1993 R1100RS: will not start

[markinaz]

'93 R11rs: Switches on and the fuel pump runs then shuts off. Pump does not run during cranking. There is power to the injectors during switch-on, but no further signal during cranking. No spark either. Coil resistance tests are OK and the coil will generate a spark when connected to a battery. 12v at green power feed to coil. The battery is 100%. 3-Pin adapter testing generates only the Hall sensor warning. Nothing else. Direct test of the hall sensors indicates that both sensors are good. No visible damage to wiring although I did not remove the sensor plate from the engine. There is no visible damage to the wiring harnesses, junctions, or connectors.

Any ideas?

[Jughead]

All symptoms you describe would indicate a faulty hall sensor, despite the fact that it appears ok.  The wiring on the back of the hall sensor plate normally degrades, preventing the required pulse to get the motor running.

What you will typically find looks something like this:

[markinaz]

Yes, I've seen that before. In that case though, the Hall sensor tested negative. On the RS I removed the front cover and the crank pulley to get a good look at the plate and the wiring cover above the plate appears to be fine, I was just trying to avoid pulling the sensor and having to reset the timing (if possible). However it would seem that the next step is inevitable.

My supposition was that the ECU is not getting the signal that the crankshaft is turning and therefore not activating the coil, fuel pump, nor injectors.

[schuppi]

Hello
Anyway, it's necessary to measure the hall-sensor.
Input > 12V
Output > changing from 5 to 0V.

4Pin Connector 3+4 > brown+red 12V only with ignition on
                         3+2 > br+black 5V changing while turning the crankshaft only with ignition on
                         3+5 > br+orange 5V changing while turning the crankshaft only with ignition on

If there is no changing to 0V the hall sensor is faulty. Oftentimes there are problems with hotness.

Hope this helps

[Jughead]

... I removed the front cover and the crank pulley to get a good look at the plate and the wiring cover above the plate appears to be fine ...

You will not be able to see the deterioration without removing the unit, turning it over , and cutting it open.

[markinaz]

All of the wiring looked fine but some of the engine side of the outer sleeve had melted. Although the sensor tested OK, we replaced it anyway. Plugged it in and when the engine cranked there was an nice fat spark and the fuel pump lead received power. All's well now.

Thanks

[Jughead]

[emoji106]

[schuppi]

Hello