Board logo

Help - Busa not running right!!
Tonto1 - 14/3/10 at 07:48 PM

Fired up my Busa for the first time after winter mods and sorting a problem with the starter.

Car starts and idles fine, with v.good oil pressure, but when it's warmed up I try to rev it and gets to around 6K and then starts miss firing, stuttering and won't rev any higher.

Winter mods consisted of upgrading fuel system with braided lines, Aeroquip fittings, Aeromotive regulator and Sytec pump. All of this appears to be working well with fuel pressure remaining constant. Have also checked all the filters etc and the seem fine (ie no blockages). Everything seems to be plumped up the right way.

I also tried re-fitting the old pump, which made no difference.

Also added new plugs, and then tried refitting the old ones, again no difference.

All coils seem to be fine have tried replacing all with a spare that I have.

Have put a temp gun on all the exhaust headers when running and these are pretty muh equal.

Battery has plenty of charge and voltage when running seems to be good.

Running out of ideas to check and it's doing me head in!!

dazzx10r - 14/3/10 at 08:23 PM

was the fuel system clean when you were working on it? have you checked all of the electrical conections to the TB's? Check the fuel rail make sure it's clean. I allmost wrecked a set of 08 GSXR TB's on my race bike when I had the fuel tank sandblasted, ended up with sand in the fuel pump, fuel rail and injectors!
Start from the fuel tank and work your way through the fuel system one step at a time, make sure you have'nt kinked the fuel hose (seen that one before!) what fuel pressure are you getting? you need about 42psi.

Jon Ison - 14/3/10 at 08:47 PM

All of the above, sounds very fuel orientated, are you running a swirl pot ?

richard thomas - 15/3/10 at 07:22 PM

Airlock in fuel rail?

Does your fuel rail have a return to a pressure regulator, I had something similar when I ran an original fuel rail where the regulator sits in the fuel pump....swapped to a westfield megabusa rail which cured the problem.

Tonto1 - 16/3/10 at 06:10 AM

Appreciate the feedback gents.

Swirl pot built into tank.
Have a inlet and out let on the fuel rail, so pretty sure there is no trapped air.

richard thomas - 19/3/10 at 09:22 PM

Do you still have the PAIRS kit fitted, or is it removed? Wondering if there is a leak within that?

Tonto1 - 20/3/10 at 07:11 AM

quote:
Originally posted by richard thomas
Do you still have the PAIRS kit fitted, or is it removed? Wondering if there is a leak within that?


PAIRS long since removed.



Still struggling with this one.

Pretty sure I can completely eliminate the fuel system as being the problem. As have tried with a second set of injectors and also tested the flow of fuel from the pump and through the fuel rail. (hayabusa manual states that fuel system should deliver a min' of 1.2Litres in 30 seconds, I got just over 1.5L)

Continued checking all the sensors and wiring, and haven't found any thing untoward yet.

However one thing I did notice when checking my Power Commander, was that when the engine wasn't running, but the ingition on, the PC software would accurately read the Throttle Position Sensor, however as soon as the engine was started the software would only read as if the throttle was fully closed, even when it wasn't.

I double checked all the voltages and wiring for the TPS with and without the PC fitted, including reading the TPS output voltages at the ECU plug and these all seemed good - vaying from 1.1 to 4.3 volts depending on throttle position.

Seemed strange why the PC software wouldn't pick up the TPS reading accurately when running. If the ECU was having similar problems and thinking the throttle was closed all the time, even when I actually have it wide open this could potentially explain the apparent lack of fuelling??

Can't think what could cause this to happen or what else to check!!

richard thomas - 20/3/10 at 01:28 PM

Are you running with the standard Busa clocks? There is a diagnosis facility on the clocks which throws up an 'FI' caption when an engine problem is sensed.....you can then interrogate it for fault codes.