Hey guys I'm back with an ongoing problem with my 85 k75. Just can't seem to pinpoint problem with the overly rich running engine.
I replaced the fuel pump and reg and am holding a constant 36- 38 psi fuel pressure. the engine ran fine for a while after replacement but when I started it the next day it ran rough and sooty. It seems better when the rpm's are above 3000 but it still is very sooty.
I have replaced plugs, water temp sensor, battery,cleaned grounds, hall sensors, intake boots. It seems every time I change something the engine runs OK for a period then acts up again!
What am I overlooking????

Soory it is an 86 k

Hi there, have you set up the air/fuel mixture screw? if not there is a procedure in the Haynes manual. If you did, then maybe your air mass meter needs adjustment, dont know if the down load section has information about it, but I´ve read about on the web, the relaxation of the vane´s return spring causes an over rich mixture.
Hope this helps
Best regards
JAP

Have you checked the the throttle position switch (TPS) located at the end of the fuel injector rail? How's the engine running if you disconnect it?



If the internal switch (#2) is shorted, it will tell the EFI computer that the engine is on full load and the mixture air/fuel will be enriched:
As the vane in the air flow meter will not be fully open, the MAF will not supply enough air to balance the mixture.
Disconnecting the TPS is worth trying as it won't cost you any money. The only adverse effect can be back fire in the exhaust when you close the throttle.

Further cleaning all the electrical connectors is always beneficial. Not just a spray with WD40, but some proper cleaning. These are one of the first fuel injected bikes and the sensor signals are very important. Any resistance in the contacts of the connectors will result in a false or off signal and the fuel is adjusted accordingly. Only when you are certain all your contacts are clean is it advisable to look at the individual components, otherwise you'll be chasing your tail. I'm with CF re the TPS, but don't forget/overlook the other connectors. I know its a rotten job, but once done properly it should last you a long time and you can exclude those pesky things for a long time.

I will write this up under another post on ABS but suffice it to say cleaning of connections is very important as Rene says it is a pain to do the full process as described by Caig in the DeoxIT information but doing it right will take time but it is the old do it right - do it once and having done it you can look forward to many years of trouble free connections.
Regards,
K-BIKE

Yes Pal,
I have the same model as yourself and Bert has hit it on the nail again.
Pull your plug on the TPS and see the results then...if sucessful then set your TPS below the first click so it doesn't activate. then you will not interfere with the top end range.

Downside, you may...get a popping in the exhaust but not a lot. Mine runs perfectly and the plugs look OK.
I have a glow plug to finally set the mixture screw.

Happy New Year . Ajays.

Also check the return ball valve thingy at the petrol tank return pipe, mine was rusted shut and i was using twice the petrol and running rough as the extra fuel had nowhere to go.

Once i removed it it ran fine