2005 S4R (Desmoquattro)

[DucHead]

Hi All - been a long time since I posted!

My '05 S4R was stalling like it was out of gas after a few minutes riding.  Gas was fine (no water in tank), so I decided to check all the hoses, fuel filter, pump, etc., in the tank.

Everything looked fine until I tried to remove the fuel level sensor.  I had to break it to remove it, and the reason it was stuck was that it was cracked vertically and swollen so as not to slide out the bottom of the tank.

I've ordered a new sensor, but would a broken level sensor cause the bike to stall after a few minutes running?   

[ducpainter]

 No proof, but I don't think so, Dave.

[DucHead]

Thanks, I didn't think so and a search turned up nothing but I thought I'd ask.

[Orange16]

If it has a broken wire inside the sensor, but that's rare on S4R.

When you turn the key on, the fuel pump should run for a short time.  That indicates the pump, circuit, ECU, etc are ok in general terms.

When you press the start button and the engine turns, the CPS (Crank Position Sensor), oddly enough sensing the timing gear in these engines, is triggered by the timing gear moving past it.  The signal it sends to the ECU then prompts the ECU to earth the coils/injectors/fuel pump relay again and the engine runs.

If the CPS has failed, and typical failure is to stop producing a signal after a period of time, the ECU doesn't get the signal and so simply sits, waiting.  You can check the resistance between two of the three wires.  Should be 600 to 800 ohms.  One of the wires is an earth shield, and has no continuity to the other two.

Check to see if the fuel pump relay is being activated while cranking.  If so, the CPS is ok.  It may also be a faulty relay, etc, so keep an open mind.