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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: SeanK75 on February 21, 2015, 10:12:40 AM
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Hey guys,
I think I have a wiring issue but here is what's happening
-Fan and fuel pump come on at when the ignition is on.
-Fan is always on.
-Horn fuse blows occasionally.
-Temperature light flickers once in a while.
I've checked all the relays but I'm guessing I have a short somewhere? I can't imagine my temp is high as my coolant is topped up and and my fan runs all the time. Has any body else had the symptoms? Any advice?
Any help would be greatly appreciated. It's a 1994 K75s with 95000km.
Thanks!
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greetings seank75...
welcome to motobrick.com...
the fuel pump should not run unless you are first on the start button...
first thing i would do is remove the horn from the circuit and see if the fan still runs from cold... cause... shorted horns have been known to cause fan whack... usually no fan cause they are on the same fuse...
proally stuck relay though... butts i would look at the fuse block first... some folks put a wire jumper in there to power the fan circuit for constant fan to help reduce thigh roast...
the wiring for that motobrick is here...
(http://www.motobrick.com/index.php/topic,4926.msg30829.html#msg30829)
j o
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Hey Johnny,
Thanks for the help. By remove the fan from the circuit, do you mean disconnect the wire connection on the horn or from the relay? Horn is obviously more accessible. I had it in the shop in the summer and we swapped all the relays out with another k75 and same problem so I think the relays are ok.
Thanks
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Check temp sender to see if has gone to ground.
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horn...
id also remove and reset each fuse on ata time... look for a jumper installed with unskilled hands...
j o
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Thanks for the advice guys. I'm on a trip right now so I'm limited to the tools I have on me. I tried disconnecting the horn and didn't help. Anything else I can check without major surgery? Is the temp sender easily accessible?
Thanks
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greetings...
somebody here knows for sure butts it aints me... so in the meantime i would disconnect the connector from the jetronic brain... make sure its all clean... reconnect and see what happens... lotts of whack can happen because of those connections...
what is your whereabouts right now...
j o
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About your fan and warning light, this can happen if the relay have insufficient ground connection.
Try to run a temporary wire between the relay ground connector and battery negative terminal.
About the blowing fuse it's most likely that you have a short in the wires to the horn(s) or the fan.
Unless it have been a lot of modification in your relay box....the fuse supplies horn, fan and flasher relay.
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Expanding on what Inge suggested, there is also the remote possibility that the short/fault that's blowing your fuse could be the fan motor itself. they can/do go bad. More often than not they seize up and stop turning, but I have seen some that the brush holders inside the motor melt/deform and are then capable of shorting out.
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Thanks for all the suggestions guys. The fan is running all the time. As soon as I turn the key, even before it starts. My bike broke down and now it won't start. Finding this wiring issue seems like finding a needle in a haystack, but I'm going to pull the tank off tomorrow and get out my multimeter. My clutch boot and fuel filter went on my last trip, I'm beginning to wonder if touring with a 20 year old bike is a good idea, even if it is a kbike! I've done some reading and it sounds like it could be the temperature sensor so I'm going to check that first and inspect and flush the cooling system while im at it. I'll let you know what I find.
Thanks again for responding, it's really nice have some help in these situations.
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The sensor is of a dual element type, one for fan relay...the other for the Jetronic to calculate the mix.
As a test you can check both values and compare them, they should be identical.
Measure the resistance between contact #10 and 13 at the injection ECU Connector.
Count from the rear end, also the empty slots.
Remove the relay and measure between 31 and E in the socket.
At 25oC you should measure around 2300 ohms.
Higher temp.....lower resistance, if the wires or the element is shorted to ground...the Jetronic thinks
the engine overheats and it's not allowed to start.
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So I removed the harness from the temperature sensor and the fan is still coming on regardless Does that mean I've eliminated the possibility of the temp sensor?
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So I removed the harness from the temperature sensor and the fan is still coming on regardless Does that mean I've eliminated the possibility of the temp sensor?
Most likely not the sensor then if the fan still comes on. The jetronic computer provides the 'ground' reference for the fan relay, so there has to be something telling the computer to turn on the fan, or more than likely, you have some funky (ie dirty) ground connections. Sounds like the next step may be to open, and clean any/all ground connections from the battery to the multiple frame connections. And as Johnny suggested clean the computer plug contacts- both sides.
On the odd chance, did a previous owner install a manual fan override switch?
While you had it unplugged, did you try and start it?
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So I pulled the computer out and inspected the pins and it looks fairly clean. I tried to measure resistance from pin 10 to 13 and no reading came up. I tried to measure resistance from 31 to E on the fan relay socket, NOT the relay itself and no reading came up. Electronics is Greek to me. I can do a spline lube and replace the clutch but I'm limited with electrical knowledge. If I'm testing the resistance of the sensor do I touch each of the terminals on the sensor itself with the red and black leads of the multimeter?
Thanks guys
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When you did test for resistance, was the sensor connector connected?
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Ok tell me if this means anything. I tested the continuity from the fan relay ground (31) and the fan harness and it beeps. When I try the temp sensor harness I get no beep. Could that mean there's a ground fault between the relay and the temp sensor?
Thoughts?
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Ok I plugged in the temp sensor and tried again. I got 3.72 between #10 and 13 on the cpu harness. And 0.7 between 31 and e on the relay.
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Then it's the sensor that is the problem as the measured value for the relay is to low.
But it could also be the contacts or wiring, try to measure between each of the contacts on the sensor
and ground (sensor housing is ground)....if you gets the same values you need a new sensor.
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Housing meaning the connector pipe that the sensor threads into? I get readings that jump around between 8.00 and 12.00 on both contacts.
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I tried putting the black lead directly to 31(ground) on the relay and the red to each of the temp sensor connectors and it gave me the same consistent reading of 3.6.
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Then it seems like the sensor is OK, and the problem is somewhere between the sensor and the relay socket.
I'm assuming that the engine is stone cold.
First check the that the sensor connector is clean and no corrosion, next to check is the connector between
the engine harness and the chassis harness (five pole, under the tank, left rear corner) and of course the
relay socket (but that usually isn't a problem).
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Yes its about 7 degrees celcius here, just over 40 degrees Fahrenheit. I'm getting a steady 3.6 now on both connectors when I ground it the the connector pipe that the sensor threads into. Engine won't start and gas tank is off.
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So its likely a ground fault between the sensor and the relay correct? If things were functioning normally I would get a consistent 3.6 reading between 31(ground) and E(temp sensor)?
What the best way to chase this down. Check all grounds and failing that unwrap and chase the wires from the sensor to the relay?
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The ground is OK, the connection between the sensor and the relay socket is the problem.
Check the connectors as earlier described (post 20), you can also try to measure at the
chassis/engine connector to if it is any difference from the 0.7/3.6.
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Is this the right one? Which socket do I test? And to the relay or sensor?
Thanks
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That's the one, measure at the violet/green wire in female connector (which goes to the sensor) an ground.
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Ok when I'm getting 3.5 there when my black lead is on 31 (ground) in the relay socket if thats where it's supposed to go.
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Then do the same at the male part, the connection should be open.
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I'm getting no reading from the male pin to 31 on the relay.
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What do you mean by the connection should be open? The sensor is plugged in, the engine/chassis and relay are not. Yhanks
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I'm getting no reading from the male pin to 31 on the relay.
Then it looks normal, reconnect the chassis/engine connector and measure again between 31 and E in
the relay socket.
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Ok it reads 3.5.
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Try also to measure between 15 and A2 at the relay.
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So I seems like the temp sensor is fine. But when I turn the ignition on the fan still comes on. Can I trace it from the fan? What else could be signaling the fan? A fault maybe? Something that won't allow my bike to start. Any ideas? Horn and fan fuse seem to blow, maybe the circuits are touching somewhere because when I remove the horn fuse the fan doesn't run with the ignition.
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1.5 between A2 and 15.
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1.5 between A2 and 15.
And you measure on the terminals at the relay?....with the relay disconnected.
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Yes on the relay socket, A2(fan motor ) to 15(fuse #7)
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Not in the relay socket, but the relay itself.
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No reading from A2 to 15 on the relay. Only from 31 to E on the relay, 3.5
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No reading from A2 to 15 on the relay.
This is normal, it was just to check that the contacts wasn't welded closed.
Only from 31 to E on the relay, 3.5
what a coincidence, same value as in the socket.
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I'm not sure what that means. Is 3.5 not normal for the relay?
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Also reading 3.9 from 31 to 9 on the relay.
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I'm not sure what that means. Is 3.5 not normal for the relay?
No idea, as I never have needed to measure this connection.
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Well I REALLY appreciate your time. Thanks for your help. I'm stumped so I guess the next step is taking it in to my mechanic, unless you have any other ideas.
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Have you tried what I suggested earlier in this thread....with a temporary wire between 31 in the socket
and the battery negative terminal?
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I'll try now, sorry I missed that. I need to have the relay off to put the wire in, so what do I do once the wire is run?
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Twist the copper strands and push it up from the bottom of the socket so it makes contact with the
connector inside the socket, the relay must be present.
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Just tried and still the fan is on.
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Then I haven't any further ideas.
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I should mention that the ecu is still disconnected. Not sure that matters as the fan still comes on at ignition.
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That shouldn't make any difference.
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Scott did have the idea that maybe a override switch could have been installed by a PO.
Does the fan run with the relay disconnected?
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It only runs with the relay on. I also think the fuel pump comes on at the same time. Before I start it.
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I also think the fuel pump comes on at the same time. Before I start it.
That also isn't normal, the fuel pump should start to run when the starter button is pressed.
Does the wiring under the tank looks modified?
The fuel pump is powered from the FI relay which is managed by the ignition ECU which grounds
the relay coil.
It happens that this function in the ignition ECU goes haywire, instead of buying a new ignition ECU
owners/backyard workshop permanently grounds the relay coil...and the pump runs as long the
ignition is switched on......then it's a safety function that doesn't work anymore.
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15 on the relay is getting constant power on ignition. The relay is supposed to do the switching but I'm getting power from A2 from the relay when it's plugged in so is the relay bad maybe? Any way to test?
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I tested it by pulling the fan lead out of the relay harness and sticking my power tester in its place with the ignition on. Seems like the fan is getting a signal directly from the relay.
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That you have power on 15 when the ignition is switched on is normal. But the relay shouldn't close the
contacts so you get power out on A2.
So far in the testing I would also say that the problem must be internal in the relay, but you did mention
earlier in the thread that you have tested with swapping with a known good one...and fan did still run :dunno
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I'm getting constant power, from the green and white wires going to my fuel pump, on ignition as well.
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Try to remove fuse #6, and check if you still have power in the connector.
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I also noticed this on the fuses. There's a loop connecting fuses 6 and 7 together which seems strange to me because one fuse is 7.5 and the other is 15. Is this normal? Seems to me this is why the 7.5 fuse keeps blowing. Also of note, when I remove the loop I get no power to fan or green fuel pump wire. Thoughts?
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That is non factory, and can explain some of the problems...........I must study the wiring diagrams.
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Finally! It really makes a lot of sense. I'm just worried that the previous owner did that to fix another problem. I didn't see that on the wiring diagram. I'll have to Put it all back together and see how it works. Any idea why that would prevent it from starting? Or what kind of damage having those two fuse circuit joined would do?
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That is the reason to your fuel pump does run as long the ignition is switched on, it could have been done
for the same reason as described in post #53.
The same circuit also supplies the the electronic parts in the fan relay with Power, which should only be
powered when the engine is running......but I guess the difference would only be that the fan now runs as
long the engine is running.
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Inge, as I haven't had my hands on a K75 I'm a little confused with this one. According to my schematics and by the terminals you all are discussing the fan controller is a 6pin relay with some internal electronics.(I've got no reference for the relay electronic internals other than the fan contacts).
If this is so, could the electronics within the relay be bad.
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As said in post #56 I would have guessed a problem internal in the relay, if it haven't earlier been
swapped with a known good one....and same problem.
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As said in post #56 I would have guessed a problem internal in the relay, if it haven't earlier been
swapped with a known good one....and same problem.
Ok that explains it, I missed that he swapped it with a known good one.
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A picture is being painted. I think you're on to something with the wire being a band aid fix. I'm going to put it back together and try with a different relay. I'd rather buy a new ecu or relay than spend 7 hours chasing a phantom short! Thanks again for your help guys I wouldn't be at this point without your help! I won't get to it for a while as I had to sacrifice a rad hose to remove it. I'll be waiting for parts and troubleshooting again in a week or two. I'll keep you guys posted.
Thanks again,
Sean
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Good Luck :2thumbup: .
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Any idea on price of a new ecu and/or relay?
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With the jumper removed and everything back in place, does it start?
Fuel pump running with the starter button?
Headlight drop out with the starter button?
I'm guessing something else is bad somewhere else they wouldn't have put that jumper in.
A relay will be much cheaper than an ECU, but I'm guessing that a bike breaker would be your most economical place to look. Not sure that an ECU would be available from BMW.
There is always flea-bay as well, equally as risky as a breaker in not getting a bad one.
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Didn't have time to put the radiator back together and put the fuel tank on. When I removed the jumper the fan power didn't go on with the ignition and green wire didn't show power to the fuel pump anymore so that should solve both of those mysteries. I'm hoping my local shop still has the other K75 kicking around so I can swap some parts out, relays, ecu etc. and see what the issue(s) are. I might try and go out there on Saturday next weekend. I'll let you guys know how it goes. Can't thank you guys enough for the help. I bought the bike a couple years ago and was constantly switching blown fuses and worrying about my bike on trips. I ride with 4 other friends and the last trip we did my clutch boot and fuel filter went at different times! It's nice to finally be close to having a solution on this, I feel like my bike will be finally be reliable soon and I wont have to be the guy who always breaks down anymore :clap:
Luckily I've always been able to fix it and make it home!
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Congrats! :riding: ..but as earlier mentioned, I would guess that the fan will run as long the engine is running.
It's also this jumper that have caused the blowing fuses so that is also history.
I would guess the jumper is placed there because of a nonfunctional FI relay, but this can be investigated
when it's possible to touch the starter button........BTW, is the FI relay present in the relay box?
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I'll take a look for the FI relay. It looked pretty packed in there, didn't notice anything missing. I'll let you know when I take a look. Good point about checking the starter switch. I wish I would have checked before I left. Bike is in a friend's garage. Any idea what the green and white wires are for going into the fuel tank? I think green Is for the pump but not sure about white.
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About the fuel tank connector, green is power to the fuel pump, white is signal for the low level warning lamp,
yellow is for the gauge (if fitted) and the brown is ground.
About the FI relay, in the front right corner of the relay box you have four relays if you have ABS brakes.
The front left of these four is the FI relay, if you don't have ABS the rear left socket is empty.
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With the tank and rad off I won't be able to start it, but I'd like to test the starter button to see if that green wire gets power when The starter is pushed. Is it safe to try that? Is there a safe way to try that as is?
Also, I think there's a small square black relay in the front left of the relay compartment. Do you have a diagram for the connectors?
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When looking back on the picture of the relay box it seems like you have a pre -94 model,
then what I did say about the relays in post #73 isn't valid.
And the FI relay must be present for the function even when the current comes in through the back door.
And then as you say the FI relay is in the front left corner, ....is the output marked 87/87 or 87/87b ?
About testing the relay you can just disconnect the signal connector at the starter relay so the engine don't
turn.....but on the other hand it could be that it need to be turning before the relay gets a signal.
If you try, just do some short pushes on the starter button....don't keep it pushed for longer periods.
About the relay connectors: 86 coil signal, 85 coil ground, 30 input contact, 87 output contact.
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I'll take a better pic of the relay box. I did remove a couple relays to wrestle the fuses out of the box so it may not look right in that picture. I tried the starter and the fuel pump is getting power on starter without the jumper. Jetonic cpu is still unplugged though. Not sure if that matters.
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A new picture isn't necessary, could see that the horn and LSR relay was of the older type.
If the fuel pump now gets power, I wonder why the PO have placed the jumper there in the first place.
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I'm not sure. Although I should mention that when I had it in the shop last summer my mechanic pulled one of the fuses (6 or 7 I can't recall) and the bike started up with no fan. We thought we had solved the problem for the time being as I was heading on a trip the next day. Half hour into the trip the bike cut out and I pulled over and popped the missing fuse back in and everything worked again. My guess would be that the fuel pump was getting intermittent power and that was the bandaid solution. Do you think it's a short or a computer related problem?
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I have no idea what the problem is, too few clues, only way to find out is to start measuring when the
problem is present.
But I would guess what I have suspected earlier that you have a intermittent ground connection at the
FI relay coil in the ignition ECU.
What you can do is to connect a temporary wire at the relay 85 terminal, the other end you just lay in
the tool tray under the seat (unless you have a low seat model).
Next time the bike stops you ground the wire, if it then starts.....you need a new/used ignition ECU.
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Do you have the last seven digits of your VIN number easily accessible, then we can find out how old it really is.
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Vin number is: WB1056207R0255367
I've emailed the PO to see if he know about it. He was the second owner so who knows.
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Then it's produced in May -94....so it is a -94.
You did write K75S in the first post, so I did guess that was correct...............
the layout on the electrics was changed on different times on different models.
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Text have been added to post #79.
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What exactly does that do?
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If the ground connection at the FI relay coil is lost the fuel pump stops and FI system shuts down.
This is also described in post #53....and I suspect that the jumper between fuse 6 & 7 was placed
there to mask the the intermittent ground connection at the relay coil.
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Ok I'll take a look on Wednesday when I'm working on it again. I'll keep you posted.
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So just to clarify, do you suspect it's the FI relay or the ecu? Or it will be one of those things if the fuel pump fails again and the ground wire from 85 works. Could the ground wire from 85 be a solution or would it send power to the fuel pump again with the ignition again?
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So I got the story from his mechanic when I called around with the Vin#. The bike had been sitting for a number of years and it wouldnt start so they tried to jumpstart the bike and they think it may have messed up the fuel computer. Jumping the fuses was a much cheaper alternative. I've replaced the relays just to be safe and I'll probably be looking for a new cpu. Does this add up to you? I don't want to use a wait and see approach and get left stranded on a trip. Is there any way to test an fuel cpu?
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It have been the ignition ECU (behind the headstock) which is the suspected part.
The jumper between fuse 6 & 7 have only masked the problem.
By using the temporary wire to ground the FI relay when the problem occurs, was to verify the real problem.
When you turn on the ignition the FI relay (which powers the fuel pump +++) coil gets gets power but it isn't
grounded.
When you push the starter button the ignition ECU gets a signal and grounds the FI relay coil and the fuel
pump starts.....and continue to run as long as the ignition ECU receives signal from the hall sensor that the
engine is turning.
Time to time the ignition ECU's goes haywire and this grounding function for the FI relay coil becoming intermittent.
By connecting the jumper between the fuses the fuel pump +++ still would receive power even when the
FI relay didn't function, but it would be to much load for the one fuse after some time.
By temporary grounding the relay coil when the problem occurs, you would verify that this is the problem.
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Ok! Put everything back together and tried to start it and still no luck. The fuel pump is getting power on startup. The fan runs only for a second or two after I let off the starter, but NOT while I'm trying to start it. I even tried hooking up 85 to ground and it worked as you said And The fan also comes on with it Hooked up like that, but the fan is on with the ignition Turned on, not after. So it must be getting fuel. what's next? Could it be the ignition system?
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Ok I pulled a plug and it was bone dry and getting spark. I disconnected the fan and tried to listen for the fuel pump. I can't say I heard it. I wonder if it's not working. It's been replaced about 10000k ago and I did the filter last summer. It looks clean and bike hasn't been sitting too long since it was replaced.
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If you just touch the starter button you should hear the fuel pump running ~1,5 sec after you have released the button.
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Does it matter if the fan is plugged in? I unplugged it to hear better. I also removed this full line to see if the if there was any fuel gking to the injectors and it was bone dry. No pressure, no fuel.
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The fan you don't need since the engine don't run anyway.
I would guess that the pump haven't been running, and if it does the next step would be to disconnect the filter.
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Yeah its getting power and I see my tester light on for about 1.5 seconds after I hit the button. Definitely not hearing the fuel pump. I have to laugh. It seems I am battling this war on two fronts. Tomorrow I'll take the tank assembly apart and see what's happening there. Looks like I could be in the market for an ECU AND a fuel pump. Talk about a tough week! :dunno
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Much gunk inside the tank? Is the prefilter under the pump OK? if the answer is yes and no, you can try to
reverse the pump for a short period ...10-15 sec.
Where did you measure for power to the pump?
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Tank is clean. Pre filter was changed within 5000 k, less than 6 months ago. I'm gking to pull it all apart and see if the lines or filter are plugged and if the pump spins. Also check the power to the pump inside the tank as well.
I'm testing the green wire at the harness before it goes into the tank.
Any reason to believe these two issues could be related? Would that fuse setup put any extra wear on the parts inside the tank? Like I said, the filter was clogged and replaced not less than 6 months ago.
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Easiest and most reliable metod I think would be to remove the pump and test it outside of the tank.
But if you run it dry, do it only for a few seconds to test..............
I don't think these issues is related.
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Ok I'll access the fuel tank issues tomorrow.
To put my mind at ease with the ECU, theres no way the Jetronic CPU directly interacts with the pump, correct? So it must be a faulty ECU? I will confirm by grounding 85 as you advised When/if the pump cuts out.
My mechanic says the ECU's rarely go bad, but he's seen a few Jetronic CPU's go bad. I just want to try and eliminate the possibility that it's the CPU.
Also, it sounded like the PO trying to jump start the bike caused some damage related to the fuel pump circuit which caused him to resort to jumping the fuse. So it's likely that it's the ECU that's messed up, not the Jet CPU. In your opinion does that sound about right?
Thanks Inge.
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Since you have confirmed that you have power in the wire to the pump, the next step is to find out why the
pump isn't running..........one step at the time.
About intermittent ground function in the ignition ECU (which isn't confirmed yet).....in another forum I'm a
member this particular error have happened to four different K's during the last three years.
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So some wierd things happening. Pulled the pump out and tested it Through the tank wiring and getting no response from the pump. I hooked up my power tester to be safe at the same time, pump definitely getting power. I was about to toss the pump in the parts bin but I decided to test it from the battery and sure enough it kicked over. Then I tried again through the tank wiring again and it worked. It felt like it had more kick from the battery it seemed to torque more in my hands. Could it be getting less power through the tank?
Maybe something was stuck and it worked it's way out. the filter seemed a little clogged. A little tough to blow through but not impossible. Picking up a replacement filter tomorrow to compare and test everything again.
Thoughts?
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What do those tank wires look like? Just worked an a friend's bike and the insulation on the wires to the pump was brittle and lots of it missing. Also wires partly oxidized.
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They don't look too bad at a glance. Tank was clean, but the pump pre filter was shot. It was open on both ends and falling apart.
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Pulled the pump out and tested it Through the tank wiring and getting no response from the pump. I was about to toss the pump in the parts bin but I decided to test it from the battery and sure enough it kicked over.
That's why I wanted you to test the pump outside of the tank, and what I did have in mind was to test it
directly from a battery... to rule out if the last part of the wiring was some part of the problem or not.
Yes, it happens that the terminals at the bottom of the tank goes bad...especially the ground side.
Maybe something was stuck and it worked it's way out. the filter seemed a little clogged.
That's why I earlier wanted you to try and reverse the pump for a short period, since you also earlier also
did have a clogged prefilter.....it could be that enough particles have find it's way into the pump to make a
problem (just guessing)........since the prefilter is clogged again it seems like a good idea to clean out the tank.
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but the pump pre filter was shot. It was open on both ends and falling apart.
Wasn't that a rather New filter? Could be a part of the problem, as it could be that you have got dirt into the pump.
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How can I test the tank wiring? Is it on on or off type of thing? Or can I inspect it visually? Everything looks really clean in the tank. Visually, the only amiss was the pump filter.
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The pump filter bag is what I meant. The fuel filter is new about 6 months ago, but seems a little restricted when I try to blow through it.
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First you need a new pre filter, but it could also be a idea to flush through the pump in both directions to be shure that its clean.
Have a look at this: http://www.motobrick.com/index.php/topic,5576.msg35083.html#msg35083 (http://www.motobrick.com/index.php/topic,5576.msg35083.html#msg35083)
About the terminals through the tank bottom, you can inspect them visually, both inside and under the tank.
If you find them suspected on the inside you need to remove the float mechanism from the tank,
you then would need a new o-ring.
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I had one of those pre-filters do the same thing. I was able to "repair" it with a sewing needle and thread and sealed it back up..... I considered the office stapler, but went the needle and thread route.
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They want 75$ just for that little filter bag! I might just get it to be safe. I can see the old one is deteriorating on both ends, it's the only thing that I think could be giving my pump and filter problems. The rest of the tank is clean as a whistle.
Inge, thanks for the link on the pump. I'll try that before I put everything back. It's a great idea. That way I can see how it functions and if it stutters at all.
By techron you just mean chevron gas with techron right?
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Sounds to me that its only Techron that have been....don't know what's inside the bottles since we ain't
got that product on this side of the pond.....but I would guess it's safer to work with than fuel.
Less chance to go into orbit, if...............
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They want 75$ just for that little filter bag!
Less than 10$ at Euromotorelectrics (http://www.euromotoelectrics.com/BMW-K-R-Fuel-Strainer-Sock-16-14-1-341-233-p/ff-233.htm), non genuine, but Bosch is a well known brand, even if it have half the lifetime you save a lot..........buy two....and eventually other service part you need.
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Had a chance to look at my bike again today. I believe I've narrowed it down to a ground fault between the fuel pump and harness outside of the tank. I pulled the pump out and bypassed the tank Guage assembly, not sure what this part is called, and the pump worked. Upon inspection of guage assembly I found no visible problems? you mentioned the ground fault was common, is there anyway to fix it? Or am I better off to just replace the part? 185$
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The ground connection is directly at the mounting plate...both inside and outside, so you should be able to
check it visually.
If necessery remove the unit from the tank....also check the wires between the unit (mounting plate)
and the connector, and the unit (mounting plate) and the fuel pump connectors have good connection.
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I've known of (1 specifically) that had the ground path break inside the sealed portion where the tank wires pass thru from the outside to the inside of the fuel tank. He had intermittent fuel pump failure.
The only way he was able to cure it was to replace the float assy. He was able to find a good used one for reasonable.
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The ground connection isn't going through the sealed portion, but directly on the mounting plate.
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I tested the wire from the mounting plate to the pump and it's good. I think the problem is inside the harness entering the mounting plate, which looks like a sealed unit. Seems like ill have to replace the float assembly.
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Where does the ground connect from outside the plate? All I can see is the wire gking into a white plastic connector directly through the plate. Also, the ground connection to the mounting Plate looks mildly corroded, but it looks like it's impossible to remove and clean it. Can't remember but I seem to remember is was riveted in place.
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On the underside of the unit it's a plastic housing which you can remove and check the ground connection.
And resolder the connection....or change out the part of the wire which is broken....
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I'll have another look at the assembly. Now that we've narrowed the issues to the jumped 6 and 7 fuse and the ground fault I'm the float assembly, would either of those things cause the temp light to flicker? It only starTed doing that recently before the bike eventually stopped starting due to the ground fault.
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The wires inside the tank are constantly immersed and the insulation hardens and cracks. The positive lead for the pump is strain-relieved with a tab to the fuel sender housing. The broken insulation can expose wires that can short to the housing. Remove the fuel level sender to inspect the unit. If it's just wires that look ratty, then replacing the wires is pretty straight forward and cheaper than a new unit.sender
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But replace with wire that can be submersed in fuel. Normal electrical wire insulation will deteriorate in fuel.
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Wire with Polyurethane insulation, not normal PVA insulation. Polyurethane is resistant to gas and oil.
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Now that we've narrowed the issues to the jumped 6 and 7 fuse and the ground fault I'm the float assembly, would either of those things cause the temp light to flicker?
Could be that the modded wiring have been causing it, as the power feed to the temp management relay PCB
is in the same circuit.....but can't say for shure....time will show.
But it might be a separate issue as well..........
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Turns out the ground fault was in the harness outside of the tank. Cut the wires, bypassed the harness and after a little coughing, she fired right up! Thanks for the help Inge, I found a good deal on a used ECU from an 87'. I'm going to swap it out for good measure, hopefully that will be it for a while! :2thumbup: