YBR125 not starting - stuck

[Andrew G]

Hi there I've just joined the forum hoping for some advice on this problem.  I'm not a mechanic but always happy to read manuals, ask advice and try things and am handy enough with tools.

The ybr isn't my main bike, I had been using it from time to time and as a backup but couple years ago it stopped starting, now I'm trying to get it back to life .. as an economical alternative to big bike and cause I like it.  This is a YBR 2007ED fuel injected bike.

So after sitting for a couple of years, the problem had been fuel pump which wasn't working .. I replaced the impeller, and hey presto was riding up and down the road.  I left it alone with plans to service brakes, change oil etc, so I come back a week later and its failing to start again .. 

I am getting a flashing fault code, 46 - the Haynes manual says 'Abnormal power supply to FI system - engine will continue to run and can be restarted'.  But the engine doesn't run for me.

There is a good blue spark, also if I pull the injector out and fire the starter, I see the fuel spraying out which seems normal.  The only way it will run, if I take out the spark plug, put a teaspoon of fuel into the cylinder and replace spark plug, then the engine catches and runs for a second or two.  The battery seems fine by the way, I always kept it charged even while the bike was not getting used, and the starter motor turns well.

Things I have tried - on the advice of my local mechanic, replaced the throttle body / injector + all sensors, with a unit off ebay (no guarantees its works, but is a never-before-fitted part so lets assume it works) - no difference.  Also replaced the impeller again just to check.

Don't understand why it won't start .. local mechanic suggested maybe timing issue with the ignition .. like possibly a problem with crankshaft position sensor, but he didn't seem very sure.  I've read through the manual, it seems like a more involved job to replace CPS, and I need to buy some special tool + gasket ... hoping someone on yoc forum can give me some advice before I go and spend more ££ and time.....     

Thanks for reading, let me know if you folks have any ideas.

[slice]

Hi Andrew, welcome to the YOC. Must say you have done all the things I would have but your still stuck! How old is the fuel in the bike, have you put fresh fuel in it since you stored it? I only ask as if your firing when you physically put fuel in the spark plug hole it sounds like your NOT getting fuel to the cylinder, which is odd. If you turn it over on the button is the plug getting wet? Something between the injector and cylinder is blocking the fuel perhaps. Not worked on one of these so just guessing mate. A video or pictures really helps with this sort of thing. You might have a stuck inlet valve or even a broken valve spring whip the head off and have a butchers inside and see if there are any obvious problems. If not then come back and we can think of something else to spend your money on.

[finnerz89]

Looks like you've tried most of if not all the usual suspects. 

I have to admit as I was reading your post I was thinking crank sensor or pickup coil as they would dictate the timing of the fuel and/or spark.

[Cynic]

The battery, When you press the starter the starter motor will grab all of the electric, fuel injection gets starved and faults. Unlike a carb bike that will fire no matter the battery condition (in a lot of cases) as long as it turns over fast enough. Fuel injection is sensitive to it and it only needs to drop below maybe 12 v maybe a little less and it will not work. Mainly through self preservation, low volts increase current and electronics don't like it.

Give the battery a good desulphating charge or replace it. If im right it should bump start.