Guess this is for Ned, Ajays, crazy frog or any other TPS gurus.

Bike = 1992 K75S (TPS is a "clicker")

Managed to get involved in a bit of aftersales care for my ex bike...
Was running "ok" but needed a bit of setting up, from what I understand on the phone,
the only change that has been made is adjustment of the TPS as it was preventing the
throttle lever (between the throttle bodies) shutting

Now, only starts with a healthy handful of revs and fine at 5000, throttle off and head
literally fills up with petrol and bike belches smoke then dies.

Now I'm thinking the TPS here for 3 reasons:


1) It's just been adjusted and no issues before that

2) I don't KNOW for certain what it actually does so it's easy to blame it (yes I've
searched posts on here about it, I just don't understand them)

3) I THINK that it shuts off the injectors on throttle off to prevent backfires
- failure to do so would result in flooding right?



so to rule it out, we just disconnect it from the loom for now right?
(and worry about fixing it later) Other than that, any suggestions gratefully received.

My first recourse would be to to return to the person who gave it tha aftersales care and then with you standing there get them to set the throttle position switch up correctly using the BMW manual.
Regards,
K-BIKE

Sorry K-bike, maybe haven't made myself clear.

I sold the bike earlier this week and new owner is wanting help with fuel setup and has got this far, being a decent and honest chap I'm only too willing to try (especially since the wife is already spending the proceeds)

Problem is I don't think either of us "get" fuel injection (give me the old days when a bike flooded and you just kicked the carbs til it stopped)

I am following all the threads about the TPS and don't really comment on them.
I am a believer that the TPS was installed for a good reason and I will continue to use it as it was intended.
This is the device that tells the whole system if the throttle is open or closed. I personally enjoy the engine break on the K100 and it fits my riding habit.
When entering a curve, if I cut the throttle, I like the bike to decelerate without having to touch the brakes. The reason for shutting off the throttle could be gravel on the road and having to brake could be a good way to end up in the ditch.

To resume, if you have any problem starting the bike, reverse all your setup to factory default. It is very difficult to troubleshoot a problem when too many original setups have been modified.

CF

Fully agree.

If the only thing that has been changed is the TPS then it should not be running so rich as to flood at Idle, there has to be another reason.

The TPS only tells the ECU that the throttle is closed then if the engine is above 2000 rpm the ECU cuts the injectors from opening. There are three main reasons 1. to get better economy 2. prevent the anoying popping in the exaust (backfiring) 3. Helps to meet the emission standards set at the time of manufacturing. The best but unintended advantage is better engine braking.
If the flooding is happening on only 1 or 2 cylinders then get the injectors cleaned first as there could be some contamination holding the seats open.
Check the MAF (mas air flow) sensor, some call it the AFS (air flow sensor) there is a section on the site about it. If it is holding open then the ECUwill think that plenty of fuel is needed and will flood the engine.
The Temperature sensor will cause a rich mixture if it is faulty but not usually bad enough to stop the engine. When the temp is cold the ECU will make the mixture rich to help with starting and idle till the engine warms up to operating temp.

Bad connections in the wiring of either will cause the problem and more often than not the connectors at the plug points are to blame for bad connections and faulty signals to the ECU.

Just a few to help you get started

And remember Deoxit is your best friend when you have an older bike.

wedge wrote:Now, only starts with a healthy handful of revs and fine at 5000, throttle off and head
literally fills up with petrol and bike belches smoke then dies.

It might also be an idea to check the fuel pressure regulator?

Inge K.

Inge K. wrote:

It might also be an idea to check the fuel pressure regulator?

Inge K.

and the vacume line to it ...

bike belches smoke then dies

Just thought I would tip toe in here and mention smoke.
When parked on the prop stand oil can run into the cylinders and when starting will belt out smoke. Park on the centre stand and there will be no smoke and easier starting. Could be nothing to do with the TPS.
Ajays
What colour is the smoke? Blue[oil]/ Grey[water] or Black[petrol]

Black

charlie99 wrote:

and the vacume line to it ...

I did also first suspect the vacum line, as it`s running beside the TPS, but that would`nt normally give
so bad symptoms as discribed.
But if the membrane in the pressure regulator is stuck shut, it would.

Inge K.

Forget the TPS, unplug it for now, it will run OK without it connected. That will illiminate that. Try it.
I would then check the regulator to make sure it can return to the tank.
If this is OK then it most likely is a sticky injector. You can get these cleaned at a local garage for a nominal fee.
Vacuum tube [spring covered] next to the TPS will not give trouble, some of us have removed this and capped the aperture.
Process of illimination matey.
BTW
I bought my K100 from a chap that had had fuel failure when warmed up, he had it serviced by BMW. After trying everything I could think of and almost giving up I noticed the agents had routed the feed hose next to the water hose and as it expanded it pinched it and shut off the feed.
Pezi remembers this I am sure.
Ajays.

Thanks everyone so far, Bit of progress:

TPS eliminated
Probably not sticky injectors as it's suddenly all 3 at once

I'm going over to have a look Weds, return is the frontmost pipe to tank right?

Wedge,
Fuel feed pipe is the front of the fuel rail.
On here you can download the manual if you go to Crazy Frog's [Our Administrator] Download Page. Also much useful material there.
You can try my page here.
http://www.4shared.com/account/dir/CDKNGc7N/_online.html?&rnd=88 CLICK "SKIP ADS" when you get there.
Ajays

I got exactly the same problem with my K75.
For the last 3 weeks, one day it will start right away, the next day it will flood and refuse to start.
This morning I finally had the time to start to work on the beast.
As I have a good stock of parts, I started to replace plugs, wires, coils, ignition computer, Hall sensors, MAF, and FI computer.
I also removed the injectors to check the spray pattern as well as checking for any leaking injector. (I was pretty sure that they are not leaking as the system retains the fuel pressure for few days)
After testing, all these parts, I couldn't find anything wrong. All the original parts are back on the bike and it's running again. I am just anxious to try it tomorrow.
I kept the replacement MAF as the bike doesn't seem to give a puff of black smoke when quickly opening the throttle. Even testing the bike without the air filter, the spark plugs are still black. My next step will be to adjust the throttle body. It has not been done for years and this may be the problem.

Here is a picture on how I tested the injectors. I didn't want to repeat Club-C mistake and had the spark plugs hooked on the back of the bike. I plugged the fuel return line using a drill bit which in fact bypassed the fuel pressure regulator
Because of the return lines being plugged, the test was done under 63psi pressure(what the pump is capable of providing). If the injectors are not leaking at this pressure, they won't leak at 36psi.
With this setup, I was able to monitor the spray pattern as well as the spark at the same time.
I had to butt my cigarette during the test



Now, I was curious to know how the 3 cylinders is working with only 2 Hall sensors but 3 coils.
I believe that the ignition computer is 'guessing' the position of the the third cylinder according to the position of the 2 other ones. Does it make sense? If somebody has a better explanation, I would be happy to hear it.

CF (for one I am the one who is really puzzled).

Always assumed they were just for the ignition computer to fire the first spark then use the other trigger to work out how fast the crank is spinning and just trigger the other 2 sparks at 240 degree intervals.

What was the result of the injector test?

Yes, I think you are right. When I said guessing, I should have said calculating.

The injector test was perfect and I was amazed as the bike has over 330K on the clock.
About every 10K, I use fuel injector cleaner (which is mostly alcohol). I make sure that I will ride enough to empty the tank the same day and refill it in order to dilute the remaining of the cleaner.
After all these years and high mileage (Kilometers in Canada), the internal of the tank are original and I cannot see any residue of rubber on the bottom.
I have to say that I am please about this and still enjoy riding this bike even if it doesn't have as much power of the K100.

It's an original K bike!

wedge wrote:Thanks everyone so far, Bit of progress:

TPS eliminated
Probably not sticky injectors as it's suddenly all 3 at once

I'm going over to have a look Weds, return is the frontmost pipe to tank right?

Yes that is right the front pipe on the tank is the return line from the regulator.

Crazy Frog wrote:
Now, I was curious to know how the 3 cylinders is working with only 2 Hall sensors but 3 coils.
I believe that the ignition computer is 'guessing' the position of the the third cylinder according to the position of the 2 other ones. Does it make sense? If somebody has a better explanation, I would be happy to hear it.

CF (for one I am the one who is really puzzled).

The ignition is by two hall sensors one for cylinder No 1 and the other for cylinder No3 the ECU works out where to fire the No2 according to how the other two are working.

Crazy Frog wrote:I didn't want to repeat Club-C mistake and had the spark plugs hooked on the back of the bike.

Hey!!! What mistake?? I may eliminate alternatives, but never make a mistake!

Yeah baby, natural selection.............

Maybe I meant to burn off that vapor with a spark...

I can see the logic in getting rid of all that nasty vapour, you'd hate it to catch fire or something...

CF I am glad to see someone has the exact problem I have been dealing with for over a year...I have replaced everyhitng you have and checked the other patrs I did not replace and still have not had my bike running properly for more than 1-2 rides and my bike has only 10000 miles on it.

You may want to check if you don't have a short on the FI circuit keeping them open.
Positive is always applied to the injectors and pulsing negative is sent from the computer. If the insulation of the ground wire is bad and the wire is chaffing on the ground, the injectors will stay open.
I had not have time to check this yet.
Tonight I will replace the water temperature sensor and the fuel pressure regulator.
This is the nice thing when you have spares at home. You don't need to test it right away. If after replacing a part the problem seems to be solved, I will fully test the defective one to find the problem.
I don't have a lot of time to spend on the bike, and want to get it out on the road. Today summer arrived! This is the first sunny day (18 degrees) for over 7 weeks. We had the worst spring that anybody can remember. At least we don't have flooding, tornadoes or wild fire like in other parts of Canada.

Bert

I replaced every pieces of electronic on the bike and it still floods. Now I have to check every connections.
I swapped:
-ignition computer
-FI computer
-MAF
-coils
-ignition wires
-Water temperature sensor
-Hall sensors
-TPS switch

I checked the injectors and they are not leaking. The spray pattern is excellent
I also replaced the gas pressure regulator as well as the whole throttle body.
What do I miss?
I will resign myself to buy some Deoxit, but I will have to fork about $80 for it.
Why?
Only $25.00 for the DN5S-6N, but quoting Craig' site:

SHIPPING OUTSIDE U.S.A.
International shipping fees is a flat rate $40.00 by USPS Express Mail.

Aerosol sprays also involve hazardous shipping charges in addition to the above costs
Add the Canadian taxes, and a can of Deoxit will cost me almost $80.
The shipping charges would almost pay for the gas to go to pick it up in the USA (only 1,300km return - A nice Saturday ride)

cf you can get the deoxit in a small glass vial ....similar to nailpolish

maybe an electronics retailer is closer to you ?

Hey Bert, do you want me to post you a bottle? It's got to work out cheaper!

PM me if you want to go ahead with this. It won't be any trouble at all!

Thanks Blakey

I am checking with somebody living in Canada but right at the US border. In fact the border is in its backyard.
I really appreciate the offer.

Thanks

Bert

Bert I bought mine at a good music shop Long & McQuade. That's a national chain. You have one close? Or try someplace selling music sound equipt.

I think I have one about 5 min from my place.
I believe that they are close for renovation but will check it tomorrow.

I couldn't believe how much the shipping charges are for this product.

Thanks a lot.

Bert

Yes website says one in Dartmouth.

Exactly 4.5km from home and I drive in front of it everyday.

Hi Bert,
When yours floods have you checked the pulsing of the FI power rail is it pulsing more than it should or is it straight out on all the time and thereby holding each injector open full time. Use a 12 volt LED to test it. Options for why are if it is pulsing but much faster then something is convincing the FI computer that the engine is running much faster than it is and therefore it is supplying fuel for those high revs.

If it is on all the time I would suspect a false earth is appearing on the injector power rail.
Regards,
K-BIKE

Thanks to Club-C, I just bought a can of Deoxit for $28.
As they are renovating the music store, it took a good 15 min for them to find it. I am happy to say that I will join the club of Deoxit fans.

CF

Did God created the earth, then the human, then the BMW K motorcycles and then ....... Deoxit?

The K75 was not running for the last 2 days (flooding when trying to start). I had swapped every piece of electronic without any success.
Tonight I 'Deoxited' all the major connections and then, wwrroooomm! The bike started. rough at first but it then smooth out and it's running perfectly.
We'll see tomorrow, but it's looks good. (It's an off/on problem for the last week).
This is the problem when you have an intermittent problem. It can take a long time to find it and even longer to be sure that you fix it.

I toke two oxidized connectors and sprayed one with a regular contact cleaner then the other with Deoxit. After 2 min, the difference was amazing.

And the can is red, Blackey must like it!

yay !!!!..... good work bert and clubc

I always said right from the start when I joined the list DeoxIT is the absolute best contact cleaner there is, now if you just have the cleaner go and get a can of the DeoxIT Shield.
Regards,
K-BIKE