BMW K bikes (Bricks)

You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


fourwinds

fourwinds
active member
active member
Fuel pump can be heard running with ignition key on, before pressing starter button.

Starts & runs for a few seconds, then engine dies.  Fuel pump clearly RE-starts after engine dies.
This leads me to suspect that it is shutting off at some point & thereby causing engine to stop.

Following the excellent diagnostics & info shared here Smile ;
Have tested the connector to the FI controller.  Air flow meter tests OK via FI connector.
FI relay socket shows to be operating correctly.  Tested FI relay on bench, "clicks" when you put power to it.  4-wire connector to tank tests OK.

Tested for power at #6 fuse socket:  Zero volts left side, zero volts with starter button pressed. 
12v at Right side, drops rapidly to zero when starter button is pressed.

As a test, I put her all back together, jump a wire from positive terminal of battery to the left side of the #6 fuse, and she'll run all day.

The puzzle is this:  what is causing the fuel pump to stop running during the starter engagement cycle?



Last edited by fourwinds on Sat Apr 25, 2015 5:29 am; edited 1 time in total (Reason for editing : solved problem)

    

2Back to top Go down   87 k100 RT, intermittent fuel pump operation.  SOLVED! Empty 87k100 fuel pump issues on Fri Apr 24, 2015 8:51 pm

fourwinds

fourwinds
active member
active member
Did a bit more testing at lunchbreak...

additional info:

Bench tested FI relay, have voltage at "inner 87" post with no power to relay coil.
With power to relay coil, relay clicks and have power to "outer 87" post.
Seems to me that the FI relay is working correctly.


put FI relay in it's socket, have voltage at 4-wire connector the goes to tank.
press starter button and this voltage rapidly drops to zero.

    

Comberjohn

Comberjohn
Life time member
Life time member
All a bit hi tech for me but don't think the fuel pump should run until you press the starter button.
If it doesn't start, you'll hear the pump run for a few seconds afterwards. If it starts, the ECU then powers the pump. A short circuit somewhere, perhaps?
Phew! That's my technology limits reached. 😕
Take a seat. Some of the techies will be along shortly for a more detailed analysis.


__________________________________________________
Life is not a rehearsal.
2010 VFR 1200F DCT 
2010 R1200GS(gone)
1986 K100 Silver(gone)
2012 K1600GT(gone)
1984 K100RT Madison Silver(gone)
1989 K100LT Stratus Grey(gone)
1984 K100 Red(gone)
http://www.johnsdrivingschool.co
    

Inge K.

Inge K.
VIP
VIP
Sounds to me that the wrong type of relay is mounted.....switching output,
instead of double output.
When the coil isn't energized it should not be power at the output terminals,
when power is applied to the coil you should have power to both outputs.

A relay with switching output have the terminal designation 87a + 87b.
A relay with double output have the terminal designation 87 + 87.

You should have the later one.


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

Holister

Holister
Life time member
Life time member
That really sounds like the problem Inge...

But it begs the question, when did the problem start? Was this an existing problem when the bike was aquired or has it just started behaving in that way. If its just started then it may be something else.

The best relay to buy if you're going to replace is from EME
They're a later version and have diodes which prevent back emf from damaging ECUs. The older starter relay didn't have that feature. Also, don't buy a second hand.


__________________________________________________

1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
  87 k100 RT, intermittent fuel pump operation.  SOLVED! Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

6Back to top Go down   87 k100 RT, intermittent fuel pump operation.  SOLVED! Empty Fuel Pump Problem Solved on Sat Apr 25, 2015 5:28 am

fourwinds

fourwinds
active member
active member
Happy to report that it is indeed an incorrect FI relay.

Thanks to Inge K.!!

The relay operates perfectly, just is the wrong one for the job.
It runs the pump as soon as the key is on, then shuts off the pump during the starter engagement cycle. 

A bit of background:  bought the bike recently as a non-runner needing fuel pump replacement.
Knew I would have to complete that job, but was perplexed by the relay issue.


Not sure when or how the incorrect relay was installed, but have it sorted out now.

Thanks to all!!!

    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum