85 KRT100 not starting, problem with fuel system

[pinhead]

this whole experience really dulls my opinion on the flying bricks vaunted reliability claims.  Since finding no reasonable approach or suggestion at what could be going on, I went to other blog sites for BMW bikes and also you tube.  What I found was that there was a plethora of brick owners experiencing similar symptoms as to what I have going on.  Crickets for reasonable suggestions, just the usual fuel pump, fuel supply issue.  A number of these guys, followed all the suggestions, ie replaced the fuel filter, replaced the fuel pump, replaced the injectors, replaced the spark plugs---nothing different!   What caught my eye on the you tube videos that on some there were 4 or 5 guys in the comments saying there having similar  problem and cant find an answer!  So the conclusion is it was the first year for BMW bikes fuel injection, it was over designed and little care was done in its design for longevity for ease of service and diagnosis.  And its another reason why these bikes are near worthless when they get old..........

[daveson]

Come on now, I think you've lost a valuable contributor for not giving much consideration to suggestions, which you continue to do. Bricks are reliable, durable, easy to service, and this forum has solved I think all the threads I've read, when the original poster cooperates.

The trouble shooting guide was a good suggestion, how did you go with that?

This thread reminds me a bit of those unusual cases where a kinked hose causes grief, then returns to its original shape under operating pressures, but then kinks again sometime after it's stopped.

[daveson]

Can any one give me a way I can diagnose this with out replacing or tearing down anything before I know what is wrong?

Yep. Testing the fuel pressure would be good, plus a lot of suggestions already mentioned.

[degoe]

I’d say. Go through the guide. It helps if you like troubleshooting.
If you don’t, maybe its better to bring it to a fellow kbike owner who does, and pay him some.

[pinhead]

One of the things about fuel pressure that is a misconception here is that if there is any fuel in the fuel rail the bike will start.  Clymer's gives the directions on depressurization of the fuel rail before attempting work and it suggests an adjustment to fuel regulator, than start the engine till it stalls and runs out of fuel.  That means the engine will run up to 0 pressure.  my bike has pressurized fuel in the rail and will not start meaning the injectors are not working which means its an electrical problem relating to all the myriad of sensors and controls that operate the FI system including the Hall Transmitter which signals both ignition and fuel injection timing.  As well as any wiring connection within these components.  What I was looking (or I should say hoping) to find is some one who had similar problem and identified a wiring connector or a component I could target and have a simple solution. Since I have a spare bike I can switch out a component with no cost.  The next thing I will do is check and follow all wires that affect the fuel injection starting with the wires going to the injector and work backwards.  when it gets to swithing all the possible components, I might stop at that point and give up on the BMW.  For the time I owned it, it was a very dependable machine, but not being able to diagnose, I have a problem with it.  And the Clymer's manual on the Hall Transmitter and fuel injector control systems says that it must be take to a shop for diagnosis and every expensive testing equipment is necessary.  I doubt very much if BMW dealerships even still have that testing equipment and if they did they would charge me more that what the bike is worth!

[pinhead]

Hall sensor?
Airflow mass sensor?
Connectors clean?

T
that is my suspicion also!

[degoe]

Fuel pressure is easily verified.
Just put a pressure gauge on the rail and see if its within spec.
Why its not injecting fuel could be up to any of the sensors (see guide) in the system (I don't know the inner workings of the regulation system) but they should all be giving proper voltages/resistances  upon checking (SEE THE GUIDE).
Theres also ways to check them online.
This problem solving consists of excluding causes, going from easy to hard. It can also be 2 problems at the same time, which makes it much more difficult. Therefore it helps to test all parts indovidually.

[pinhead]

Come on now, I think you've lost a valuable contributor for not giving much consideration to suggestions, which you continue to do. Bricks are reliable, durable, easy to service, and this forum has solved I think all the threads I've read, when the original poster cooperates.

The trouble shooting guide was a good suggestion, how did you go with that?

This thread reminds me a bit of those unusual cases where a kinked hose causes grief, then returns to its original shape under operating pressures, but then kinks again sometime after it's stopped.

Not much consideration for suggestions???  I have done almost everything suggested by this group, starting with the OEM replacement of the Coolant temperature sensor, removing the tank changing fuel filter(which I knew would not change anything, cleaning all connectors and inspecting wires under tank and elsewhere, etc.  So dont say I havent followed directions here.  but when some body tells me to replace the fuel pump or test the pressure, I kind of bristle.  The pump is putting out good pressure at the rail and I know it should start, maybe run poorly with the wrong pressure but will start if the injectors are operating.  But they are not and its an electrical or component problem.  Even with a dribble of gas in the fuel rail it will start. 
Yes the trouble shooting guide does give suggestions where the failure could be, but I think it leaves out the Hall Transmitter.  And, Yes you could be very correct that is could be a crimped hose or faulty wire connection somewhere,  but the question is where?  I cleaned all connectors under the tank and all wire connectors what were easily visible with the side covers and seat removed.  And these bikes are reliable and easy to service until you encounter what I have.  Go check out Clymers manual about the Hall transmitter or the Fuel injector control.  It tells you HANDS OFF, it can be damaged easily and the only place that can do it is a BMW dealership.  And one of the you tuber videos had a similar problem and replaced all kinds of parts finding out finally it was the Hall Transmitter, after which he sold the bike.   And I am not alone, its just that you dont hear from those who have experienced this,  they sell or junk bike after spending oodles of time and money replacing parts they didnt need.  Then they dont talk on this board anymore. 

[daveson]

I think the hall sensors are working because you have spark, but anyway the trouble shooting guide describes how to test them, or you can simply use a test light, described in a past thread.

There are many suggestions you haven't reported back on, for example from Laitch that a hose could be loose or split. How long does it need ether, etc. I asked if the fuel pressure regulator is leaking, it only takes seconds to check. Who knows, maybe that hose is loose, or kinked, or split, or blocked.

The pump is not putting out good pressure, that's the job of the regulator, it could be high or low, but you think it doesn't matter for starting, but it does. You say the injectors aren't working, are they ticking?

I don't know why you insist it should start without fuel pressure, mine wouldn't when I was messing around with that in the past.

[pinhead]

I think the hall sensors are working because you have spark, but anyway the trouble shooting guide describes how to test it, or you can simply use a test light, described in a past thread.

There are many suggestions you haven't reported back on, for example from Laitch that a hose could be loose or split. How long does it need ether, etc. I asked if the fuel pressure regulator is leaking, it only takes seconds to check. Who knows, maybe that hose is loose, or kinked, or split, or blocked.

I don't know why you insist it should start without fuel pressure, mine wouldn't when I was messing around with that in the past.

The Hall transmitter operates signals to BOTH the ignition and the fuel injection timing.  And the regulator would make no difference if there is fuel pressure at the rail.  I dont think your read my last comment completely.  The Clymer's manual gives the directions for depressurizing the fuel rail before maintenance.  An adjustment to the fuel regulator and then start the bike up and run it till it runs out fuel.  That tells you that the bike will run without the correct pressure until it runs out of fuel in the fuel rail.  I dont know what problem was with your bike, but if it didnt run and had ignition and fuel at the fuel rail, it should have started, albeit maybe poorly.  The only condition where it maybe might not is where the ambient temperature was cold below 50 degrees or less and the fuel injection control was not boosting the injector opening period time for startup.

[daveson]

I just read that part of Clymers, describing how to open the regulator valve to relieve the pressure. The rail doesn't run out of fuel, simply the pressure is reduced.

So you see the pressure is held high by the regulator, not the pump.

The second method (yes I see your point, it's a little ambiguous) is to disconnect the pump and run the engine until it stops, this is under the heading for depressurizing the fuel system, so you see when the pressure drops, the bike stops. The rail won't be empty, with no pump cirulation, fuel will flow into the rail under the pressure of gravity.

[Laitch]

Members of Brick forums from all over the world have replaced Hall Effect sensors successfully regardless of warnings. There's a test to check them in the troubleshooting guide.

There should be better things to do with precious time than waste any of it resenting unproductive advice earnestly given to help fix a motorcycle that's unresponsive to repair efforts. If this motorcycle were mine, it would be parted out or donated to a vocational school. I wouldn't sell it to anybody unwilling to see it as the clapped-out failure of engineering it is.

[daveson]

Nothing wrong with a bit of biffo every now and then to keep you on your toes.

[pinhead]

Members of Brick forums from all over the world have replaced Hall Effect sensors successfully regardless of warnings. There's a test to check them in the troubleshooting guide.

There should be better things to do with precious time than waste any of it resenting unproductive advice earnestly given to help fix a motorcycle that's unresponsive to repair efforts. If this motorcycle were mine, it would be parted out or donated to a vocational school. I wouldn't sell it to anybody unwilling to see it as the clapped-out failure of engineering it is.

Replacing them is so different from testing them.  The Clymers manual gives that procedure.  so what you are saying is the Clymers publication is wrong when it says there is no way for a shade tree mechanic to fully test the Hall transmitter?  the Trouble shooting guide is a great source of information and I wish it had been given to me long ago when I started my diatribe.  But its testing means are static testing only and given the cost of the BMW testing equipment, I believe they can do dynamic testing.  Like the difference between setting contact points statically or dynamically using a timing light.  And my failure is intermittent as I have gone to great length to explain.  And a dynamic test would give a failing unit where a static test may not. For example the timing light variance in signal location and give a good diagnosis of problems in your ignition system.   Not to mention it is very easy to damage the Halls transmitter.   And regarding resenting unproductive advice, I think it is helpful to the whole blog and to the giver of unproductive, or more appropriate, illogical advice to correct them, but in a nice way,  so everyone results in a better understanding.  When I first started this whole thing the first response I got was fuel filter.  Having experienced plugging fuel filers, having worked as a patent examiner in fuel injection control systems, I knew it couldn't be that.  I politely responded that I didnt think it was that.  What I got was rude response, "How do you know without trying?
My most sincere apologies for suggesting a free way to start troubleshooting. I will ignore this thread henceforth." 

[pinhead]

I just read that part of Clymers, describing how to open the regulator valve to relieve the pressure. The rail doesn't run out of fuel, simply the pressure is reduced.

So you see the pressure is held high by the regulator, not the pump.

The second method (yes I see your point, it's a little ambiguous) is to disconnect the pump and run the engine until it stops, this is under the heading for depressurizing the fuel system, so you see when the pressure drops, the bike stops. The rail won't be empty, with no pump cirulation, fuel will flow into the rail under the pressure of gravity.

No I dont believe the regulator holds pressure high, it reduces it.  Pump puts out over 65 PSI pressure at fuel rail is 38.   One might ask why not make a pump put out the correct pressure?  Its because you may need the high out put when heavy demand for fuel occurs, ie riding up a steep hill on a freeway.  At that point the pressure regulator relaxes its stifling of the pressure since a significant pressure drop in the fuel rail as occurred due to the demand for fuel.  As the volume of output of a pump increases, the pressure it puts out drops.  But at the same time it is not desirable to have 65 psi at the fuel rail and fuel line since it is a danger at such high pressure and can blow lines and fitting much easier than the 38 psi.   
But  I dont understand your either point, doesn't that mean it will run with abnormally low pressure?  And when gravity stops supplying fuel, the bike stops running right?  Isn't that 0 pressure.   Then what is the point in my case of testing for pressure when there is ample fuel at the rail?

[Laitch]

so what you are saying is the Clymers publication is wrong when it says there is no way for a shade tree mechanic to fully test the Hall transmitter?

You're stating that.


I'm stating there are tests for Hall Effect sensor function in the troubleshooting guide and in BMW's diagnostic test manual that many have found helpful, and that it is possible for somebody—shade tree-, fruit tree-, or shed floor-mechanic—to replace Hall Effect sensors if preconceptions and ego are abandoned, and the ability to carefully follow the instructions of somebody who has done it successfully is deployed. Taking risks to do some of these esoteric procedures isn't for everybody, especially when a sense of futility regarding the outcome will likely accompany the work.

[pinhead]

You're stating that.


I'm stating there are tests for Hall Effect sensor function in the troubleshooting guide and in BMW's diagnostic test manual that many have found helpful, and that it is possible for somebody—shade tree-, fruit tree-, or shed floor-mechanic—to replace Hall Effect sensors if preconceptions and ego are abandoned, and the ability to carefully follow the instructions of somebody who has done it successfully is deployed. Taking risks to do some of these esoteric procedures isn't for everybody, especially when a sense of futility regarding the outcome will likely accompany the work.

You can be very insulting although sometimes you offer good advice.  Are you sure that the BMW test equipment is not dynamic?  Did you comprehend what I said about dynamic vs static testing?  I would like to see the BMW's diagnostic test manual if BMW produces it.  Is there a link for this?

[daveson]

Ok let's assume for a minute the pump is producing 65psi and the regulator reduces it to 36psi. You removed the hose from the front of the fuel rail and noticed fuel was pumping out. The fuel only came out a few inches. If it was at 65psi the fuel would have been spraying say two meters away and the hose would be flipping and flopping all over the place. It wasn't, it was just a lazy flow of fuel, way less than 36psi, like water coming out of a garden hose.

The point of the ether test is if it's a no go, but starts with ether, then you can conclude that your bike is getting spark but there is a fuel problem.

The pump includes a pressure relief valve. It's purpose is to open in case of a total blockage somewhere in the system. When there is a total blockage the pressure relief valve opens at 65psi, if there was no pressure relief valve, the pressure would continue to increase until something breaks.

There has been at least one thread in the past where the return valve in the tank was blocked, therefore the pressure increased to 65psi. The computer mainly supplies the amount of fuel by adjusting the length of time the injectors are open. It assumes the pressure is 36psi at the most. In this case the computer had no way of knowing that the pressure was 65psi so the engine was hopelessly flooding and the bike wouldn't start. He cleaned the valve which solved the problem.

[degoe]

The pump is able to produce65 psi given that there is enough backpressure. The valve is there to enable flow back into the tank and gives a backpressure of 35psi. So the concept of it reducing pressure is incorrect. Technically you could tighten the spring in the pressure valve until the backpressure reaches 65psi and fuel blasts out of the injectors. The amount of fuel being injected is regulated by chaning the injector open time. If the pressure is out of spec then the amounts being injected will also be incorrect, or one would have to reprogram the injector

[Past-my-Prime]

I have a 1985 KRT100 that turns over but does not try to start.  With a little starting ether in air intake fires up very briefly so its not getting any fuel.  I have looked a little on fuel pump replacement and have seen a number of you tubers replacing fuel pump which was not the issue.  Can any one give me a way I can diagnose this with out replacing or tearing down anything before I know what is wrong?

Sometimes after a longish problem solving journey, it’s helpful to go back to the initial problem. You noted that “it would start and run briefly with ether” and concluded that it’s not getting fuel. Parts of this ongoing discussion identified that inadequate fuel supply, because of lack of fuel pressure, might be one cause. Other parts indicated that perhaps the fuel injectors aren’t opening or not at the correct time because of a faulty signal either from the Hall Effect sensor of the fuel injection computer. If this were my conundrum, the easiest test would be to see what the actual fuel pressure at the fuel rail is. A faulty fuel pressure regulator would therefore be diagnosed. (Or, I suppose, faulty fuel pump/filter apparatus). In the alternative, changing the fuel pressure regulator would, if it worked, tell you the problem.

Once you know that fuel supply before the injectors is intact, the next step logically in my mind would be to see why the injectors aren’t supplying that fuel into the engine.

I can only approach complex systems by breaking them down into constituent components. Otherwise I find myself going around in circles.

[Laitch]

So the conclusion is it was the first year for BMW bikes fuel injection, it was over designed and little care was done in its design for longevity for ease of service and diagnosis.  And its another reason why these bikes are near worthless when they get old..........

To restate:
If I believed a motorcycle of mine fit the description of this motorcycle by its owner, resolution of the situation would be parting it out, donating it to a vocational school or selling it for salvage. I wouldn't sell it to anybody unwilling to recognize it as the clapped-out failure of engineering it is. If they didn't recognize it as that, they'd need to pretend they did. I had a 1956 Nash Rambler Airflyte station wagon that qualified for this category when I was a kid. After it had a brief and smokey career with me as a musical instrument- and musician-hauler, the washtub bass player in the jug band used its roof as a drum with ball peen hammers as drumsticks during a music festival on a college campus. After that, I sold it for $20 to a metal scrapyard.

[pinhead]

Sometimes after a longish problem solving journey, it’s helpful to go back to the initial problem. You noted that “it would start and run briefly with ether” and concluded that it’s not getting fuel. Parts of this ongoing discussion identified that inadequate fuel supply, because of lack of fuel pressure, might be one cause. Other parts indicated that perhaps the fuel injectors aren’t opening or not at the correct time because of a faulty signal either from the Hall Effect sensor of the fuel injection computer. If this were my conundrum, the easiest test would be to see what the actual fuel pressure at the fuel rail is. A faulty fuel pressure regulator would therefore be diagnosed. (Or, I suppose, faulty fuel pump/filter apparatus). In the alternative, changing the fuel pressure regulator would, if it worked, tell you the problem.

Once you know that fuel supply before the injectors is intact, the next step logically in my mind would be to see why the injectors aren’t supplying that fuel into the engine.

I can only approach complex systems by breaking them down into constituent components. Otherwise I find myself going around in circles.

  Yes, I agree to a simplified and strategic approach also rather than making immediate assumptions and attacking a specific area with no real indication that that could be the problem.  But regarding the fuel pressure, I am sure there is fuel supply at the fuel rail since I removed the fuel line at the rail, hit the starter and it gushed fuel out.  Now I know if still may have a problem in that its not the correct pressure but I know there is fuel there.  And according to the Clymer's service manual for this bike, the fuel rail can be drained by starting the bike and running out of fuel completely in the fuel rail.  In addition to that, a respondent gave a good suggestion for listening to the injectors for clicking.  And there is none.  So I know now that the injectors are not working and I am going to start with all the electrical lines that affect the operation of the injectors.  I have already cleaned all the connectors, under the tank and visible anywhere else.  I will check continuity for the wires next and then, go down the line to components that affect the operation of the injectors.  I am loath to start replacing components until I looked at the more simpler causes.  But I have a suspicion of the Hall Transmitter or the MAP. 

[The Mighty Gryphon]

I am loathe to post on this thread, but here goes:

Have you pulled the injectors, rail and injector wiring off the head and confirmed that the injectors are spraying fuel when the engine is cranking?  I suspect they are not.

There is a signal from the Hall sensors that commands and synchronizes the injector operation to the rotation of the engine.  That signal to the engine control unit may be missing. 

Then, there is a transistor in the engine control unit that opens the injectors by completing the injector circuit.  It is possible that the transistor may have failed.  If that is the case, you would probably be better served by just replacing the engine control unit. 

If you think you might want to check these items I can give you some ways to test, but first you should confirm whether or not the injectors are squirting fuel.