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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: spextattoo on July 25, 2021, 10:04:29 PM
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Hello everyone,
My name is Peter,I have a 1985 K100 rs,I live in Austin Texas. Over the last months I have been working on the bike,doing maintenance and some mods to make the bike more to my liking. I took of all the plastic fairing cases etc.
Rebuild water/oil pump,spine lube,changed all the fluids.modified the blinker relay,rebuilt the brakes etc etc Cleaned and scrubbed and cleaned some more.So I got the bike going and drive it for the first time,it runs great,till I see the temp warning light come one after maybe a mile. Pull over and let it cool off for an hour and drive back home another mile or so. Temp light comes on,shut it off,let it cool again .
I got a new thermostat,coolant sensor, a used cooling relay,removed the vacuum sensor and plugged the barb on cyl 1 on the throttle body.
Installed all that,new coolant for Alu engines.
Now the bike turns over but won't start.I pull the fuel line to the fuel rail ,hit start,but no fuel squirting out the fuel line....
open the tank ,took the fuel hose that goes to the top of the pump off the filter,pushed start... at this time I should have fuel squirting out of the hose,correct? but nothing.It's a new pump,it worked before,has maybe 5 miles on it ,checked the fuse which seemed good,replaced it just to make sure.Even put the old cooling relay back in to make sure that is not the issue,but that shouldn't even have anything to do with the fuel pump,right? So I checked all the fuses and turns out I don't get any power to the fuel pump fuse (fuse6),but I have power to the 4 pin plug,how does that make any sense? I checked the back of the fuse panel and it all looks fine.
fuse1 12.88V
Fuse2 6.5
Fuse3 11.66
Fuse4 0V
Fuse5 0V
Fuse6 0V
Fuse7 7.5V
4pin plug to tank:
green/white-brown/black 10.98V
green/white-brown/white 10.97V
green/white-brown 10.87
green/white-2nd brown 0.0V
This is with ignition turned on ,battery is holding a charge 12,7 V
I thought I was gonna jump the pump (just for a second to see if it is running)
from right side of fuse 4 to left side fuse 6,but since I didn't have any power on the fuse locations,I didn't even try.
Put everything together after I pulled the fuel pump relay to inspect and clean contacts,pushed start 3-4 times and nothing,any advice is greatly appreciated,anyone savvy with this stuff? THANX A Bunch
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There should be only 1 solid brown wire, that is ground for the fuel pump and the fuel level float switches.
Brown/white and brown/black are for the fuel level dash indicators.
Green/white is the fuel pump power feed from the fuel injection relay--- thru fuse #6.
check your ground wire(solid brown-- no stripe) connection to the frame. Sounds like you have a weak/no ground connection. I believe that it terminates under the fuel tank.
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The four pin plug to the tank has these four wires:
Green/white - fuel pump 12V+ when the motor is turning
Brown - ground
White - fuel level sender to instrument cluster
Yellow - fuel level sender to optional fuel gauge
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There should be only 1 solid brown wire, that is ground for the fuel pump and the fuel level float switches.
Brown/white and brown/black are for the fuel level dash indicators.
Green/white is the fuel pump power feed from the fuel injection relay--- thru fuse #6.
check your ground wire(solid brown-- no stripe) connection to the frame. Sounds like you have a weak/no ground connection. I believe that it terminates under the fuel tank.
THX for the response,
I cur back the plastic tube to have a better look at the wires,and the colors are as follows:
green/white solid brown brown/white brown/black
the wire group makes it directly into the main harness under the tank and looks original and unmolested.
So if I check for continuity with the volt meter between the brown wire and the frame there should be no resistance?
I did mention that the bike had no issues until I started redoing the cooling system,right? I didn't touch the plug wires or the main harness.
I also attached a picture of the 4 pin plug and wires,thx again.
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THX for the response,
I cur back the plastic tube to have a better look at the wires,and the colors are as follows:
green/white solid brown brown/white brown/black
the wire group makes it directly into the main harness under the tank and looks original and unmolested.
So if I check for continuity with the volt meter between the brown wire and the frame there should be no resistance?
I did mention that the bike had no issues until I started redoing the cooling system,right? I didn't touch the plug wires or the main harness.
I also attached a picture of the 4 pin plug and wires,thx again.
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- you should use the continuity / resistance function on your multimeter and you should read 0 Ohms (or close to it) when testing between Brown and battery negative.
- you should use the DC Volt function on your multimeter and you should read 12 volts (or close to it) between Green/White and battery negative when you do the following: (1) turn on the ignition (2) set the kill switch in normal position (3) press the start button. The voltage should remain for 1.5 seconds AFTER you release the start button.
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Thx for the explanation,it's obvious I don't know how to use a meter,much appreciated !
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If you still have issues after testing ok. You still might want to get replace the 4 pin tank connector, a known trouble . I replaced mine with a 4 pin flat trailer connector, but there are other connectors.
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That is super hard to do on an early model K100 because the harness plugs directly into the fuel sender / pump connector and there is no pigtail on the tank to allow a substitution.
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That is super hard to do on an early model K100 because the harness plugs directly into the fuel sender / pump connector and there is no pigtail on the tank to allow a substitution.
ya learn something new every day! 112350
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On an 85, the white nylon alarm connector in the relay box is the same as the fuel tank connector so you can swap that in if the connector that goes to the fuel level sender is flaky.
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- you should use the continuity / resistance function on your multimeter and you should read 0 Ohms (or close to it) when testing between Brown and battery negative.
- you should use the DC Volt function on your multimeter and you should read 12 volts (or close to it) between Green/White and battery negative when you do the following: (1) turn on the ignition (2) set the kill switch in normal position (3) press the start button. The voltage should remain for 1.5 seconds AFTER you release the start button.
Hi RBM,
did the test and I do have 0 ohms on the brown ,but nothing on the green/white with ignition turned on,pressed start button,kill switch at normal.
What do you suggest I ought to test next? It dawned on me that I could have run up the green/white wire to see if I can find the break before the plug.(if that what it is) It.s dark now,will do that tomorrow,just hope I 'll find it before that line disappears in the main harness. Thx so much for talking me through this,really appreciate you doing this.
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On an 85, the white nylon alarm connector in the relay box is the same as the fuel tank connector so you can swap that in if the connector that goes to the fuel level sender is flaky.
I found one from the alarm system in the relay box,thx a bunch for responding
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If you still have issues after testing ok. You still might want to get replace the 4 pin tank connector, a known trouble . I replaced mine with a 4 pin flat trailer connector, but there are other connectors.
Gonna do that next,found a connector from the alarm system that doesn't exist,thx
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On an 85, the white nylon alarm connector in the relay box is the same as the fuel tank connector so you can swap that in if the connector that goes to the fuel level sender is flaky.
I found it and had it waiting ,thx a bunch for responding
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If you aren't getting +12vdc on the Green/white wire at the tank connector, next location to check is fuse#6.
The FI relay that supplies power has 2 switched contacts in it.
1 contact is the fuel pump circuit. Battery to relay to fuse #6 to fuel pump....
2nd contact is the +12vdc at the fuel injectors(green/red wire).
You can check the 2nd contact of the relay, use your volt meter on DC voltage and measure for +12vdc on the Green/red wire at the injectors. Measure the same as when checking the tank connector, and fuse #6... key on, kill switch on, starter button depressed.
One step at a time.
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If you aren't getting +12vdc on the Green/white wire at the tank connector, next location to check is fuse#6.
The FI relay that supplies power has 2 switched contacts in it.
1 contact is the fuel pump circuit. Battery to relay to fuse #6 to fuel pump....
2nd contact is the +12vdc at the fuel injectors(green/red wire).
You can check the 2nd contact of the relay, use your volt meter on DC voltage and measure for +12vdc on the Green/red wire at the injectors. Measure the same as when checking the tank connector, and fuse #6... key on, kill switch on, starter button depressed.
So to check the fuse: blk lead on battery neg,red lead on fuse 6. Ignition on? Starter pressed? What side of the fuse socket?
One step at a time.
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You might have to explain the relay test again...sorry ,THX
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You might have to explain the relay test again...sorry ,THX
As RBM spelled out in post #5 above, use the sequence to test both of the following. Red meter lead to each(one at a time), black meter lead to battery negative.
check for +12vdc at fuse#6 (both sides).
then check for +12vdc at the green/red wire at the injectors(only need to check one as they are all wired together).
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As RBM spelled out in post #5 above, use the sequence to test both of the following. Red meter lead to each(one at a time), black meter lead to battery negative.
check for +12vdc at fuse#6 (both sides).
then check for +12vdc at the green/red wire at the injectors(only need to check one as they are all wired together).
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As RBM spelled out in post #5 above, use the sequence to test both of the following. Red meter lead to each(one at a time), black meter lead to battery negative.
check for +12vdc at fuse#6 (both sides).
then check for +12vdc at the green/red wire at the injectors(only need to check one as they are all wired together).
Ignition on I assume,starter button pushed or not? Obvious and total green horn here...thx
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I thought I was gonna jump the pump (just for a second to see if it is running)
from right side of fuse 4 to left side fuse 6,but since I didn't have any power on the fuse locations,I didn't even try.
Did you end up trying to jump the pump out of the bike? You should try jumping the fuel pump externally directly from the battery to rule out 100% that the pump is not defective. There is a possibility that your pump is bad, which is probably unlikely given that it is new, but not impossible. (please don't jump the pump inside the tank). I recently had an unrelated issue with my bike regarding blown fuses and erratic fuel pump behavior, and after much troubleshooting, a new pump resolved my issue. I've linked the thread below if you'd like to reference it.
THREAD: http://www.motobrick.com/index.php?topic=14371.0
Best of luck,
Seb
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Did you end up trying to jump the pump out of the bike? You should try jumping the fuel pump externally directly from the battery to rule out 100% that the pump is not defective. There is a possibility that your pump is bad, which is probably unlikely given that it is new, but not impossible. (please don't jump the pump inside the tank). I recently had an unrelated issue with my bike regarding blown fuses and erratic fuel pump behavior, and after much troubleshooting, a new pump resolved my issue. I've linked the thread below if you'd like to reference it.
THREAD: http://www.motobrick.com/index.php?topic=14371.0
Best of luck,
Seb
Is there a way to jump the pump without taking it out of the tan? THX
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Ignition on I assume,starter button pushed or not? Obvious and total green horn here...thx
Test results fuse #6
ignition on ignition on
at fuse: right side 0.03 left side 0.03 starter pushed: right side 0.5 falls to 0.3 left side 0.5 falls to 0.3
at fuse box
no fuse right side: 0.03 left side 0.00
I jumped the pump from right side of fuse 4 to left side of fuse 6,I can hear the pump wizzing away.
PUMP WORKS ! good
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Seb
Is there a way to jump the pump without taking it out of the tan? THX
You most definitely can jump the pump inside the bike, but I wouldn't recommend it given that it is sitting in gasoline and any electrical spark is a risk of a fire. Removing the fuel pump is very easy, it is only held by two clips on each end of the pump. You firstly remove the gas cap. You hold in both clips, pull the pump up and out of the tank. You then remove the hose leading to the fuel filter, and both + and - wires.
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I jumped the pump from right side of fuse 4 to left side of fuse 6,I can hear the pump wizzing away.
PUMP WORKS ! good !
NVM, ignore my previous reply. If the pump whizzes on, then you can rule it out as a potential issue. This means that your issue is most likely wiring related based off the previous thread replies. I don't have the most knowledge related to the electronics/wiring of the K bikes, hopefully with the input of someone more knowledgeable you'll be able to get your K back on the road soon.
Seb
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THX SEB
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You want to do the tests suggested by Scott with the start button pressed.
When you press the button the contacts in the fuel relay should close, providing battery power from the red lead, to the green/red wires, one to the pump, the other to the injectors. While cranking you should also be able to hear the injectors clicking on and off.
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I don't think I can hear anything over the cranking noise...thx
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Test results fuse #6
< .... essentially no power ... >
Ok, so it's pointing to the FI relay.
- test for +12V on one of the Green/Red wires on one of the injectors or on Pin 9 of the ECU with (1) ignition on (2) kill switch normal position (3) start button pressed. If you don't get that, this could be the relay, or the socket. Pull the FI relay from the socket and while its out, clean the pins.
- On the FI relay socket, Test for +12V on Pin 30 (Red). It should be present whether or not the ignition is on or off, whether or not the kill switch is on or not, whether or not the start button is pressed. If its not +12V, you have a battery positive wire connection fault. Look at the sires connected to the battery positive.
- On the FI relay socket, check for +12V on pin 86 (Green/Yellow) when the (1) ignition is on and (2) kill switch is normal.
- Replace the relay in the socket. Insert it and remove it several times to wipe the contacts clean of potential corrosion. Test for voltage on fuse #6 with (1) FI relay installed (2) ignition on (3) kill switch normal (4) start button pressed. If you still get 0V, then FI relay is bad. Replace it.
- The very last possibility if its none of these is that the Hall sensors or the ICU are acting up.
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After messing with it today,the fuel pump started acting the way it should,I can hear it working a second after I let go of the starter button.
Beats me.... will do the above test tomorrow and let you know .Thx again for sticking with me, much appreciated RBM
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It's very easy to avoid blowing up the gas tank when you jump power to the fuel pump. Attach ring terminals and screw them onto the fuel pump terminals BEFORE giving them any power. You will not generate any sparks that way.
I had a guy come by my house once who was riding his bike around with jumped power to the fuel pump via two wires under the gas cap.
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sounds like an intermittent problem which points to bad connectivity, loose connections, corrosion and stuff like that. Just go through your electrical relay box and use Dexoit to clean and protect connectors. Reseat the connectors (like relay sockets and fuses, etc.) repeatedly to that the action of inserting and removing and reinserting the connector pins wipe away the corrosion.
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Gonna finally solder in the new plug tomorrow,had it with the uncertainty THX again Robert
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Gonna finally solder in the new plug tomorrow,had it with the uncertainty.
Please post a photo of the plug and the sender to which it connects, Spex.
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Its the 4pin plug that connects to the sender unit at the left front side of the tank.It was also in the beginning of the thread,but somehow not there anymore THX
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It's very easy to avoid blowing up the gas tank when you jump power to the fuel pump. Attach ring terminals and screw them onto the fuel pump terminals BEFORE giving them any power. You will not generate any sparks that way.
I had a guy come by my house once who was riding his bike around with jumped power to the fuel pump via two wires under the gas cap.
You can jump the fuel pump from outside the tank by bridging right side of fuse 4 to left side of fuse 6,no sparks no explosions,happy neighbors..and you're still alive...you can also empty the tank this way...
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Its the 4pin plug that connects to the sender unit at the left front side of the tank.It was also in the beginning of the thread,but somehow not there anymore THX
Show the plug assembly at the floor of the tank from which the wires emerge that connect to the plug in your photo above.
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Location of the 4pin plug at the sender unit at the left side of the tank,tilt your head to the left,don't know what happened here
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You can jump the fuel pump from outside the tank by bridging right side of fuse 4 to left side of fuse 6,no sparks no explosions,happy neighbors..and you're still alive...you can also empty the tank this way...
That does not work if the connection to the fuel level sender is flaky. The only way to be 100% sure that the fuel pump is getting power is to jump directly to it.
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Ok, so it's pointing to the FI relay.
- test for +12V on one of the Green/Red wires on one of the injectors or on Pin 9 of the ECU with (1) ignition on (2) kill switch normal position (3) start button pressed. If you don't get that, this could be the relay, or the socket. Pull the FI relay from the socket and while its out, clean the pins.
- On the FI relay socket, Test for +12V on Pin 30 (Red). It should be present whether or not the ignition is on or off, whether or not the kill switch is on or not, whether or not the start button is pressed. If its not +12V, you have a battery positive wire connection fault. Look at the sires connected to the battery positive.
Hi there RBN,
thanx again for all your help and patience,very much appreciated. Just a conclusive summary :
So I got her running,overheating problem solved,the fan kicks in eventually by the time the bike goes up to temp.
I had put a new temp sensor and thermostat in and removed the vacuum switch on the throttle body as well as plugging the barb on Cyl 1.
I didn't want to cut away insulation on the injector wires and didn't know how to test them otherwise,so I moved down the list of your suggestions.
The first thing I did was to check the electronic ignition and it seemed that the plug was not securely inserted.
The next thing was to replace the 4pin plug at the tank with the one from the alarm system.
Trying to figure out which one of the ocean of relays (attachment 3)was the FI relay you were talking about,I went to the manual and in the pic it shows 2 fuel pump relays ,as they call it. (see attachment 1)
So I measured the socket at pin 30 on relay5 ,ignition on,on my model there was no red wire,but a green/brown and I got 12.70 V.
( don't remember if that was with starter pressed )
Then measured pin 86 at the socket,ignition on and got 12.56 V.
(again,don't remember if I had the starter pressed or not,but I got voltage )
The measured on Fuse6 ,ignition on,starter pressed and received 12.56 V on both sides of the fuse.
I didn't check fuel pump relay2 (see image 1) cause there was no mentioning of the pin layout anywhere in
Bernd Vogel's EFI troubleshooting Manual (attachment2) so on I went,put evrything back together and wouldn't you know it it fired right up.
So my guess would be, that first of the Electronic Ignition plug was loose, and the second thing was the 4 pin plug to the pump/sender unit was faulty (attachment4)
Just wanted to clarify in detail, in the hopes of it helping some other mechanic master mind like me,to get their bike back in motion.
So thank you so much for running me through this in detail and helping me find the problems.Your patience is unmatched !!!
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Actually the labels for the drawing are wrong. It should read;
3 - fuel relay
4 - load shed relay
5 - horn relay
6 - temperature relay
7 - bulb monitoring unit
8 - starter relay
11 - flasher unit.
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This is the relay box diagram for an 85 K
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This is the relay box diagram for an 85 K
I have a RS not a K ,if that makes a difference.Took the pic straight out the Clymer Manual page336 ,don't know what to say or believe anymore...and the bike runs and works properly,That's what matters THX
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1985 K100 RS
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Well, don't believe Clymers. That diagram got the FI, Horn and Load shed relays wrong as well as labeled the BMU as the second FI relay :johnny
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Actually the labels for the drawing are wrong. It should read;
3 - fuel relay
4 - load shed relay
5 - horn relay
6 - temperature relay
7 - bulb monitoring unit
8 - starter relay
11 - flasher unit.
I only have 7 fuses,not 11
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Those numbers in the drawing relate mostly to relays.
The Clymer manual is good, but that is one of the mistakes in it. A simple test, the horn relay which Clymer calls the fuel relay, remove it, then the horn won't work but the pump will.
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You might be right and I might just try it out,THX
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I have a RS not a K ,if that makes a difference.Took the pic straight out the Clymer Manual page336 ,don't know what to say or believe anymore...and the bike runs and works properly,That's what matters THX
85 K refers to any K bike made in 1985. The diagram is relevant to your bike. I have the same motorcycle.
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Just realized that as well,duuh,sorry I spent to much time on forums,trying to decipher who knows and who doesn't,thx