The reason I have a 16v one is I ordered one advertised as BMW K75 off Aliexpress. When tested it was incorrect and was for a 16v. I sent them an email and the kindly sent me another 16v one which I gave to a mate and kept one as a comparison.
Regards Martin.

MartinW wrote:It's possible that depending on it's quality the meat thermometer could be slightly out. How does the temperature readings compare between the digital and the meat thermometer.
Regards Martin.

Agree.  Most meat thermometers are thermocouples rather than RTD (Resistance Temperature Detector) style sensors.  RTD sensors are significantly more accurate and significantly more responsive than thermocouples.  You'd be better off using a special purpose instaread kitchen thermometer like this.

When you took your measurements, were you heating up the temp sensor or cooling off the temp sensor?  the better way is cooling off.  Heat the water to boiling with the thermo sensor submerged and then turn off the heat source.  Start reading the temperature sensor resistance values every 10°C as the water cools.

If you got the readings by going off the two pins and not the pin and the body of sensor I believe you have one for a 16v.
Regards Martin.

The problem is consistent to a 16v temp sensor in a 2v bike too.....

costellon wrote:Duh! Well that was 4 hours of my life that i'll never get back - but now I know.
Edit: Currently reading 2500 @ 24*c - corresponds nicely with the graph of values.
cheers

It would seem that you have remeasured the sensor correctly and are getting a correct value but I have to agree that the symptoms described does indicate a faulty temp sensor with infinite resistance at starting temperature. However, the temperature 'profile' obtained (post 44), even when measuring (incorrectly) across the sensor terminals, is inline with what you'd expect, it's just the values are double because the measurement is through both thermistors.
Having read through the whole thread it seems everything else is in order.

This leads me to the conclusion that the FICU is responding incorrectly at startup.

But a couple of questions:

1. Where and how did you measure the temp sensor? At the sensor itself, or at the FICU plug. On a K100 its #10 and #13. Don't know if it's the same for a K75 but by measuring at the FICU plug you are ensuring integrity of the signal into the controller. Make sure the wiring is in order and the contacts at the FICU are clean.
   
   
2. You indicate wet plugs after a failed start. What condition are they after a long run? They should be dry but if they're sooty then you've got over fueling across the range which could suggest you have a 4v temp sensor installed as Olaf has suggested.
   

Thanks for the replies.

I scrubbed up the sensor with a scotchpad - just under the plastic section. The numbers: 0280 130 032 (Bosch) were revealed. When I cross referenced the OEM part number off the BMW parts fiche (6131145917) the results confirmed that I do indeed have a TWO VALVE temp sensor in fact, I have 2 x 0280 130 032 - which were later superseded by 0280 130 069.
The FOUR VALVE temp sensor OEM: 13622242184 - is Bosch 0280 130 055.

I have now correctly tested my identical new and old temp sensors (0280 130 032 - the results of which were identical and can be seen below) and it appears that they are functioning correctly.


Robmack: I removed the sensors from the bike for testing and used the boiling water method, taking my readings as the water and sensor were cooling down.
Cheers

MartinW: I used the method that you suggested and measured the resistance between one conact pin and the brass housing (ground). However - I CAN measure resistance between the pins and from each pin to ground respectively - both the old and new sensors give the same results.
Cheers

Olaf: I understand what you are saying, and thanks - but by using the oem numbers of the K75 sensor off the BMW parts fiche to find the correct Bosch part numbers it would appear that I do indeed have TWO VALVE temp sensors.
Cheers

Holister: As you can see above I have now remeasured correctly (duh) and the results appear to be good. As I mentioned above, I removed the temp sensors for testing but I have also checked pins 10 and 13 at the FICU plug (which is spotless) and am getting the same reading as I get directly from the sensor - so it would appear that the circuit is functioning correctly.
In response to your 2nd question re the condition of the plugs after a run - they are dry and sooty.
Again, due to my cross referencing the numbers from the BMW OEM parts fiche - it appears that I have a TWO VALVE temperature sensor fitted.
Cheers

Another voltage drop check yet to to be conducted as I am limited in my ability to make noise here after 8pm.

Its important to note though that when the fuel return to the fuel pressure regulator hose is disconnected and directed to a bucket - the bike fires up first time - everytime - even with a partially discharged battery .....

Any other suggestions/ advice appreciated.

Thanks again guys

A thought bubble which just might be a quick solve or pointer at least. With two jumper wires (from battery positive to coil pins 15) your bike might start normally. It's a quick, easy thing to try.

I'm still confused about your fuel line in the bucket.

Is it the hose that runs from the injector rail that goes to the regulator, or is it the hose that runs from the regulator to the spigot on the tank?

Depending on which hose you are disconnecting, the pressure to the injectors could be very low, nearly zero, or much higher, possibly 2 bar or even higher than that.

It's possible that you have a problem with the check valve in the tank where the return line connects.  These valves have had problems that result in high fuel pressure and over fueling when starting.

Thanks for the replies.

Daveyson: Could you please explain further ?
Cheers

Point Seventy Five: It starts with the fuel return from the injector rack to the regulator disconnected and directed into a bucket (8mm hose that goses from the FI rack directly to the horizontal 90* spigot on the regulator). When I reconnect that hose to the FI rack and direct the return pipe to the tank from the regulator - into a bucket instead, it won't start - there are no kinks or cuts in the return to tank hose.
With the tank closed if I blow into the return pipe spigot on the tank - it pressurizes the tank and blows the air back out. If I blow into it with the tank lid open it doesnt pressurize and the air can be heard rushing into the tank. It's definitely a K75 regulator according to the part number, Vacuum hose on cyl 3 replaced with the proper flexi hose and has the coil on it - so that's not kinked or damaged. Fuel pressure measures ok. I'm currently waiting on a replacement reg from Holland - I ordered it so i'll fit it.
Cheers

Olaf: Perfect earth between sensor housing and negative terminal on the battery, no ptfe, one alu crush washer, no fiber washers
Cheers

Thanks again

Your engine will only start when there is no fuel pressure in the rail. 

You have confirmed that every part that has something to do with making the engine run is working correctly...

...And yet when you try to start the engine it won't start and the plugs are wet.  Sounds like flooding.  Have you tried cranking the engine with the fuel pump unplugged?

There is a voice in the back of my head now screaming that your ECU is not operating correctly.  It's the only thing you haven't confirmed to be working properly.  It doesn't seem to be injecting the correct amount of fuel when the engine is being cranked.  Is there any chance you can get a known good unit to try?

Point-Seven-five wrote:It's possible that you have a problem with the check valve in the tank where the return line connects.  These valves have had problems that result in high fuel pressure and over fueling when starting.

Nah, that was at the early K100, Costellon has a K75, no valve in the return.

Temp sensor is ok, let's focus on the wiring

The violet/green wire on pin 10 of the compconnector, put your multimeter on it on lowest Ohms, take the connector of the sensor, and measure the wire, must be very low Ohms.

Then, if the wire is good, plug the connector back to the sensor, measure between pin 10 and ground, should be around 2.5 kOhm at 20C.

And, just for the record, measure pin 13 to ground, must be low Ohms too.

If that's all ok, plug in another computer from any K75, see if that will do the job

"Could you please explain further"

 I was thinking about the possibility that the coils aren't getting full battery power, but these last few posts by Holister, Point seven five, and Arlina are shaping up best at the moment, I think.

Thanks for the replies.

Yet again I got in too late this evening to make noise and so am limited checking the pins/ connectors as kindly suggested by Arlina.

Point Seventy Five: With the block connector from the tank disconnected the engine fires up first time every time - until the residual fuel is expended. Same with the hose from the FI rack to the regulator disconnected.
By ECU I presume that you mean the FICU (Under the seat) ? Or ICU (Box behind the steering head) ? As far as I know the ICU units differ between the K100 and the K75. Regarding the FICU for a K75 - I may be able to borrow one off a friend that lives an hour away if he's up for it, I dont know if he has an ICU.
Cheers

Arlina: Readings are as follows: Sensor to pin 10 @ 13*c - 000.0 kOhms (Ignition on or off).
Sensor reconnected, Pin 10 to ground @ 13*c - 002.0 kOhms (Ignition on), 004. kOhms (Ignition off).
Pin 13 to ground - 002.0 KOhms (Ignition on), 000.0 kOhms (Ignition off).
Cheers

Daveyson: Cheers

Edit: Olaf: Cheers for confirming that, I just had a look at the parts fiche

Yet again, thanks to everyone for their time.

K75 ICU and FICU are not interchangeable....physically look the same..

ECU is the Engine Control Unit.  It's the one under the seat and is specific to the three cylinder K75.

Post up the part no thats stamped or on a sticker on the Fuel Injection Control Unit under the seat. Its K75 specific. It may have a Bosch or BMW part no on it.

You have successfully tested most of the things that can cause issues but I am not sure if you have tested the temperature sensor at the plug end which would reveal if there is a break in the wiring, not unheard of.

92KK 84WW Olaf wrote:You have successfully tested most of the things that can cause issues but I am not sure if you have tested the temperature sensor at the plug end which would reveal if there is a break in the wiring, not unheard of.

+1

We've asked for you to check the resistance across pins 10 and 13 of the ECU connector, and so far, you haven't responded.

You report that there is ground on pin 13, and continuity from the sensor connector to pin 10, but no confirmation of the resistance across them when the temperature sensor is connected.  It's such an easy thing to do it should have been done already.

Apologies for my not having responded since wednesday - I am a Mariner and have been at work - AT SEA - with NO INTERNET - once i'm over 15 miles or so from land I have no phone signal - and as a consequence - NO INTERNET. I cannot justify buying a sat phone/ link as its way down my list of priorities and anyway, I enjoy "cutting the cord" - that's part of why I do what I do.

Anyway, i'm ashore again until the next tide. Tonight I will be sailing and will not be coming ashore until next Saturday morning, so please exercise some patience regarding my responses or lack of therein. Thanks.

Olaf: In previous posts I stated that I tested both connectors from the temp sensor for continuity to their respective pins (sensor to pin 10 on FICU, sensor to pin E of temp control relay and pin 9 on temp relay to fuse 6) but I didn't state resistance.
I grabbed a pic of the FICU (see below) and noticed that it has a different bosch number to the one on my last K75 .... are all the K75 FICU's interchangable ? I'm wondering why some have different part numbers ....... doesn't matter.


Cheers.

Point Seventy Five: "I have also checked pins 10 and 13 at the FICU plug (which is spotless) and am getting the same reading as I get directly from the sensor" - from post 56 ...... I.E. Pin 10 to pin 13 on FICU @ 13*c - 002.0 kOhms (Ignition on), 004. kOhms (Ignition off).
Cheers

Thanks again, have a good week

As far as I know (and did) are all K75 FICU interchangable.

OK, scraping the bottom of the barrel, but the tides coming in, and it's a quick check. 

With the throttle in the fully closed position, you should hear a faint click at the rear of the throttle bodies when you slightly turn the throttle.

The throttle switch, between the throttle bodies and coils, could be sending a false enrichment signal to the fuel injection computer. Your brick might start if you unplug it.

Arlina: Thanks for that

Daveyson: I already reset the TPS, tried it whilst both connected and disconnected - no change. I then got another one off a K100 (same part no), fitted it, reset it and also tried that unit whilst connected and disconnected - no change. Tide's in, i'm out !
Thanks all the same.

Another little experiment I tried today. If I fit clean and dry spark plugs - it'll start first touch of the button with no throttle. Once I stop it and try to start it again i'm back to the original problem.

Yet again, thanks and have a good week/ weekend

costellon wrote:I grabbed a pic of the FICU (see below) and noticed that it has a different bosch number to the one on my last K75 .... are all the K75 FICU's interchangable ? I'm wondering why some have different part numbers ....... doesn't matter.

I'm wondering if the last sentence in the quote above is a conclusion you have drawn, or a query. Both Bosch and BMW change parts' numbers occasionally. In a BMW parts fiche, the superseding part number is indicated. In the fiche, two ficu units have been listed. The reason for changing the number could be from a tweak to its manufacturing, or an inventory re-configuring. Either part will work—as Arlina indicated. BMW has a long history of installing mid-production remodeling that is interchangeable.

If you have determined all the values measured at the fuel injection control unit plug are close to those outlined in the troubleshooting guide found in the Portal here, it's time to start testing the ignition control unit following the troubleshooting guide.

I'm also guessing it's something not important. Maybe it indicates which factory it's made in, I think the label says made in Spain.

They have a Bosch part no and a BM part no,...

Actually, 376 indicates it's an ex cop bike. There might be other signs of that, like bulky earth straps, one to the tank for example. The only brick I have with a fuel injection computer  with the last digit 6, Is an ex police bike. 

My k75 has a red sticker ending 332, yours, police, is blue.

You might see some signs that the bike was white, a net search of the Vin number might even show that it's original colour was police white. But you're right, that doesn't matter.

Can you tell us a bit about its history, and what colour it is now? . Do you have bare metal (paint scraped away) at all earth points?

I like the idea from Laitch that it's time to test the fuel injection control unit using Bert's guide. Your friend with the k75 would probably be more interested in trying your computer in his bike than the other way around, in case your brick cooked your computer.

What a week !!!

Yet again, thanks to everyone for their comments, advice and time.

I bit the bullet last Sunday night, logged on to Thom Hellbrekkers - kpartsholland website and purchased a 2nd hand FICU - it cost €80 including shipping to Ireland, not bad. I got an identical unit with the blue label - part number ending in 376.
My neighbours intercepted my parcel yesterday and gave it to me a few hours ago. I lit the fire in my shed, poured myself a nice cool tall glass of hefe Weissbiere .... delicious !
I then plugged in my replacement FICU/ Jetronic unit, turned on the ignition, pressed the starter button and the engine fired up in the first second. I stopped it, started it half a dozen times - perfect! To be sure I then refitted my old FICU, turned on the ignition and hit the starter - engine turned over but didnt start - not even a random fart - nothing. I put the replacement unit back in, ignition on - hit the button - fired up staight away - result!

I'm currently putting it all back together and will hopefully get out for a burn in the morning. It would seem that I have rectified the problem - I should be 100% sure by this time tomorrow.

Daveyson: The bike is indeed an ex police bike, earth straps all over the shop, two extra relays in the relay box and a load of auxillary wiring (which I removed when I had to replace the wire from the solenoid to the starter as well as some other melted wires - which I now assume damaged my original FICU).
The bike is painted Anthracite black and appears to have came like that from the factory - some small panels appear to have been repainted and going by a few scratches, the tail piece originally came off a red bike - probably to replace the police/ original unit - maybe someone replaced all of the panels and tank - who knows - I like it in black. All of the fixtures and fittings for the fairing parts were 100% original - it seemed that it was once well looked after and unmolested. Maybe it started out black and was perhaps used in its black livery as some kind of another Government/ emergency services/ law enforcement vehicle. It came with nice tidy City cases and is fitted with the original grey seat that came as standard on the black K75RT's from the early 90's. It looks pretty stock and reasonably presentable - except for the barn door sized screen that I fitted that I had left over from one of my past K builds (winter protection). I got the bike off a guy that got it as a non runner off another guy in Cork - there was no history with the bike and it was about 99% complete.

Tomorrow will tell all - but so far so good, I'm hoping to head to the Delphi Valley and do a few runs ... https://vimeo.com/653464912 (My old R80 GSPD "Panzer")

Thanks again to everyone - top class bunch of people - much obliged

Good to read
Now we're curious if the bike will run fine tomorrow

Bonus, good call. 

Don't turf the old computer just yet, some members here might be able to help fix it. I know nothing about computers but with forum help I got one of my fuel injection control units working again a few years ago. It only has one output I think.

Come over to Stradbally Fayre for the annual K Christmas Brunch 11am on 28 December. Already some Ks coming from Galway. Bring that FICU too.

Better run today, injector recond kit fitted, plug chop tomorrow, Mr. Lentinis timing experiments to be conducted after throttle body synch

The old FICU is already wrapped up and stashed for when I have the spare time to fix it.

Olaf: Very helpful and kind - but impossible, thanks all the same.

Sincere thanks to all involved for your time, patience, advice and kindness, moderators alike.

Peace and good will to all, never stop loving


Cheers

Glad you got it sorted Costellon. Did you find out if the different FICU part numbers for an ex police machine involves any “upgrade” ín performance? 

Cheers from Ros.

No "Upgrade" rOS, just matches the loom - truth never lies - call in for a cuppa and stick the capital "N" at the end of my costello right in front of your face - just for reference. I have biscuits

costellon wrote:..stick the capital "N" at the end of my costello right in front of your face .

Edited it! 

My Bad….