Hi guys, 

First of all thank you for having me here. As opposed to working on K-series, I am new to the forum. I’m glad I get to join the discussion, but would first like to drop an issue here that I’m dealing with atm. I recently rebuild two identical K1100RS from 1995, and one is having trouble with the throttle. The electronics are identical on both bikes, and ignition loom is left untouched. Plugs, leads and injectors are brand new. 

One is running flawlessly, the other runs and idles, but upon full throttle the engine cuts and sounds like it’s not even igniting anymore, it just dies down. If i let go of the throttle in time it will start running again, but if i hold it too long it stalls. 

One interesting observation is when I unplug the TPS, the engine works without any issues. So I replaced the TPS, but as soon as i connect the  TPS again the problem is back. 

I’m a little in the dark here as I’ve replicated everything exactly the same on both bikes, and just one is giving me a hard time. 

Additionally when it idles theres a vague beat to the engine as if it’s running on 3 cylinders instead of 4. Checked plugs (all are sparking), checked injectors (all are clicking), and the headers are all heating up, just header’s 1 & 4 remain approx. 10 degrees colder than the middle two. 

Tomorrow I’ll be working on the bike so will try to eliminate more components from the suspect list, but if anyone has any ideas for what to try I’m all ears. 

Thank you in advance!

You have a break or partial break in one of the wires that run to the TPS connector block. Peel back the boot on the TPS connector and the defective wire might just show itself.

You can also do a continuity check if you unplug the ICU connector (the one under the headstock). The pins you are interested in are:

ICU pin 9 to TPS pin 18 (green/red)
ICU pin 2 to TPS pin 2 (white/blue)
ICU pin 3 to TPS pin 3 (white/brown)

Don't forget to give the wires a good wiggle while checking

Dai wrote:You have a break or partial break in one of the wires that run to the TPS connector block.
You can also do a continuity check if you unplug the ICU connector

It seems that Tim's Bricks are K1100—late models. They have neither of those items as far as my knowledge goes. The TPS function is handled by the Motronic Control Unit and the Motronic relay along with the throttle potentiometer, maybe. That's evolution for you.

Tim, have you used the diagnostic plug to track this problem on the ailing Brick?  If you have, which codes were generated? If you're unfamiliar with this tool, here is a locator diagram for the diagnostic plug and a fault code table. More experienced owners can help you out.

Has the fuel filter been replaced recently, it sounds like fuel starvation and a blocked filter.

Dai wrote:You have a break or partial break in one of the wires that run to the TPS connector block. Peel back the boot on the TPS connector and the defective wire might just show itself.

You can also do a continuity check if you unplug the ICU connector (the one under the headstock). The pins you are interested in are:

ICU pin 9 to TPS pin 18 (green/red)
ICU pin 2 to TPS pin 2 (white/blue)
ICU pin 3 to TPS pin 3 (white/brown)

Don't forget to give the wires a good wiggle while checking

Hi Dai, 

Thank you for your suggestion, we did indeed find a cable break in one of the wires going to the TPS. So the TPS is back to functioning as it should.

We do still have an uneven beat to the idle of the bike. every couple of beats it drops a beat and picks back up. Applying the throttle gives an even beat pattern though, would a simple TB resync possibly be the solution to that? They were synced before but all I can think of atm.

Alternatively I may replace injectors and plugs for good measure and peace of mind. We did notice some slight dark residue on the sealing rings of the injectors so I am suspicious that there was some paint on the connector ends of the fuel rail that came off inside the fuel lines.

Rick G wrote:Has the fuel filter been replaced recently, it sounds like fuel starvation and a blocked filter.

hi Rick, 

Thanks for your reply. The filter, pump and FPR are new so I hope it's not that.

Laitch wrote:

Dai wrote:You have a break or partial break in one of the wires that run to the TPS connector block.
You can also do a continuity check if you unplug the ICU connector

It seems that Tim's Bricks are K1100—late models. They have neither of those items as far as my knowledge goes.

Dai wrote:

Okay, then.
I'll just chop my lab coat into shop cloths, drink a hot shot of Terrazu, and await a blinding revelation.

Laitch wrote:hot shot of Terrazu

Wossat? Can I have some too?

Has occured to me that the emoticons could be misinterpreted - I was taking the p!ss out of myself.

Taking the piss out of yourself?

I've NEVER done that....

Dai wrote: I was taking the p!ss out of myself.

That's what the urologist said when caught hoarding specimen jars. I'm glad I consulted The Septic's Companion all those years ago. 

Swap the leads to the plugs with the good bike, see if the problem shifts with the leads.
By the way, ever cleaned the earthpoints?
Also, check the wiring/connectors on the coils (and clean them)

i've nothing to add as everything that I have thought of has been thought of and stated already but the above exchange had me pissing myself laughing - thank you.