K11 Owners Group

Offf · Joined: 16 May 2013 Posts: 6

I have 92 K1100LT. Recently fuel pump won't turn on when I switch ignition. (Yes, I have read another topics about this and cannot find my case).

Thus far:

Fuel pump itself working (tested with jumper).
Fuse is OK.
Relay should be OK... when I interchange same relays the relay works.
Now the weird part... when I interchange blue relay form ABS to black fuel pumo relay the relay activates and pump start working.
Using multimeter I see relatively low voltages on relay box (9..10V) Shouldint it be 12?

Actually I'm out of ideas what to test next.
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K1100LT 92

Scott_Anderson · Posted: Thu May 30, 2013 7:41 am Post subject:

Welcome to the forum......

On to your question.

What else is not working.
Are the fuel and temp gauges indicating anything with the key on?
Any of the inst panel lights lighting up.

Sounds like it could be your side stand switch acting up.
Try and bypass it.
_________________
Ride safe.

1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold)

Offf · Joined: 16 May 2013 Posts: 6

1. yes fuel gague reacts
2. no, temp gauge is not moving, i think it's because engine is cold

A.
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K1100LT 92

Offf · Joined: 16 May 2013 Posts: 6

Well... I'm getting somewhere

There is no ground on relays connector 85. It should be. When I wire ground directly to 85 relay acts and starts pump.
But it will not turn it off.

How long the pump should normally run after turning ignition on ignition?

How this relay is disconnected when fuel pressure is normal under normal circumstances?

A.
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K1100LT 92

Scott_Anderson · Posted: Thu May 30, 2013 5:34 pm Post subject:

The pump should normally run about 3-5 seconds.
After that the motronic keeps it off till it sees a signal from the hall sensors indicating that the motor is turning.

If the fuel gauge is moving then the side stand switch, and kill switch are most likely ok.

You could have a bad pigtail connector on the wires that come out of the tank. It is a "historic" or known failure point on these bikes.
What can happen is that the female side of the connection gets expanded and looses contact with the male half. The fuel pump feed will be the green wire, and ground is brown.

The relay ground is provided and controlled by the motronic.
_________________
Ride safe.

1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold)

Offf · Joined: 16 May 2013 Posts: 6

Cite from Motornic diagram:
"The relay ground is provided and controlled by the motronic."

So, the pump is OK, wiring is ok, relay is OK.
Pump is driven by providing ground to relay.
So it must be Motronic providing no ground to pump or the wire that goes from Motronic to relay.
Will check those later.
_________________
K1100LT 92

drikko · Posted: Fri May 31, 2013 2:40 am Post subject:

I don't have my K here to check but is the earth wire from the Motronic to the frame in good nick and screwed to the frame?
_________________
K1100RS '97
Laverda RGS 1000 '84
Jim Young Trailer Sailer 5.7M WB

DISCLAIMER:- Anything I say may have been when I was drunk so please don't take it personally.

'Bigamy is having one wife/husband too many. Monogamy is the same.'
Oscar Wilde

Offf · Joined: 16 May 2013 Posts: 6

drikko · Posted: Fri May 31, 2013 2:58 am Post subject:

I think there is, although as I said my bike isn't here to check. Hopefully someone else can chime in. I just have a vague recollection of there being one when I changed the battery a few months ago.

Could be wrong though.

I just had a look through the manual and there's no wire so I'm not sure what I'm thinking about sorry, ignore what I said, but it may be worth checking the earth pin on the motronic connector is earthed properly.
_________________
K1100RS '97
Laverda RGS 1000 '84
Jim Young Trailer Sailer 5.7M WB

DISCLAIMER:- Anything I say may have been when I was drunk so please don't take it personally.

'Bigamy is having one wife/husband too many. Monogamy is the same.'
Oscar Wilde

buckles · Posted: Fri May 31, 2013 5:49 am Post subject:

I am sure mine (1999) has an independent earth wire from Motronic to ground which is easy to see. I think it is standard.
_________________
Ian, owner of:-
1999 K1100 LT

Offf · Joined: 16 May 2013 Posts: 6

My Motronic is very similar to this one (socket on side)
http://www.bmwallparts.com/ECU-Bosch-Motronic-0261200402-e30-325i-525i-P2658831.aspx

cannt take picutre of actual unit, right now. Dint saw any separate ground wires on it.

A.
_________________
K1100LT 92

Scott_Anderson · Posted: Fri May 31, 2013 6:47 am Post subject:

There is a single ground pigtail that provides a static ground for the motronic case, has nothing to do with unit operation. There are multiple ground wires in the multipin plug for the operations of the unit.

Something else to check, as I just remembered that it "got" me last fall. Embarassed

I was having the exact same issue. Fuel pump acted like it was failed.

Ended up being the big motronic plug just not making a good connection. When plugged in.
Cleaned it with some contact cleaner and un-plugged/plugged it in a few times and all has been well since.
I applied some non-conductive grease to the contacts to help keep moisture out and hopefully prevent the issue happening again.
_________________
Ride safe.

1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold)