turn the switch off and back on in order to make it work again.
and one last thing I do have a problem with the ignition switch which I need to fix but having this problem happen on 6000rpm sharp makes me think it's a VBoost issue.

Thank you very much guys for all the responses!
Click to expand...


I think Ninjaneer has you covered here.

My thoughts to add are NOT to preclude the ignition switch immediately as it might still be a problem. It might be at 6000rpm that the vibrations are just getting ripe to cause a contact to disconnect. Possible...

In roughly the same line of thought, has it been road tested? Does it cut off at 6000rpm when riding?
 
adi.barda: Hang in here with this group and you'll have a VMax Black Belt in no time. This is the Library of Congress for VMax's...Great People too...
 
Yes bazwell. it cuts off in 6000rpm when riding as well (scary since we have lots of traffic here). it happens in any gear including neutral.
 
Could be an internal short on the geared motor or pinched wire that is shorting out. I would unplug the vboost to at least test it as you already noted.
 
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