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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => Project Custom Motobricks => Topic started by: Jan on March 25, 2024, 12:16:19 AM

Title: No spark no fuel
Post by: Jan on March 25, 2024, 12:16:19 AM

Hi this is my first post and first time working on my 1993 K1100.

Little information before: I have a 1993 K1100 RS that I made into a cafe racer and decided to install the   Motogadget M-Unit I did all the wiring myself with the help on the OEM wiring diagram, I did NOT touch the Motronic unit or the harness.
After all the wiring is done I’m not getting spark/fuel injected, fuel pump works fine, the motronic unit is receiving power and delivering the power to the injectors and the coils, but at the moment of cranking the engine it doesn’t send the signal, I have power in all connectors as they should (I checked a lot of posts about injectors and coil problems) all my grounds are connected and the motronic case is grounded to the chassis. so my question is:


Is there any sensor that would prevent spark/fuel signal delivery? Like the HES, the Densit or, TPS?
I already have the stand switch and the clutch switch bypassed.

Title: Re: No spark no fuel
Post by: Laitch on March 25, 2024, 07:45:54 PM

What "the Densit", Jan—heat sink paste on the ignition output contacts?

Among other sources, interruption of the Hall sensor signal would definitely interfere with injection and spark, but so would having a dirty ignition output unit. Your "93 should have one of those. It's attached to the battery cradle. If its mating surfaces haven't been cleaned then smoothed with heat sink paste and its plug not clean, that could contribute to your difficulty.
From BMW's K1100 manual downloadable from a link at this page (http://www.motobrick.com/index.php?PHPSESSID=35849c13c60569325585f652866fb511&topic=11014.msg95717#msg95717).
(https://www.motobrick.com/gallery/4/1601-250324193508.png)

The Motronic 2.1/2.2 manual is downloadable from a link at this page (http://www.motobrick.com/index.php?PHPSESSID=35849c13c60569325585f652866fb511&topic=13441.msg119896#msg119896).

Title: Re: No spark no fuel
Post by: Jan on March 26, 2024, 07:46:08 PM

Hey sorry the Densit would be the air temperature sensor I named it wrong, the ignition output unit I checked and made sure it had a good contact but I will try adding the paste, and I did notice my hall sensor was kinda rusted I ordered one already waiting for it to arrive.
Thank you,  I will keep you updated 🙏

Title: Re: No spark no fuel
Post by: sooprvylyn on April 01, 2024, 03:29:43 PM

I don't t come on here often, but I hooked up an m unit blue to my k1100 and have no problems with anything. I'm happy to send you my super clean wiring diagram if you want it. Best to shoot me a text at 818.562.0831, or if not in the US hmu at nick@zox.la and I'll send it. Also happy to chat on it. The only thing I couldn't seem to get working was the keyless start, but might be a conflict w my Samsung phone.

Title: Re: No spark no fuel
Post by: sooprvylyn on April 01, 2024, 03:32:51 PM

Btw, mine is also a 93 k1100rs

Title: Re: No spark no fuel
Post by: Jhullmoto on April 30, 2024, 09:10:22 AM

Hey, looks like we’re having a very similar problem mate. I’ll be sure to keep you posted if we sort it out. Those manuals that Laitch suggested are great though. Good luck!

Title: Re: No spark no fuel
Post by: frankenduck on April 30, 2024, 03:25:11 PM

Here are the BMW wiring diagrams and fuses for a 93 LT with English labeling. Everything is the same as a 93 RS except there are added circuits for the radio, windscreen and map light.

https://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/kwiring/K1100LT.93/1993.K1100LT.Wiring.SLP.V2.0.pdf

Title: Re: No spark no fuel
Post by: frankenduck on April 30, 2024, 03:27:35 PM

Does it still have a side stand switch?