Hello
I have a serious problem with my BMW K100 RS , VIN 0018982K100RS. The fuel pump does not start when the ignition is switched on.
The first thing I did was check the fuses.
Turned out, that the second fuse is damaged counting from the bottom - 7,5A. I replaced the fuse
The pump is OK - after applying the external power supply it works.
The relay through which the pump is powered is not activated. After
switching on the ignition, the relay does not "click". The relay itself
seems to be functional, a characteristic "click" is heard when the
external power supply is given.
I replaced the ignition module, the one installed under the fuel tank, in the front part. Nothing has changed that.
Starter, spark on the the spark plug, indicators on the meter - work normally
After many tests it turned out that there is no minus from ignition control unit on the fuel injection relay.
At terminal number 86 fuel injection relay after switching on the ignition 12V (up to ground) appears, but there is no minus at terminal number 85. After switching the ignition on terminals 85 - 86 the voltage is about 0.1V, it is not enough for the contactor to close the contacts.
The cable from the terminals 7 ignition control unit to the terminals 85 fuel injection relay is not interrupted.
If I cut the cable and connect terminals 85 fuel injection relay permanently to ground, everything works normally. After switching on the ignition - the fuel pump starts working, I turn off the ignition - the pump stops working.The engine starts without a problem.
Can I leave it like that?
Is this something threatening?
What is the reason - Why the ground to the terminals 85 fuel injection relay comes from the ignition control unit?
One more question.
When should the fuel pump switch on?
a) after switching on the ignition
b) after switching on the ignition and pressing the starter button?
Thank you very much for the hints.
regards
Edi