injectors not pulsing

[gsxrpig]

Can we agree that your AC results for pins are within spec on Bert's chart 9,10, and 14?
Based on info you've provided, the only reading outside the chart's specification is the Pin 8 ignition module reading which is too high. Can we agree on that?
Is that "was getting nothing before??" a statement or question? It's an indecipherable statement in my book. I'm only concerned with what is happening now getting now.
"Which is giving me 12V but little AC under starter??" That is another puzzling sentence construction. I can't decipher that at all. It's too late for cafe cubano or I'd use that to translate. :giggles
"trying to trace the green/ yellow which turns into green black after the fuse." Where does the gn/sw wire go? Where does the ge/gr wire go?
It's an encouraging sign that you're getting a different reaction when something is disconnected, but using phrases like "reading on the high end of the chart" have no value to me. I need descriptions to be exact.

No we can't agree on pin 9,10 and 14 being in Bert's range.  The AC on pin 10 is .2. Not 1.5 to 4V.  I don't get that reading at all.
Now your confusing me.  I was chasing gn/ge and gn/sw!  I thought I was!
Sorry to confuse you Laitch.
Not my intention, pretty close to losing it with this bike.  The question marks is a habit I have of placing a particular"I got no idea left" emphasis on a statement.

[kennybobby]

Is your battery new or fresh?  When the light comes on when you let up on the starter button indicates to me that either the battery is weak or else the Ignition Control Unit is not working properly.

The ICU closes the circuit for the fuel injection relay that supplies the voltage to the injectors.  It should do that both during running and when the button is pressed.

Check to make sure you have the load shed relay and the fuel injection relay in the correct circuits.  Also the FI relay has 5 terminals but all the others only have 4.

[gsxrpig]

Battery is newly charged from the weekend.  Had my ute battery in there at one stage as well and it is new.
I am thinking ICU as well although I have no prove.  I think I have sourced one but will take a few days to get here.
The Noid light will only light upon releasing the start button.  At no other time.  And only with the temp sensor taken off.
The load shed relay and the fuel injection relay on my bike as well as the horn relay are all the same type.  All 4 pin and the wiring seems to to be correct to match.  Mine is a 90 model Lt so there may be a difference to earlier models.  I have tried swapping relays.

[gsxrpig]

 :clap:
Right.
First positive sign.
I decided to put everything back on and give it another attempt.  After days of stripping wiring.
I left the temp sensor off all together.
For the first time since getting the bike it fired.
Started but stalls out very quickly.
Reconnect that temp sensor and it will not start at all...not even close.
Disconnect again and it goes back to starting.
Man i needed that bit of inspiration.lol
To test what was happening I connected injector 4 lead to a noid test light.
That light is evident only when releasing the start button at no stage before or after.
So the injectors must be letting fuel past on release of the button and now the bike has fuel to the plugs.  But not enough pulse at the injectors to supply follow up fuel to keep it running.
Ideas anyone?

[kennybobby]

When i had an issue like this i wanted to see what is happening at the tip of the injectors--is fuel coming out and how much, a spray or a drizzle.  To do this you could pull the entire fuel rail with the injectors attached and arrange a pan into which they can squirt when you push the starter button.

Is the noid light measuring on the injector supply side or return side?  Is it just a 12V bulb grounded on one end with the probe on the other?

Your testing seems to show the green/red voltage is exactly opposite of the schematic.  There should be no voltage on that line unless the starter button is pressed or the bike is running, at least on the 5-terminal FI relay bikes.  Don't know if yours has a different schematic since you say it is 4-terminal relay.

[gsxrpig]

The noid lights are a sealed unit bridging both points on the injector and let you know when the injector would be opening.  so when the injector is getting a signal the noid lights up.
I will have to go check Green and Red at pin 9.  I thought it was testing 12V only on pressing the starter button.
Yellow and grey pin 12 is the ground supply.
After replacing the ECU on the weekend I have eliminated the ECU and thinking the signal from the Ignition may be to blame.
I bought a second hand Ignition unit last night and it will take a few days to get here.
The water temp sensor is obviously causing problems and I have had one on order since last week.
I don't understand the tests for the ignition control unit.  Pin 10 is a definite cause for concern.
It has 12V feed with ignition on.
But when doing the test from Berts chart when the starter is engaged the volts is .2.  Testing in AC as on the list, this should be 1.5V to 4V.
The Mighty Gryphon said the tests should be done in DC volts.
So I am stuck at that test.
For some reason the signal is getting to the injectors only when I release that start button.
Probably a bad thing but if I press the start button after the bike starts I can keep it running a bit longer as the injectors are spiking a bit more fuel into the system.

[The Mighty Gryphon]

First off.  In order to avoid upsetting Laitch anymore, this will be my last post on this thread.

As far as DC vs. AC readings.  Some of the terminals have both on them at various times.  I will defer to Bert's chart for his readings.  The reason for asking for the DC readings was to see what was happening to the 12V connection at pin 10 of the ICU.  A bad connection somewhere could possibly interfere with it and disrupt the operation of the ICU. 

As far as the temperature sensor, an easy test would be to get a 1/2watt resistor with the same value as a cold sensor and connect it between the sensor wire and ground.  That would simulate a good sensor to the ECU.

[gsxrpig]

Laitch does seem very angry.
But I think at me not you Mighty Gryphon.
You have been here from the start mate.  Don't give up on me yet.
Getting close.  Was good to hear it start.
That pin 10 is a problem I agree.
I am happy to do any test you give me.
On the DC side that voltage is there so I will try and trace it back wards again.
I will try the resistor as well.
Thanks for the help again.
I think Laitch has given up so I would appreciate your help still!

[kennybobby]

Would you be able to inspect/confirm the socket for your fuel injection relay--whether it has only 4 terminals populated or 5?

It's difficult to troubleshoot from a distance if custom modifications to a harness have been made and there is no schematic for reference.

At least you know the L-Jetronic is likely okay due to the box swap, so the issue is on your bike, and the weird action of the temp sensor and the 12V power is a good clue.

The noid light i have no clue how it works.  i would use a voltmeter on DC to probe between the backside of the injector connector and chassis ground.  The green/red wire terminal should read battery voltage during the time when the FI relay is energized, i.e. during starting and while running.  The other terminal with yellow/green should read battery voltage or something close to zero when the injector is firing.  The other place you could see this is on the right hand side of fuse 6.  Pull the fuse and measure DC volts between the right fuse socket and chassis ground, before and after pressing the start button.

You seem to have battery voltage during times when it should have none, and vice versa.

you are getting closer to solving this, hang in there...

[gsxrpig]

Kennybobby.
I have stripped the wiring from ecu to the injectors because something weird is going on alright.
I am getting 12v on Green red when cranking at the ecu and the injectors.
But also 12V on the yellow grey when cranking.
I put the probe on red and green and other probe on yellow and grey and I get a continuity beep. This can't be right can it?
i am close to finding the Gremlin I think.  Keep the tests and advice coming, please.
My model is an LT so I am pretty sure that the BMU, Horn and fuel relay are all the same and interchangeable.  Small relays.  Different form the RS models...I think. The fuel relay doubles up the green and red wire on pin 87.

It is bloody hard to troubleshoot from a distance, I am grateful for the help.
I try and put my results up so to keep everyone up to date.
red is pin 30.  green yellow is pin 86.  yellow brown is pin 85.


Just inspecting again.  Had 1 injector still connected so the continuity was going through that injector...Sorry got a bit excited.
I have no clue again..lol.
As for the 12V...I think that is normal, until the ecu sends the earth signal to open the injector.  But why that is not happening is the million dollar question.
I have gone right back to when i replaced the ignition.  Would this cause an issue?
Sorry above that should read Load shed relay, Horn relay and fuel injection relay.

[kennybobby]

Please explain what replacing the ignition involved:

I have gone right back to when i replaced the ignition.  Would this cause an issue?

[gsxrpig]

kennybobby, timezones are slowing my responses sorry.
I replaced the ignition with a simple 2 position switch.
Red is the feed wire.  turn ignition on to feed Green and also Grey/Blue wire.
I have eliminated the Grey wire as it feeds the Bulb monitoring unit which is also eliminated.
Very strange that the injectors only get earth pulse on release of the start button.
I have the Green from ignition switch directly feeding 12V to the kill switch,  then Green yellow feeding from the switch in the run position.  The start button is Black with yellow trace to feed ignition control unit and start relay.
Hopefully something stands out as incorrect!

[kennybobby]

i don't know if you made a typo or a wiring error when you say the black-yellow from the starter button goes to the IGNITION control unit and the starter relay.  Did you mean the L-JETRONIC?  which terminal pin of which control unit?

You left out mention of the wiring from the green/yellow from the kill switch--has that been changed?  It should go to pin 10 of the ICU, to the coils, to the fuel injection relay, and to fuse #1.

The output of fuse#1 changes to green/black and feeds the clutch switch and then back to the starter button.  The output of the starter button changes to black/yellow and feeds the starter relay and pin 4 of the L-Jetronic.  The starter relay coil is grounded by a brown/red wire to pin 11 of the ICU.

The fuel injection relay coil gets grounded by the yellow/brown from pin 7 of the ICU, at which point power is applied to the L-Jet pin 9 and the fuel injectors high-side.

The green wire from the ignition switch also runs to the load-shed relay which supplies power for the headlights.

i would make a sketch of what your wiring actually looks like and compare it to a sketch of what it should be--maybe then you can determine where the wiring error has occurred that is causing the weird action.

i would recommend that you sign up on Bert's k100 forum, there are a lot of blokes from aussie on that site--and someone close to home would ride over to help you for a pint of beer or two...

[gsxrpig]

On the wiring Diagram i have here.
Black /yellow goes from switch to ignition control pin6 and also starter relay.  Then from starter relay it goes to pin4 of the ECU.  I haven't changed that wiring from factory but wondered if I had used the right wire to connect to the starter button.
Green and yellow does feed fuse 1. then onto pin 10 of the ICU.etc. etc, But I have eliminated the gear positioning and clutch switches. So that 12V safety feed back to the starter switch from those 2 features is not there.
I simple supplied 12V full power via green from ignition to one side of my kill switch. I would think the bike wouldn't crank if I had not done that step right.
A question. When I have just disconnected the temp sensor will the bike normally start or is the ecu just blocking the injectors for protection or similar?
Same with the clutch and Gear indicator switches...Does the bike crank if these aren't in the correct position on a standard bike or does the bike crank but stop injector flow?
Yeah.  I have tried contacting a few locals, but It is a different breed to my normal bikes so don't know a lot of Bmw riders.  Beer supply is never a problem...in fact normally leaving before complete intoxication is the problem.. :falldown: [size=78%] [/size]

[kennybobby]

A question. When I have just disconnected the temp sensor will the bike normally start or is the ecu just blocking the injectors for protection or similar?
Same with the clutch and Gear indicator switches...Does the bike crank if these aren't in the correct position on a standard bike or does the bike crank but stop injector flow?

1. i haven't tried disconnecting temp sensor on L-jet, but on Motronic it won't start without a good temp sensor.  It may be true L-jet too, and your test results seem to point that way.

2. It won't crank if clutch switch is not in correct position on standard bike.

You will only get 12 V to the injectors thru the FI relay when you push the starter button (or the bike is running on it's own).  The 12V power will be cut when you release the button, but this is not the same as saying that the L-jet is grounding the yellow/green return from the injectors.  Absense of voltage is not the same as grounding.  The wire color is yellow/green right, you keep saying yellow/gray, which is very confusing?

Did you ever try the resistor test--to replace the temp sensor with a resistor, any value from 500 to 5000 should work.  One end connects to the violet-green going to pin 10 of L-jet, the other end of resistor connects to ground.

[gsxrpig]

Kennybobby,
Turns out my wiring was correct.  Sorry for all the confusion with colors. :clap:
The old girl lives! :2thumbup:
Thanks for the help.
Also
The mighty Gryphon
And even Laitch...
always hard to try and relay the info online, especially when frustration sets in.
Anyway we got there in the end.
If anyone is still reading and hasn't jumped ship.
Got the second hand Ignition unit yesterday....plugged it in and the noid light lit up like a xmas tree.  For the first time since I have had the bike that earth pulse was working.
Initially flooded out but got it going after the usual fixes and she fires up well now.
Smoked heavily but it hasn't run for 4-5 years so to be expected with all the work that has been done to it.
Need to balance the carbs and tidy up.
Incidentally that is with the temp sensor plugged in.
I will replace that when the new unit arrives, it smells a bit rich , which may relate back to that sensor.  Still a question mark on the temperature sending unit that I am about to look into.  Seems someone has been there before me with writing on the underside of the relay.

[Laitch]

Thanks for the help.

I think thanks ought to go out to Bert Vogel, too, because his troubleshooting chart was spot on. At reply #14 in this thread, gsxrpig was stalled by the lack of injector pulsing. He checked the AFM values and according to the chart, his values were not entirely out of line with a functioning AFM even though one was !5% lower than the lowest value. That could have been his mismeasurement given the circumstances. The problem AFMs in Bert's AFM chart had two or more skewed values. Bert's chart indicates the next step was to consider the Ignition Control as the problem but it took until reply #28 to start with it. Gryph was down with that unit being suspect too. When the pin #10 value was bad, that should have convinced all of us and stopped the backtracking.

This thread has taught me not to get sidetracked by the handwringing and weird language I'm reading; instead I should pay attention when an experienced wrencher like Bert Vogel has laid out a solid approach to the resolution of a problem. I'm pleased gsxrpig brought this to the forum in the way he did.

[The Mighty Gryphon]

Congratulations on sticking to it until you got it working.  You should be good for at least another 50-60,000 miles.  Many, many thanks for posting the final resolution.  There are a lot of threads like this where for one reason or another the original poster just disappears when things are finally working and doesn't give any feedback as to what finally got things working.

 :clap:

[gsxrpig]

The Mighty Gryphon I always get there in the end...just takes longer sometimes. :2thumbup:
I nearly didn't reply and if you go back through Laitch's comments maybe that will give you an insight into why some people may take some comments the wrong way and just not bother leaving a reply.  If I get help I will always be grateful and always pass on my knowledge to anyone that asks...unfortunately not much on Bmw's at the moment.
I agree, Berts chart is sensational!
However when I threw in a LOT of variables sometimes further investigation is required to nail a problem down.
Firstly I was assured by the PO that the bike was a goer when parked, something now I find extremely hard to believe.
I have ripped out the entire ABS system from the bike and there was always a chance something had gone wrong there to affect things.
Removed the BMU and indicator set up.
Replaced both switch blocks with Suzuki ones.  Removed the ignition and put in a kill switch.
Removed the instrument cluster along with the Gear position indicator and clutch safety features.
Not to mention have the entire wiring system out of the bike twice.
Any small wiring I had done may have come back to haunt me.
So checking and eliminating any issue in my wiring had to be done to ensure My work wasn't affecting Bert's chart.
Along the way I found issues with the AFM, temp sensor and a faulty Temperature sending switch but thankfully my wiring is good and not causing problems with any components of the bike.  I have learnt a lot about the Jetronic and the Ignition control unit.  The way the Germans do things is much different to the many Jap bikes I have worked on.
So would I do things differently...NO.
I am new to Bmw bikes so I don't have the contacts to randomly swap parts over with a mate.  And this build as every other one I have done is on a budget!  So randomly going out and replacing things before I am convinced they are faulty is just not an option.
Hindsight is a wonderful thing Laitch...sure if I had the ignition control box I would have tested it the same day as the ECU test.  Probably would have swapped the AFM as well if I had one.  But as crazy as you think I am, I am confident of riding the bike and not having issues with electrics down the road. 
I thank everyone that has commented on this post.  I for one don't think it was a simple one with all the things I have changed on the bike.
Great forum with excellent advice as well as excellent information at hand.
I hope as on other forums I am on, that I can help someone out of a bind one day.
Hopefully I get things tidied up soon and can get this project finished and get back on the road.  Been 8 months between rides.

[kennybobby]

Great to hear it.  That was an unusual problem that the flowchart probably couldn't pinpoint--a problem in the ICU was causing an issue in the L-Jetronic.  It looked like a fuel problem, but was really a spark-box issue. 

There's plenty of riders down your way in q'land, seems to be a great bunch to hang with.  Post up a picture when you get her done.

[gsxrpig]

done.

[Filmcamera]

Looks really good, I love the exhaust and that front end is just OTT

[jakgieger]

That is a very nice conversion.  I have been following the thread, but did not reply as my technical skill/patience was exceeded in the first post :hehehe .  I will say that perhaps if we posted pictures of our bike/selves initially, perhaps we would be able to aid the human connection/empathy.  We have all been mechanically stymied at some point.  Frustration aggravates a negative situation.  It seems we tend to objectify the person/situation, "what a wanker", with these modern impersonal communication styles.   

One of the reasons that I am here is that when I was 16, I built a truck from three trucks, with a punch, screwdrivers, hammer, box end wrench set, and a handy man jack.  I was able to do this with help from older and wiser mechanics with pointers as needed.  When I frustrated them, they did not tell me that I was a wanker.  They were able to communicate with a look, by not answering, by intelligent sarcasm, or by QUIETLY demonstrating the necessary actions.   I have buried four of those mechanics now.  They instilled a love of mechanics in me, and I attempt to pass this on.

Everyone who comes here realizes they have an older bike that will require some mechanical ability, maintenance, and patience.  Zalle had me wondering today :hehehe :hehehe , but if he sticks with it he'll figure out that a little tlc now will save much grief later!