UK Buell Enthusiasts Group
https://ukbeg.com/forum/

Xb12s 2005 fuel pump runs constantly with ignition on, engine off
https://ukbeg.com/forum/viewtopic.php?f=8&t=24063		 Page 1 of 1
Author:  Buelladen [ 22 Sep 2019 09:43 ]
Post subject:  Xb12s 2005 fuel pump runs constantly with ignition on, engine off
Hi all
I am posting here after already having received lots of help from Pash, who is always there when im in trouble.
Summary below.
After relocating slightly my fuse box and ecm, which were already relocated under airbox and running fine, now fuel pump runs constantly (not just priming) with engine off and ignition on. Bike starts and idles fine. Not tested on road.
At Pash's suggestion i check with voltmeter the pumps connector (pump side and ignition side).
Pump side i have no shorts (checked touching both frame and negative pole of battery).
On ignition side of the connector the only wire the blips when touching frame is the black one (which is supposed to do).
So usually if pump runs constantly it means the yellow/brown wire is chaffed and grounded, either at pump side or ignition side, but mine seems NOT!
I went on and check with voltmeter the connector ignition side while ignition is ON.
keeping the neg on the black wire,
Grey wire shows 13v, yellow/red wire (fuel sensor) shows 12v, Yellow/brown wire (pump signal from ecm) shows zero.
Is this normal? This is the reading a few seconds after switching key on, just the time to grab voltmeter and position the electrodes. This would be the time when ecm primes the pump or slightly after that as i am not fast enough after i switch the keys on to position the electrodes on the connector.
If it is NOT normal, and say i have accidentally cut the yellow/brown wire at the ecm side, would that not cause the pump to die rather than being constantly on?
Another question is, diagram of pump's connector shows what is wire 1,3 and 3, but the wires are 4! What is wire number 2 grey supposed to do, the picture of a pump pulled out frame shows that both the grey wire and the brown/yellow wire attach to the pumps motor. Has the pump motor got 2 positive wires???And the last wire (red/yellow) is the one which goes on fuel sensor. So what is the grey not on diagram? Also they call the lowfuel sensor wire "GY/O" (GREY ORANGE) mine is red and yellow??
last question, Could diode or relays malfunction cause the pump to run all the time? I have not checked these and not sure how to do it.

Cheers

Attachments:
FB_IMG_1569128267774.jpg
FB_IMG_1569128267774.jpg [ 33.11 KiB | Viewed 1459 times ]
Screenshot_20190922_003636_com.android.chrome.jpg
Screenshot_20190922_003636_com.android.chrome.jpg [ 879.19 KiB | Viewed 1459 times ]
IMG_20190921_230500.jpg
IMG_20190921_230500.jpg [ 1.57 MiB | Viewed 1459 times ]
Author:  Jazzbutcher [ 22 Sep 2019 13:42 ]
Post subject:  Re: Xb12s 2005 fuel pump runs constantly with ignition on, engine off
This is the reading a few seconds after switching key on, just the time to grab voltmeter and position the electrodes. This would be the time when ecm primes the pump or slightly after that as i am not fast enough after i switch the keys on to position the electrodes on the connector.

Crocodile clips?
Author:  Maz [ 22 Sep 2019 14:09 ]
Post subject:  Re: Xb12s 2005 fuel pump runs constantly with ignition on, engine off
Only wires you're interested in are gray and brown yellow.
Disconnect the fuel pump, on the harness side connect your meter across the above and switch the ignition on, you should see battery voltage for a few seconds (prime period) and then nothing.
If the meter shows battery voltage permanently, then the brown/yellow has gone to ground somewhere between the connector and the ECM or the ECM is faulty.
If it behaves as described above, then it's time to remove the swingarm and pump to repair the grounded brown/yellow......very common.
Author:  Buelladen [ 22 Sep 2019 18:54 ]
Post subject:  Re: Xb12s 2005 fuel pump runs constantly with ignition on, engine off
Thank you so much Maz,
To recap, doing the check you suggested,
My situation is (see picture attached showing readings from both sides of the connector for reference only- i obviously tested only the harness side)
-Grey wire permanent 13v (bottom right in the connector in the picture)
-Yellow/red wire12v permanently (fuel level wire i believe-bottom left in the picture)
-Brown/yellow wire (the one that should give the signal to the pump) has ZERO voltage THROUGHOUT, (top right in the picture) ie i put the ignition on and has NO voltage. Of note, i tested the continuity of the brown/yellow wire between the ecm (i umplugged it and stuck the voltmenter in its pin contact- it is on black connector and is N3 of top row) and the pump connector (harness side) and the wire is NOT interrupted, ie whatever the ECM sends through the brown/yellow wire it reaches the pumps connector, so why does it show ZERO volt?
The situation above is different from what you describe isn't it?
I am losing my mind over this.
By the way the bike starts and runs well, i did 20 laps around my block, ready to push it, but it goes fine.
Only issue is the pump is ALWAYS activated when i put the ignition on, even if engine is off.
Also worth remembering, none of the pins of the plug/socket (with the exception of black wire on harness side) are grounded. None of them blips when tested against the frame and the neg of the battery woth the voltmeter on Ohm mode. I should have a grounded wire if it was chaffed somewhere, either inside or outside the pump!
Thank you so much i am going crazy and you are being a lighthouse in the night!!

(To Jazzbutcher, i asked my son to turn key while i kept the voltmeter connectors in place, closest thing to a crocodile i found in the house!)
Cheers all

Attachments:
IMG_20190922_185259.jpg
IMG_20190922_185259.jpg [ 624.71 KiB | Viewed 1419 times ]
IMG_20190921_230500.jpg
IMG_20190921_230500.jpg [ 1.57 MiB | Viewed 1419 times ]
Author:  Maz [ 22 Sep 2019 19:35 ]
Post subject:  Re: Xb12s 2005 fuel pump runs constantly with ignition on, engine off
Brown/yellow will never show voltage as it's a switched earth.....gray wire is switched ignition feed and the ECM provides a switched ground via the brown/yellow, if you'd done the test as I said your meter represents the pump.
A grounded earth within the pump won't cause any issues other than if the bike is dropped the BAS won't kill the pump....so if you can't be bothered repairing it, leave well alone ! :)
Author:  Buelladen [ 22 Sep 2019 19:48 ]
Post subject:  Re: Xb12s 2005 fuel pump runs constantly with ignition on, engine off
So you think my situation re connector voltages is normal? Meaning on the harness side of things it is all working as it should?
Are you sure what i described proves that the grounded earth is INSIDE the pump?
I just wanted to rule out i had messed something around the ECM and wire loom and caused a ground on harness side.
If you feel that side of things is fine, and as a result my malfunction can only mean the grounded eart is inside the pump I am at least relieved it wasn't me causing the issue.
Maz, besides the above I would like to give you a call tomorrow re doing my oil pump gear and other stuff, can you add you phone/best time to call tomorrow.
I can't thank you enough for this diagnostic you have done for me and the time/expertise you spent on it. Can i at least make a paypal donation? unlike other people here you are a professional so you need to get paid for consultancy either at the shop or remotely
Cheers
Author:  Maz [ 22 Sep 2019 19:57 ]
Post subject:  Re: Xb12s 2005 fuel pump runs constantly with ignition on, engine off
YHPM

Diagnostics are always FOC :yup:
Page 1 of 1 All times are UTC
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/