Author Topic: zero ignition response  (Read 4261 times)

Offline tracecovington

  • Curious
  • Posts: 2
zero ignition response
« on: March 12, 2018, 07:41:31 PM »
I've searched through this forum on and off for two weeks and could quite find the answer so I'm sorry if its out there and i couldn't find it. A couple weeks ago i started my bike up for a ride and it died on me which I attribute to it being too cold and and me not letting the bike warm up long enough. When I went to go fire here back up I got nothing from the start button. Lights still on and everything. I walked it back to the garage and my initial thought was to remove the ignition buttons and clean them and got nothing.


Then I thought maybe the starter. Tested that and it's good. When I jump the starter from the battery it turns over but I can't get the bike to start. I had a mechanic buddy come check it out and I have since replaced the ignition control unit, spark plugs, ignition coils, and the starter relay. I went through johnny's list of most common electrical problems and cleaned all those connections.


Any recommendations from here? Am I overlooking something ridiculous? again I tried my best to find other stuff on the forum so please If i missed it let me know.


Trace


1992 BMW k75
  • Utah
  • 92 bmw K75

Offline Filmcamera

  • ^ Quintessential Motobricker
  • Posts: 1434
Re: zero ignition response
« Reply #1 on: March 12, 2018, 08:20:12 PM »
Have you confirmed the fuel pump is running? The four pin connector is a very well known issue
  • San Jose, Costa Rica
  • 1991 K100RS 16v ABS1, 2018 Triumph Street Triple RS 765
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Offline The Mighty Gryphon

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Re: zero ignition response
« Reply #2 on: March 12, 2018, 08:25:13 PM »
Please forgive me, I am easily confused.

You say the bike won't start.  Then you say you jumped the starter and it turned.

When you say it won't start, do you mean the starter does not run when you push the start button?  Or does the starter turn the engine but the engine won't fire?
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline tracecovington

  • Curious
  • Posts: 2
Re: zero ignition response
« Reply #3 on: March 12, 2018, 08:31:16 PM »
So the starter doesn’t respond to the start button, but when bypassed and I jump the starter to the battery the starter turns the engine but the engine won’t fire up. Does that make more sense?
  • Utah
  • 92 bmw K75

Offline The Mighty Gryphon

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Re: zero ignition response
« Reply #4 on: March 12, 2018, 08:58:42 PM »
So the starter doesn’t respond to the start button, but when bypassed and I jump the starter to the battery the starter turns the engine but the engine won’t fire up. Does that make more sense?

Absolutely, the starter button does more than just spin the starter.  Among other things, it activates the fuel pump.  No fuel pump, no start.

Do you have a wiring diagram for your bike?  I would suggest that you spend some time studying the wiring of the starter button and the stuff it's connected to.  Try to understand what it does to start the bike.  Ask questions.  We will answer.  If you know what is going on, our troubleshooting advice will make more sense to you. 

For a beginning, find out where the start button gets power and where the power goes when you press it.  It goes down into the relay box where things like the load shed relay, starter relay, and fuel pump relay are activated to start the engine.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline The Mighty Gryphon

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Re: zero ignition response
« Reply #5 on: March 12, 2018, 09:34:15 PM »
My wiring diagram for the K75 is pretty bad and doesn't show what is going on in the switches and relays.  This is typical.

However, the starter button gets power from either the Neutral Indicator or the Clutch Switch.  The power comes into the right combination switch on the Black wire with green stripe.  If the neutral light is not lit, there probably isn't any power coming from it.

When the clutch is pulled in, power is sent to the start button, bypassing the Neutral Indicator.  This allows you to start if the transmission isn't in neutral.

The power that goes to the start button comes out on a black wire aith a yellow stripe.  This power goes to Start Relay, the Ignition Control Module under the front of the tank, and to the Jetronic unit under the seat.

Because the starter isn't spinning when the start button is pushed, I am inclined to believe the problem is in the wiring to and from the start button, and that is where you should look first.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline The Mighty Gryphon

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Re: zero ignition response
« Reply #6 on: March 13, 2018, 06:50:39 AM »
Have you cleaned the ignition switch.  They are a known source of starting and running whack.

Ignition Switch #4 Source of Whack:

http://www.motobrick.com/index.php/topic,9698.0.html
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline rbm

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  • Posts: 2281
Re: zero ignition response
« Reply #7 on: March 13, 2018, 07:27:59 AM »
Engine and Frame Schematic for K75 1990 onwards

Although geared towards the earlier K's, this document, Bike Won't Start, will help you to understand how the ignition system works because that part applies equally to early and later K-bikes.

  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline The Mighty Gryphon

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Re: zero ignition response
« Reply #8 on: March 13, 2018, 07:39:50 AM »
Rob, I wish there was a drawing that showed the switch and relay internals.  Would make following the logic of the wiring a lot easier.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Laitch

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Re: zero ignition response
« Reply #9 on: March 13, 2018, 11:04:06 AM »
wish there was a drawing that showed the switch and relay internals. 
There is a simplified diagram that includes elements like those in Vogel's K100 troubleshooting guide right about in the middle of it when you're scrolling through it. It accompanies the wiring diagram and links to other diagrams.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline rbm

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Re: zero ignition response
« Reply #10 on: March 13, 2018, 06:03:56 PM »
Rob, I wish there was a drawing that showed the switch and relay internals.  Would make following the logic of the wiring a lot easier.
I'm with you, Jim.  I don't like those square boxes they used.  The official BMW diagrams for this bike are no better - just the same square boxes.  I have to find time one day to sit down with a copy of photoshop and improve these wiring diagrams by adding pin numbers and internals.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline bizzaro

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  • co pilot
Re: zero ignition response
« Reply #11 on: March 17, 2018, 04:41:23 PM »
There is a PLETHORA of info on "no start issues" here at motobrick. And just as many approaches to solve the issue.  You need to start eliminating different components of your ignition system. Do you have lights?  Can you hear the fuel pump come on when you turn on the key?  You know the starter works, because you by passed it as stated............did you remember to turn the key on when you jumped the starter, and keep it in neutral? The list goes on. And there are no magic answers.  By process of elimination try and isolate the source of your problem. 


And for courtesys sake, for all the folks that took the time to respond, how about an update?
  • Vermont
  • Current:1994 BMW K1100LT Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
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 Bizz

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