1989 K100 not starting - No pulse to injectors

[eran_k]

So i'm helping a friend with a 1989 K100, the bike was running until some time ago (although had starting issues all the time), then couple of weeks ago it wouldn't start anymore.
going over the famous diagnostic guide i found that there's no negative pulse reaching the injectors.
all pin values on the EFI plug seems ok except the resistance values of the injectors which are a lot higher the the table says they suppose to be.
testing between pins 9-12 i get
1 injector 18-20 ohms
2 injectors 12-16 ohms
3 injectors 10 ohms
4 injectors 8 ohms
also testing between pin 13 or pin 5 to battery ground gives higher then 0 ohms - i saw 3-6 ohms
there is continuity between each injector plug and pin 12
all connectors have been cleaned with contact cleaner and i made sure they are seated correctly
any ideas?
Thanks

[The Mighty Gryphon]

I would check the resistance of the injectors individually. 

[eran_k]

I would check the resistance of the injectors individually.

you mean check each injector on it's own, not connected to the harness?

[eran_k]

each injector give ~16 ohms

[rbm]

That's the correct value.

If you apply 12V across each injector while off the harness, do they pulse (make clicking sounds)?

[eran_k]

yes, they do
i don't think the problem is the injectors, i tested with a led across the injector connector and it's not pulsing, just blinks once when i press the starter and once when i leave it

[eran_k]

one more thing, i have an additional jetronic efi but it didn't make any difference, so i dont think the efi unit is the problem

[rbm]

According to the schematic I have, Pin 5 and 13 on the ECU are directly connected to ground. You should get a very low value.  3-6 Ohms is indicating a possible poor ground connection.  The ECU/injector harness is standalone and should have its own ring terminal for ground connection, as illustrated in this photo:


As you see, its near the 4-way connector that joins the ECU harness to the main harness.  Check this ground and ensure a good connection.  Also, did you verify the connectivity of the 4-way connector as I advised in your other thread?  Though the connector parts may mate together, the connections themselves could be missing.  Try cleaning the connectors and also slightly deforming the female connections to make sure that they engage with the male connections securely.

[eran_k]

i'll do that, for the sake of testing, can i connect these ring terminal directly to the battery ground? and see if the resistance is lower? if it's not it can point to some problem inside the wire itself.

[frankenduck]

i'll do that, for the sake of testing, can i connect these ring terminal directly to the battery ground? and see if the resistance is lower? if it's not it can point to some problem inside the wire itself.

Yes. Ground is ground.