Thursday, October 23, 2014

GSXR1000K6 - Fuel Pressure And Flow Problems.

Modern thou's are a bit quick...
Even when they have fuelling issues. Ride this thing on the road and any problems are barely perceptible, but once on the track there's a gaping hole where power should be chiming in - and it's gutting! 

So I did a bit of investigating.
Ok, we start with an in-tank fuel filter/pump assembly. It consists of a gauze at the bottom of the unit to prevent any dirt entering the pump. The pump then forces fuel through another larger filter assembly, and the built-in regulator allows any excess pressure to vent fuel back into the tank. 
This complete unit supplies fuel, at 43psi, to a rail containing eight injectors - four primary and four secondary. The primaries maintain the low end of the engine's needs, with the secondaries starting to open at around 4,500RPM and their duration (time spent open) is controlled depending on the angle of the TPS (Throttle Position Sensor). Sounds easy enough so far.

Then there's the exhaust valve. With the standard can still fitted, I'm still relying on the actuator to open and close the butterfly valve in the pipe. A quick look through the frame at the actuator/motor, when switching the ignition on, and it's obvious it isn't moving through its complete cycle. Another problem?


Symptoms and checking it.
As soon as you go to full throttle, it feels like it's being shut down. Bang, like a switch. Back off to 3/4 throttle and it seems to improve slightly, but the old Gixer's obviously got a major issue. 
I decided to whip out the fuel pump assembly a couple of weeks ago, to see if there was something amiss that could be fixed easily. I should've done the flow test at this point, but I was in too much of a rush to get the pump out. So, with tank removed, it was just a case of removing the five allen bolts and a bit of jiggling to have the whole thing out.




An easier job than you think - just be careful with the fuel level sender.



Dirty, rusty stuff congregating in the bottom. I gave it a clean out, including the gauze filter, and refitted it. Needless to say, it didn't solve the problem.



So today I was back on it. 
I still suspect a fuel issue so the bullet was bitten and a new fuel filter ordered from the States (still about 300 notes!). I also ordered one of the aftermarket pumps and gauze filters from Highflowfuel on eBay. Thought I'd run a flow test too and, stone me, I think we have a problem. According to the manual, you connect positive to the yellow/red wire and negative to the black/white wire, and collect the fuel in a jar. Above 168ml of fuel in ten seconds and all is well.

Nothing! The pump is running ok, but nothing at all was pumped out. I sucked on the pipe to see if I could move fuel and sure enough it started to come down the tube, but nothing when powered up. So either the flux capacitor is blocked, or something's just plain fluxed.

And so we wait... on parts.
But, on top of that, I thought I'd take a proper look at the exhaust valve in the can/silencer/muffler. Whenever you switch the ignition on, the ECU runs its little self-checks on various components, including the exhaust valve. I've looked at it before, watched it go through the motions, and largely ignored it. But today it was pretty obvious it wasn't getting full movement. Time to take it all off and check it over.
With RH footrest and master cylinder removed, it's pretty easy to get at. The actuator will come out with cables still attached to the silencer. No need to remove the fairing either, just remove a few clips and the lower, rearmost bolt.




With cables disconnected, the motor will actually turn right round when powered by the ignition - then logs a fault.


The exhaust valve itself is nice and free. 


But both cables have started to fray. I was going to make up new ones, but the nipple on the exhaust end is stainless steel, and peened or shrunk on. I take it the soldered types can't put up with the heat. Ah well, new cables ordered too.


Might leave it disconnected for a while and see how it goes and sounds. Already sounds louder just running it in the garage.


So now I just need the parts... can't wait!