M900i.e. Cutting out at 8K

[otter1]

My 2000 monster 900 i.e. has done this a couple of times - if the rpms get too near 8k, the bike will start to cut out (It seems like I hit a rev limiter and the spark is cut to one cylinder). The rpms drop as expected, the tach needle fluctuates wildly between 3-6K and the engine dies.

I pull in the clutch and while coasting - hit the start button but it will not turn over. I coast to a stop (the first time this happened I looked behind me for a trail of blue smoke because I thought I had blown the engine - No smoke!)

I turn the key off and then on again (I hear the fuel pump actuating) and it starts. The bike runs perfectly otherwise - just does not like to be reved too near 8K

I did a search and read some posts about fuel pumps and dry carb bowls etc., but I think it is a ECU glitch?? If it was a coil or fuel pump issue it should restart without having to key it off then on again.

Thx for your thoughts!

[ducpainter]

When was the last time you changed your fuel filter?

[otter1]

It is new- I replaced it and the fuel lines this summer. Could it be the fuel pump cutting out?

[ducpainter]

It is new- I replaced it and the fuel lines this summer. Could it be the fuel pump cutting out?

Anything is possible.

I always start with the simple stuff, and a fuel filter is pretty basic.

The fact that it actually stops running is kind of 'interesting'.

I'm thinking electrical because of your description of the tach.

Does it do it every time you get close to 8 grand?

[brad black]

the tacho is driven by the ecu, so it can be issues with the following:

rotation sensor.
ecu power supply.
ecu.

[MonsterHPD]

It is new- I replaced it and the fuel lines this summer. Could it be the fuel pump cutting out?

Just a thought.... are all the fuel line clamps (in the tank) tightened properly? A mate of mine had a similiar problem (well, not the revcounter) with his 888 when the lines were cracked. Yours are new, so that would not be the problem, but maybe a clamp ...?     

[Desmo Demon]

I pull in the clutch and while coasting - hit the start button but it will not turn over.

The fuel filter, fuel lines, and ECU will not effect this. IIRC, the starter is a completely different circuit than the ECU (they both share the ignition switch, though - with the power being used to activate the starter button - you can actually get the starter to turn over without having the key on if you jump from the battery to the starter side of the solenoid, of which the solenoid is controlled by the starter button).

Does it refuse to restart every time without messing with the ignition?

Sounds like a short or bad ground that is agitated by the higher rpm vibrations. I wonder if you have a short in your ignition that resets when you turn it off and back on. It may also be a short or a bad ground and is just a fluke that it doesn't start while coasting (if you don't have to turn the key off and on each time). If it will restart sometimes, but not others, look at grounds first, such as cleaning the battery terminals and the grounding straps (negative terminal cable at the back of the engine.

[Howie]

Trouble shooting will be difficult since the problem is intermittent and duplicating vibration at 8K RPM is difficult.  A good starting point might be to change or bypass the main ignition relay.  A jumper wire between terminal 30 and 85 will bypass it.  Also carry a meter with you.  When the bike stalls, if safe, coast to the side of the road.  No power at terminal 85 for the main relay?  Ignition switch or wiring between.  No power at terminal 17 for the computer?  Wiring between fuse 8 and the computer.  This should get you started. 

Oh, before you go out and ride a stalling bike, with the bike running wiggle the harness and tap the main relay to see if the bike stalls.

[bdub]

My 2000 900ie was doing something similar and it was insulation rubbed off the wire inside the tank running to the fuel pump. It was very sporadic until it just quit. My pump would not run at that point.

[otter1]

Thanks for all the input! 

Unfortunately, 
I ended up selling the bike last week -- I told the new owner I was having the issue and advised him to check this thread. Maybe he can post the solution later...