WON'T REV OVER 4500

K

knockoutms

Registered
i went to start my busa up yesterday, i let it warm up for about 10 minutes.  I got on it to take down the road and i reved it up a little bit and it stalled at around 4500 rpm and auto shifted on me.  so i tried it again and it did the same thing.  i unplugged the auto shifter and all the after market electronics except for the power commander and tried it again.  This time it revs to around 4500 then drops to 2000 or so and continues that until i get out of the throttle or it dies.  But as soon as it spudders at 4500 the fi light starts flashing at a consistent pace.  it idles just fine and as long as i rev it to 3500 or so its just fine.  as soon as it stalls at 4500 then the fi light comes on.  its an 05 busa.  i just wondering what sensor it could possibly be or something.  i have been connecting and disconnecting my battery alot this week.  could that have done something.  
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oh yeah and the speedometer goes crazy when it stalls to
thanks
 
check your throttle cable at the switch housing, bro-might be loose connection. I ripped mine out completely once just givin the bike ah...."judicious throttle input"
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fugger turned off and when I got it back started, as soon as I tried givn throttle, she shut down...would idle fine tho.
might be worth a look
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Did you check to see what code?
What year bike? Mods?

I just had this problem, but mine would wouldn't rev past 8K. Didn't throw a code, but ended up being black fuel pump housing in the tank.
 
05 bike with mps auto shifter, progressive nitrous system, power commander but everything is unplugged now and still doing it. don't know how to get the code off of it!

thanks
 
To check the code; there is a connector under the front seat on left side of bike that has a black rubber cap on it. Has nothing going to it but two wires on one side. Jump the two wires with a piece of wire or paper clip and look on the dash for the code. Should be a C-# if something is wrong. Post up the code and we can tell some more.
FI light has to be flashing. Once you turn off the bike it resets the ECM and will show no code until it happens again. So go for a ride until the light comes back on, leave the bike running and jump the connector and look for code.
 
If I read this right, you disconnected the PC.

cam sensor, cam gear loose (if aftermarket), injector....., Fuel pump (have you been running exotic fuel MR9 U4) Like PipeFitter said, you should have a code. Need to pull it.
 
i will work on getting the code this afternoon and then i will post what it is either tonight or early in the morning thanks alot guys!!!

93octane only and no aftermarket cams or anything!
 
did the code trick (thanks so much)
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code came up as c32-c35 which was my fuel injectors. i checked all the wires and they are solidly connected so tonight i'll test the resistance of each injector and find out which one it is. again thank you guys so much!!!

i'll post again on this when ever she's back running good again!!!


P.S. i love the pmra
 
well, ended up being bad news i guess! checked resistance, continuity, and voltage of each injector and everything looks good. according to the service manual. So i guess that means my ecm is done for!! Any other suggestions or advice would be greatly appreciated. I'll be back on the board early in the morning!

thanks
 
It would be a good idea to verify that fuel delivery before jumping into a new ecu...

Fuel pressure and quantity are pretty critical to the FI system..

When it acts up does it zip right up to rpm and quit or does it act like it takes a bit to get to the rpm?

Electrical injector problems are normally off/on type failures where fuel pressure tends to feel a bit lazy before the failure (pressure drops until the motor does not want to run)..

we use timing lights to watch the injector patterns on motors and you can usually see a weak fuel pump by a limp spray pattern.. never tried this on a busa however..
 
just as responsive as normal up to the 4500 rpms or so then drops to 2500 or just dies. according to the codes it had nothing to do with fuel delivery though. but i will check that for sure.

thanks
 
Mine did throw 2 codes during one ride when I was having problems.
If I remember right it was c32 and c35. Two inj.
Replaced the fuel pump housing which I guess has a filter in it also, and have never had any problems since.
Bike wouldn't die or nothing. It just hit that one spot and wouldn't do nothing else no matter how much throttle.
 
Are you getting C32 C33 C34 and C35 or Just c32 and C35... C32 is injector #1 C33 is #2 and so on.

Are you running a Fast FI (richen for N20) or using a MPS Kill (connectied to the injectors)

Might want to look at the harness where the ECO plugs in to make sure pins were not pushed back.
I've heard of PC IIIusb going bad, you say yours is disconnected.
Injectors maxed out.. by PC settings.

PM'd you about the ECU.
 
Install a new fuel pump setup,regulator going bad...ecm is either on or off fuel wise it doesn't halfway burn out...
 
i received all 4 c32, c33, 34, c35. i have a power commander that tuned. my nitrous kit is a wet kit with it's own fuel pump. my mps auto shift kill box is attached the coils not injectors. so far we have found no bad connections of pushed back pins or anything else but am going to continue looking at that kind of stuff. The fuel pump and regulator will be the next to check i guess. but i can still not figure out why my speedometer and tach are jumping around when it hits that stall point. And also why when my autoshifter is hooked up it will shift at that point!

thanks

i pm's you professor
 
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