R850R – it wont start???

[Grant Freeman]

#3332

Hi Guys,Last night leaving work, my bike started and ran for a few seconds (choke open to warm up) and then it cut out and will not start at all. There is fuel getting to the cylinders but no spark?I tried the obvious things like plugs and wires, and did a visual of the fuses which seemed all OK, side stand cut out etc. I had to leave it at work so that a mate could give me a lift home, but am now wondering where to start looking.Any advice much appreciated.Cheers.

[Robin]

#13780

Reminds me when my 1985 R80 wouldn't start. Tried all the rider/owner does and finally took it to the 'shop. Turned out to be the ECU. (That's the Electronic Control Unit.)

[Ron McFadzien]

#13781

Hi Guys,Last night leaving work, my bike started and ran for a few seconds (choke open to warm up) and then it cut out and will not start at all. There is fuel getting to the cylinders but no spark?I tried the obvious things like plugs and wires, and did a visual of the fuses which seemed all OK, side stand cut out etc. I had to leave it at work so that a mate could give me a lift home, but am now wondering where to start looking.Any advice much appreciated.Cheers.

Did they replace the wires from the sensors up to the plug when you had this problemhttp://forum.bmwor.org.nz/index.php/topic,1473.0.htmlif not you have the same problem. The injectors wont be firing same as there will be no spark. Due to the heat and the poor wire used the insulation breaks down and any moisture and everything shorts outregards boGSer

[Murray]

#13782

MikeIf it just stopped running without any prior indication of problems, most people will immediately point to a Hall Sensor failure. Might be true, might not. There are a couple of things you might try first though. Turn the ignition on and turn the handlebars right to left to the stops and back again. Does the fuel pump run continuously? If not check the wires around the control switch block. Check those wires anyway. Check all the wires around the head, a short in the wire from the tachometer where the wire crosses a frame member will cause this problem.On oil heads there are two Haul effects sensors mounded on a steel place the fits on the front of the engine behind the drive pulley for the alternator, check the pick-up wires. If you run the bike hard more often than not these do have a tendancy to melt, or at least get very brittle and crack letting moisture in. Also check the injector plugs on top of the control bodies, possible that there's a wire dislodged or broken there somewhere. At the extreme end, check the battery tray. Earlier models of the 850R had an acid battery, some without a breather pipe before that was sorted and if acid has spilled it would eat through the tray and compromise the wiring below. Like I said, an extreme possibility. Your other option is to find someone with a diagnostic tool or get it to a dealer, it may register and tell you where the fault lies.CheersGarry

[Grant Freeman]

#13783

Hi Guys,Thanks for the comments and suggestions. I checked it out at lunch time, had a multi meter across the Motronic fuse - it did not give an immediate full scale deflection, so I changed it for a new one that did, pulled the relays and cleaned the contacts, pulled the fuel injector electrical connections and air box, cleaned those contacts, boxed it up, pulled the choke out and it fired first pop! 😆It did have a fuel smell yesterday at my attempts to start it and when I pulled the plugs they were wet, so maybe it was just having a moment, but come the weekend I will have the tank off and clean all electrical contacts etc.Thanks for your help - most appreciated.Cheers,Mike

[Ron McFadzien]

#13784

Mike good to hear that your bike is going again. Looks like Garry missed the link in my post about the previous issues you had with the hall sensors.Back to that I will say from my own experience that the hall sensors can be replaced and your bike may go for 6 months but if the wirring from the hall sensors up to the plug has not been replaced then it is going to let you down again sooner or later mine went for about 6000kms without missing a beat and then stopped. This wire needs to be capable of withstanding temperatures up to 150 deg Cgood luck boGSer

[peter.trub]

#13785

Normally lets you down in the middle of a river in my humble experience  😀

[Anonymous]

#13786

Great lot of written deduction going on guys and in hindsight it was pointing to high resistance . The factor for me was that you were getting fuel a sign that the ignition signals were there.  Injection relies on ignition cofirmation but there was just not the power suffient to charge the coil even though signals were occuring.  Multimeters and a good inductive pickup timing light are great tools for THAT BLOODY TASK. Shiney side up Paul

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