injectors not pulsing

[gsxrpig]

Hi Guys
Bit of history.
1990 K100lt in Australia.  Bought as a non runner but PO, said sprag clutch and fuel pump were Known faulty.
Cafe racer conversion, so have eliminated clutch switch and gear positioning but kept the neutral light with the help of the forum members.  Cahnges the instrument panel.
i have put in a new fuel pump as the last one had sat for many years and the mount had perished, holes in the tank and the usual problems.  So throttle bodies have been cleaned new pump and new regulator and new lines.  Also reconditioned injectors and new plugs.  Checked firing order.
SO was excited to put everything back together and ready to start the bike.
Fuel pump is pumping and bike is cranking well.
BUT the injectors are not letting fuel in.  Absolutley nothing through the new injectors.
I have downloaded Bert' troubleshooting guide...which is phenomenal but I cannot seem to get it to run.
Had a electrician friend come over today and we ran all the tests.
We have 12V at the red and green but can seem to get the negative pulse.
Checked all the grounds I can find cleaned and checked for continuity.
I am getting spark on all 4 plugs.
12v at red green injector when cranking.  BUT also 12V on yellow when cranking...only have a digital volt meter so it may not be correct to read the pulse here.
Ground to injectors at efi as test is close to expected resistance values.
i am trying to source an alternative EFI unit to test in the bike.
Any ideas would be great.  spent days looking into posts on here and testing various things on the bike.  Have swapped out relays.
I am out of ideas, maybe in all my modification i have missed something electrical in the safety features?   It seems to be getting 12v to injectors but not sending the ground pulse to allow them to open??
Any help would be great.  It is beer time here in Australia so I will be out of contact till tomorrow but i will continue to read Berts guide and hope someone has a light bulb moment. 

[Laitch]

Had a electrician friend come over today and we ran all the tests.
We have 12V at the red and green but can seem to get the negative pulse.

At which box on Bert's chart have you stopped? You can or you can't get the negative pulse. The but in that sentence is tending to skew its meaning for me.

[K1300S]

have you listened to the injectors (stethoscope or screw driver) and are not hearing the ticking?

"fuel pump is pumping" ...is that known because you can hear it or because you have actually seen fuel pressure at the fuel rail?


just confirming basics....

[gsxrpig]

Fuel pump is new and working have pressure at the rail but have not measured with a meter as yet.  Replaced the vacum hose and fuel lines at the same time as I put the new Reg in.
No ticking from injectors at all...new reco injectors.
Have taken rail off and no evidence of fuel getting through injectors when cranking.
Brand new plugs....dry as a chip.
I have 12Volt at Green and red when pressing the start button.
Also 12V on yellow and grey when pressing the start button.
I am unsure of how to test that pulse with the tools I have.  Hooking up an Led test light I do not get a pulse effect ??
Hooking my test light to positive on battery and connect to female pin 12 on ECU will provide green light before pressing the starter button...this stops until I release the start button.  to confirm that multi meter is measuring nothing at pin 12 then 11.75 volts when button is pressed.

[gsxrpig]

I can confirm that I am getting fuel returned to the tank from the regulator.
So I presume that it must be at suffice pressure to get past the new regulator.
I am still trying to find a gauge to confirm that 36psi pressure figure.
Thanks for the replies so far...really want to solve this issue and get this project completed.
I think I may have found a local guy with a running bike that is willing to swap his ecu into mine or vice versa and test that component.
It may come back to my initial wiring...removal of the instrument cluster gear indicator and clutch and choke switches.  I thought i had the all clear on that section. under a different post.  "USD fork swap"
The only other thing I will test now is I removed the warning light for the Temperature. As i am running a gauge now.  Hope with the forum I can find the problem.

[gsxrpig]

Just doing the tests on the temp sensor.
Only getting readings on ohms in the 20k setting.
at approx 30 deg the resistance is 3.79
If i the place it in boiling water the resistance goes steadily down to 1.03.
So resistance is changing with rise in temperature.
I only have a cheap meter and it won't seem to read in lower settings.
I have searched through and found some settings and the boiling temperature seems to still be a high resistance.
Even though the resistance is changing this still high reading may indicate a faulty sensor?
Anyone got any ideas..

[The Mighty Gryphon]

As far as resistance decreasing as the temperature increases, your sensor appears to be functioning properly.   As far as being in or out of the proper range, it appears to be reading a bit high if I recall.  That would result in an overly rich mixture because it's telling the ecu the engine is cold which isn't your problem as I understand it.

[Laitch]

That would result in an overly rich mixture because it's telling the ecu the engine is cold which isn't your problem as I understand it.

His problems seems to be his injectors aren't providing any fuel.

Please put the model of your bike in your profile. Is it an LT, or an RS?

[Laitch]

Install that functioning ecu that you can borrow and let us know what happens.

[The Mighty Gryphon]

His problems seems to be his injectors aren't providing any fuel.

That was my point.

[Laitch]

That was my point.

That was my reality check. :giggles  Now I've just been told it isn't April.  :yow

[kennybobby]

Swapping the fuel injection ecu with a known-to-be-good one is an excellent idea to help troubleshooting.  i think that would be called the Jetronic unit on the k75, not sure about your bike and when they went from Jetronic to Motronic, maybe you can check which you have. 

There is a big transistor in the ecu that provides the path to ground for the injectors.  If it is not switching then you get no fuel.  Swapping will let you know if your transistor circuit is defective e.g. bad solder joint, or if you are not receiving some sensor or timing signal into the jetronic.  So make the swap and report the result.

[gsxrpig]

As far as resistance decreasing as the temperature increases, your sensor appears to be functioning properly.   As far as being in or out of the proper range, it appears to be reading a bit high if I recall.  That would result in an overly rich mixture because it's telling the ecu the engine is cold which isn't your problem as I understand it.

Yes I agree.  I thought that if it was faulty it might send a signal to the ECU and prevent the bike from starting...by stopping the injectors from firing.  I am just hitting every angle I can at the moment.  It must be something simple but I can't seem to track it down at this stage.  I am a Jap bike man and the Bmw is very foreign to me.
LAITCH, sorry for the confusion...I did put the details in the opening post along with a bit of history to supply the forum with hopefully some bits of info which might help.
KENNYBOBBY it is a L-jetronic control unit and From my research people are saying they are very reliable, Maybe I am clutching at straws I don't know but worth a shot.
Plan on putting my unit in his functioning bike first and see if it works, the swap his into mine.   
I seem to be getting 12V to the injectors but like I said earlier I am unsure I am getting the pulse signal and am a bit unsure how to positively check with the tools I have.  I have got some noid test lights coming with a mate next week but want to try and get this bike going before then because I am an impatient bastard.
Thanks for the replies everyone and please keep them coming.  I will continue to put up my test results in the hope it will trigger an obvious or not so obvious answer from someone. :dunno2:

[Laitch]

Plan on putting my unit in his functioning bike first and see if it works, the swap his into mine.   

Fergawdsake, get it over with! You're interfering with valuable Netflix time. :giggles

Thanks for updating your profile. That way people don't need to backtrack to find out what's being worked on. People are eager to help but not so eager to Easter egg hunt. You still haven't answered my question about which box you were stalled at in Vogel's chart.

[gsxrpig]

Fergawdsake, get it over with! You're interfering with valuable Netflix time. :giggles

Thanks for updating your profile. That way people don't need to backtrack to find out what's being worked on. People are eager to help but not so eager to Easter egg hunt. You still haven't answered my question about which box you were stalled at in Vogel's chart.

Mate I am at the mercy of the bloke donating the use of his ECU...He isn't due till the weekend.  Don't worry if I had it. it would already have been tested.
2 more days wait.
As for the boxes...I am basically stalled at the pulsing negative at pin 12....As a couple of posts up I showed the results but as for pulsing I cannot be positive...  Positive no fuel is getting past with reconditioned injectors so to me i ain't getting that pulse.?
My only other thoughts is the safety features that I have eliminated are coming back to haunt me and telling the ECU not to fire the injectors.  But I would have thought it wouldn't crank at all.
Hence the posts and trying to feed as much info back to the forum so I am not misleading anyone.

[Laitch]

I am at the mercy of the bloke donating the use of his ECU...He isn't due till the weekend.

Thanks for the update.
If it were my bike, I'd turn my attention to something else and quit ruminating on this. There must be something else. The one upbeat factor about all this is that the previous owner was honest about the bike's condition.

You're thinking it must be something simple. I think you're right. Replacing a Jetronic is simple. You'd be far from the first to have it be the remedy, as kennybobby has already suggested. If you want to be obsessive, you can review all your connections, double check your results of having followed the instructions you were given here for the disabling of switches, and review the wiring diagram here for early K100RT/RS models until your friend arrives.

You could also just enjoy a walk in tropical weather and deal with it all on the weekend. My driveway is a sheet of sand-laced ice.

[gsxrpig]

Well if it's any bonus to you its hot as
 here....stuck at work ....and 2 bikes down and nothing to ride :yes

[Laitch]

Well if it's any bonus to you its hot as
 here....stuck at work ....and 2 bikes down and nothing to ride :yes

i can feel the warmth in your response. I've closed the damper on the woodstove. :giggles  Someday you'll look back on all this and laugh, maybe.

[kennybobby]

While you're waiting you can figure out the rubber clips and pin holding the L-jet in place, and pull it out for inspection.  Look at the bottom where the cover tabs are folded over and pressed into the slots--is there any evidence of tampering or marks from screwdrivers from previous owner's opening up the device?

i would agree they are mostly reliable electronics, but i have repaired hundreds of Bosch units over the years and found the biggest culprit is broken solder joints on the large transistor leads.  After years of vibration on the road the solder fatigues and cracks.  It is an easy fix.

[gsxrpig]

While you're waiting you can figure out the rubber clips and pin holding the L-jet in place, and pull it out for inspection.  Look at the bottom where the cover tabs are folded over and pressed into the slots--is there any evidence of tampering or marks from screwdrivers from previous owner's opening up the device?

i would agree they are mostly reliable electronics, but i have repaired hundreds of Bosch units over the years and found the biggest culprit is broken solder joints on the large transistor leads.  After years of vibration on the road the solder fatigues and cracks.  It is an easy fix.

Thanks for the feedback kennybobby.
It is a cafe racer so the ecu has been moved to the rear, but it looks in very good shape and has not been opened by the looks....until now :eek:
A few projects ago on an xv750 cafe I was doing I chased my tail for months until finally biting the bullet and replacing the TCI...which I was told very rarely if ever fail....switched it over and the difference was amazing.  Like you said,I think the age and heat of where it was located under the tank lead to its demise also.
I will resist opening this ECU until I get my hands on the test one tomorrow.  Although I spose it can't hurt to have a look....
Not much left to do on the bike except get it running then I can do a final wiring cleanup and test and tune then roadworthy it.  Might have to do some real work today :dunno

[gsxrpig]

 :musicboohoo: Well ecu swap complete.
No difference at all.
Put my unit in the donor bike and it never missed a beat.
Swapped his unit into mine and exact same issue.
Cranking but no firing.
I will pull the AFM and check the resistance readings again.
I have some Noid test lights on the way so that will confirm I am not getting the pulse.
Scratching my head big time here now.
Anyone with any ideas ...i will try any suggestions as I have none left.

[Martin]

Try pulling the injector and hook it up to a 9V battery to see if it works.
Regards Martin.

[gsxrpig]

Martin.
reconditioned Injectors....tested and pulse out of bike.
 :dunno

[Scott_]

Well, the ECU works in another bike, so that says the injector output is good.
Sounds to me that your bike is not getting the input to tell the ECU to fire the injectors then, which is confusing to me as I thought the input to fire the injectors and also energizes the fuel relay.

[gsxrpig]

Well, the ECU works in another bike, so that says the injector output is good.
Sounds to me that your bike is not getting the input to tell the ECU to fire the injectors then, which is confusing to me as I thought the input to fire the injectors and also energizes the fuel relay.

Confusing indeed.
Fuel relay is working, fuel pump primes and pressure  at rail.