R850r Problems - Hall Sensor suspected

So a long story short, the bike belong to a friend of mine packed in a few months ago and he hadn't given me the complete picture He had mis fuelled his van with petrol, pumped it out and used the 'petrol' to fill his 850, needless to say it didn't run very well anyway he sorted that and all was well until recently when if would only start with a bump so he packed the bike off to one of his pals to 'sort out' who claimed it was an HT lead then cobbled it back together, it was then delivered to me last weekend. Andy, the owner of the bike, assures me that when it went to his other pal it was sparking on both pots.

So yesterday I got it on the bench and no spark on either pot, tank off and the HT leads & feed to the coil were disconnected so I tested the coil, all was well, tested the HT leads and the right hand side is u/s. Looking at the way the bike had been cobbled back together, one of the fuel line QD snap connectors was broken which I've replaced, I suspect the HT lead fell victim to ham fisted removal from the plug. After refitting/reconnecting the coil and popping the fuel tank back on I cranked the bike with the injectors off the result was (obviously) no spark on the right pot, a feeble yellow spark on the left pot and no juice from the injectors. My conclusion is that the Hall sensor has failed but before I spend the neck end of a couple of hundred quid of his money on a replacement and ideas if it could potentially be something else. I did think of the Motronic but as the spark is so poor have ruled that out. Oh and the battery is good, newish, and fully charged.

Thoughts appreciated.

Dave

Anyone?

It sounds like you're on top of the problem. Without either a GS911 or Hall sensor test box, there is no way of knowing for sure.

You can pop the plugs out, stick the bike in gear and with the ignition on, turn the engine over from the back wheel.

As the engine rotates, you should hear the pump prime. In an ideal world you should also see a spurt of fuel from both injectors (at same time) and then a spark from both plugs (again at the same time). Because you are not cranking the bike on the starter, full battery voltage will be there to power the ignition.

The trouble is, even testing the bike this way and getting fuel and spark, is still no guarantee that the Hall sensor is serviceable.

Good luck.
Ian

Thanks Ian, good idea to turn the bike over with the back wheel. I’ll give it a try.

Dave

If you do need a sensor plate they are available on eBay for around £95.
Seller is in Greece. I have bought from him several times.
Quick delivery and work fine.

Ian J Hartley said:

It sounds like you're on top of the problem. Without either a GS911 or Hall sensor test box, there is no way of knowing for sure.

You can pop the plugs out, stick the bike in gear and with the ignition on, turn the engine over from the back wheel.

As the engine rotates, you should hear the pump prime. In an ideal world you should also see a spurt of fuel from both injectors (at same time) and then a spark from both plugs (again at the same time). Because you are not cranking the bike on the starter, full battery voltage will be there to power the ignition.

The trouble is, even testing the bike this way and getting fuel and spark, is still no guarantee that the Hall sensor is serviceable.

Good luck.
Ian

Click to expand...

If you have no fuel pump priming/spark/injector fuel as turn the engine over chances are it'll be the hall sensor....... ..... But If you do have the fuel pump priming/spark/injector fuel as you turn the engine over ithat doesn't mean the hall sensor is working ok

Steptoe said:

If you have no fuel pump priming/spark/injector fuel as turn the engine over chances are it'll be the hall sensor....... ..... But If you do have the fuel pump priming/spark/injector fuel as you turn the engine over ithat doesn't mean the hall sensor is working ok

Click to expand...

I'll take it from that it's likely to be the hall sensor.

Thanks

casper said:

If you do need a sensor plate they are available on eBay for around £95.
Seller is in Greece. I have bought from him several times.
Quick delivery and work fine.

Click to expand...

Thanks, I'll have a look.

Most wrenchers seem of the opinion that actually it's not the HS unit itself that stops a bike from running, it's mostly the wiring to it that deteriorates and goes open-circuit or short-circuit.
Agreed Steptoe ? ?
AL

sykospain said:

Most wrenchers seem of the opinion that actually it's not the HS unit itself that stops a bike from running, it's mostly the wiring to it that deteriorates and goes open-circuit or short-circuit.
Agreed Steptoe ? ?
AL

Click to expand...

A quick test for hall sensors is the scratch test.
3 wire hall sensor has 12v , earth and the switch , which is taken to ground by the hall sensor as it passes the shutter.
Scratch the switch wire to earth will produce a spark and injection pulse.

R850 just stopped on me twice each time it restarted and each time the ignition lights were still on. The next time an hour later it wouldn't restart.
I have a good healthy fat spark and fuel pump is working. Iv checked the ignition switch and stop switch also wiring.
Is this a Hall snsr failure?

Bikesmikey said:

R850 just stopped on me twice each time it restarted and each time the ignition lights were still on. The next time an hour later it wouldn't restart.
I have a good healthy fat spark and fuel pump is working. Iv checked the ignition switch and stop switch also wiring.
Is this a Hall snsr failure?

Click to expand...

I’m assuming when you say fuel pump is working, It’s the initial momentary priming when you first turn on the ignition.

Have you checked to see if the injectors are spraying fuel?

Just pop an injector out of the throttle body, leaving fuel and electrical connectors connected. Put the end of the injector in a suitable container.

As you crank the engine all being well you should see the injector spraying fuel. If not, then likely a Hall Sensor failure.

Yes i have fuel injection spraying fuel I did suspect it too that's why i fitted a new pump and filter.
So after iv tested the stand switch, ill need to look further into the wiring.