Hi all,

Have a crazy bike at moment. Struggle to start. Put new plugs and fuel filter in and check every where for leak etc none 

Pump is pumping fine. When I take fuel.pump fuse out it will tick over but as soon as it goes back in if dies.

Maf flap is free and has been fine.

Does this sound like fuel pressure regulator?

Any help be appreciated as it's driving me crazy.

It sound like Daveyson's notorious pumpless ride. His solution was to replace the fuel pump relay. Here's a post he made on motobrick.com about it.

Aah I had never thought of that. 

I will have a look tomorrow and see what I can find out.

It was weird as yesterday it was running ok on way from work.

I have noticed lately that it has a surge at about 3000 rpm and give it some gas.

I also noticed it running richer than normal but assumed was because I was driving short journeys.

I will investigate and get back to everyone.

What year and model K would help. It sounds a bit like a problem with the temperature sensor or it's connector. When faulty it will run rich causing a failure to start from flooding, with the fuse removed it will start on the residual fuel in the combustion chamber. When the fuse is replaced it will often stall unless you manipulate the throttle to keep it running. There are values and procedures for testing the sensor on site. 
Regards Martin.

I'm new to the forum and BM's but have already noticed Martin's suggestion has fixed lots of flooding bricks,  the fuel relay a grand total of one,  so the temperature sensor is the odds on favorite. Hopefully it's just a dirty loose connection. On second thoughts the thread I started, to reproduce a problem, is not very useful. 

With a screw driver to the injectors, can you hear them ticking at idle?

My mate had a flooding bike due to a faulty ECU - https://www.k100-forum.com/t12241-flooding-injectors-open-but-not-pulsing-solved

The bike is 8valve rs 1987 year.

I will test the temperature sensor as well I thought that might be something to do.with it. More testing need.

Thanks all suggestions I suppose test one at a time.

Hi everyone.

Update. I check and substituted fuel injection relay with a couple I have and still no start/running.

So I turned to water temperature sensor.

I unplugged the connector and then plugged in an old one I had and earthed body on engine and it started and ran straight a way. Run for a  while and then lifted of sensor off engine and it died like was doing before.

Had a look at sensor in coolant tube and washer etc look a bit corroded. So it seems that this is the problem. 

I have ordered a new one to be on the safe side and will let everyone know what happens.

It started up pretty quick as well with my experiment sensor, so maybe it's been going for a while.

Check the wiring as well with meter and all.seems fine so must be the sensor or the seating on the coolant tube.

Thanks for all your help.

Try reading the water temperature resistance when the bike is cold. From the EFI module (female connector) pin 10 to earth. It should read 2.5K ohms at 20 Degrees C, and 300 ohms at 80 Degrees C.

If the sensor is rusted, it can increase the resistance so the module thinks the bike is colder than it is, so increases the fueling. Furthermore, lifting (your 'good') sensor off the engine will mean the resistance is infinite and the over fueling will be even worse.

Mike

When working with the sensor it is important not to apply thread sealant or anti seize on installation. The sensor relies on the gasket to stop it leaking and any goo can insulate the sensor from a proper earth.
Regards Martin.

Don't be tempted to use sealant around the sensor threads on installation. The sensor relies on the gasket to seal and sealant can interfere with it earthing.
Regards Martin.

And don't use ptfe tape either......

Ok thanks for the heads up. I will not put anything on the threads.

Hi all

Well I have finally got the new sensor in and bike runs like a dream.

I found out afterwards that the wrong sensor was in place which had been in bike for a number of years.

It was one.where you check the residence between the pins and not from one of the Pins and the body of the sensor.

I think maybe for later bike.

The bike seems alot more responsive and seems to idle better when hot.

Not sure what effect having the wrong sensor had as it was how I thought it was.

Very happy now it has been changed.

Just thought let everyone know in case they come across this issue.

Thanks for the posting the solution. It's a good finale.

I seem to also be suffering from flooding issues on my bike, looking to replace the plugs and temp sensor just to play it safe.
Came across a variety of offering for the part-no (61311459197) - Hella/FAE/Bosch/Vemo, etc - any recommendations?

I did try one from Aliexpress for around $10.00 Au. However it turned out to be from the later 16V Brick. I emailed them and they sent another 16v one free of charge. So my mate with a 16V brick has a couple of spares. I looked at the site a while ago and the add for the K100 temp sensor has changed. So either they have changed the sensor for one that works or it could still be the 16v sensor. I now have a spare in stock, so I won't be trying again.
Link https://www.aliexpress.com/item/High-Quality-Engine-Coolant-Temperature-Temp-Sensor-For-BMW-Motorcycles-K-100-K-75-K75-K100/32680512124.html?
Regards Martin.

MartinW wrote:I did try one from Aliexpress for around $10.00 Au. However it turned out to be from the later 16V Brick. I emailed them and they sent another 16v one free of charge. So my mate with a 16V brick has a couple of spares. I looked at the site a while ago and the add for the K100 temp sensor has changed. So either they have changed the sensor for one that works or it could still be the 16v sensor. I now have a spare in stock, so I won't be trying again.
Link https://www.aliexpress.com/item/High-Quality-Engine-Coolant-Temperature-Temp-Sensor-For-BMW-Motorcycles-K-100-K-75-K75-K100/32680512124.html?
Regards Martin.

They are locally available for ~11€ (for the Hella, and ~37€ for the Bosch), will just pick one up from here :-)