K75 - Not starting

[2K]

Hi, I'm new to forum. Some background, I have repurchased a K75RT ABS1 1993 bike that I previously owned back in 2009 (For those interested, then 30yo, now getting more K-bike friendly 38yo with young family). I sold it and moved to Australia where I also had a K75RT 1996 Ultima (with much missed electric screen and stereo). Anyway back in UK now, and saw on an auction site my old 2009 bike for sale as a non-runner. It looked exactly as I sold it. Pleased to say now parked back in my garage, but still a non-runner.

Some history on the bike, I sold it in 2009 with everything working fine with 70K on the clock. The guy who brought it from me removed the ABS, then sold it in 2010 to the guy I brought it off back in 2016. He had serviced it regularly but not ridden it much, and have all old MOT’s, now only covering 73K. The story goes he put it into a motorcycle repair garage in 2015 for its yearly MOT (UK health test) and a service (Oil change), of which I have both receipts. The same garage on completing work had a test ride and all fine, then went to start it again and it did not start. From what I understand it has sat in this motorcycle repair garage for almost a year with them ‘working on it’ between jobs and couldn’t get it to start.. they also put a dent in the tank, #&*@ sake, I digress.

The neutral light is on. However the horn and Headlight/Rear lights do not come on. Indicators and dash lights work. The only noise it makes when hitting the start button, kill switch in up position, is the lonely sound of return fuel being sprayed back in the tank, only. I’m sure it used to make a pump priming noise when switching on before. It doesn’t make typical starting noises in anyway when button pressed, only this return fuel sound.

I have to date; Replaced battery with OdessyPW680. Replaced all fuses. Replaced old fuel. Taken starter relay out and bench tested, it clicks! Taken starter motor out and cleaned not particularly sooty, not tested though. Cleaned Grounds under seat and on frame. Cleaned battery connectors both ends. Rocked it in 2nd and tried to bump start, no joy. I have a mutlimeter and good basic mechanical competency but not an electrical expert, Any suggestions to help get me and my old friend rolling again greatly appreciated. Thanks,

[The Mighty Gryphon]

You say you cleaned the starter.  Did you bench test it for operation?  Clamp it in a vise and put 12v on it to see if it turns. 

If not, that could be your problem.  If it does turn, you can start troubleshooting the starter circuit.  The first test there is to see if the starter relay clicks when you push the green button.

When the motor is turning over, we can get into fuel delivery and spark issues if there are any.

[2K]

The starter relay is not clicking when attached to the bike, but checking it with a meter, current is flowing freely through it whether the green button depressed or not.
Tested the starter motor last night off the bike on a bench.. on the floor actually. Those things can really move when you prod them with 12V! (thanks Gryphon, your suggestion reminded me of a flow diagram I saw somewhere, don't think my usual scatter gun approach is going to sort this one) Anyway, the starter motor turned fine, I only kept it turning for a few seconds but sounded good with revs building. So starter circuit it is next then!

[Laitch]

Gryphon, your suggestion reminded me of a flow diagram I saw somewhere,

It—along with most every kind of instruction you'd need except how to give yourself or others a vasectomy using tools found in the stock BMW kit—can be found using the Technical Library Card Catalog. Here it is, compliments of Bert Vogel via the K100 forum and the MB.C Technical Library. Now go help an elderly person cross the street.

If the starter is reinstalled, find the load shed relay and rap on it with a screwdriver handle then see if the bike starts.

[The Mighty Gryphon]

Get a cheap 12v buzzer and some alligator clip test leads from Radio Shack.  I like something that makes noise because I can concentrate on looking at what I am testing rather than my meter.

Start by connecting it to the hot wire to the starter, and work your way back if you don't hear anything there.  Let us know how you make out.

[2K]

An update.

The ignition module unit had failed, and required a replacement. It sits top centre under the tank, marked as BOSCH.

I swapped it for £39 used part, and bingo now have a response at starter button  - classic turning over noises now /  and all lights/indicators/horn working/turning all working as they should.

but still not starting.

I have taken all plugs out and cleaned (they were sooty black and wet), once cleaned checked for spark, but no spark on all three.

The next step was going to change the HT leads but with all three not working, think the problem is between ignition module unit and spark plugs.

[White Dog]

Please post your findings.  My K75 turns over now, but will not fire.  I've done the preliminary checks but don't know what else to do.

[Laitch]

I've done the preliminary checks . . .

Please be more specific. One man's preliminary could be another man's final.

Have you checked fuse 6, maybe substituting a new fuse there? Have you checked the right side 4-pin connector?

[White Dog]

Counting down from the top of the fuse panel, my #6 is listed as 7.5A Kraftstoffp.  Is that the one of which you speak?


I have spray cleaned the 4 pin plug from the tank sending unit to the front of the bike.  I made sure to snap it in place.  It is a bear to undo.

[Laitch]

my #6 is listed as 7.5A Kraftstoffp.  Is that the one of which you speak?

That's the one. Check it and put another fuse in there if you've got one. Have you checked anything else?

[White Dog]

Yes to both questions.  New fuse, double checked the fuel sender/pump 4 wire plug.  Tomorrow I will pull one of the spark plugs and see if I have a spark.  I have tried, unsuccessfully, to start with the clutch pulled in and kickstand up.  I'm sort of stumped until I can check for spark.

[The Mighty Gryphon]

White Dog, can you give a little more background?  Was the bike running previously?  Did this happen suddenly, or did things degrade to where it won't run at all?  Did you do any work on the bike just before the problem started?  How old is your fuel?  Did you clean out the tank?  Are the plugs wet after you try to start?  Has the bike been modified? 

There is a lot more we need to know to get a good picture of what you are dealing with.

[White Dog]

I was messing around with the 4 wire plug, trying to test the low fuel light.  I jumped sevaral wires and the white wire plug to the green/white plug and the low fuel light illuminated.  (Robmack over on the K100 forum wrote me that what I did was wrong, in that the white wire is a ground wire and I should not have put power to it.)  I do not have a fuel gauge on my model K75 so the yellow wire is not used.  I plugged the connector back together but the engine would not fire.  I pulled and tested all fuses with ohmmeter to be good.  I stated above I would test for spark.  I have spark.  Next, I tested for voltage on the green/white wire and ground but got no voltage with switch on.  I traced the green/white on my wiring diagram to the F1 relay.  My brake light works, which is also tied to the F1 relay.  This tells me I have a fuel issue, or a bad wire now.   I never blew a fuse.   I am open to other ideas and hopefully, a simple solution.

[The Mighty Gryphon]

So, to clarify for my addled brain, the engine ran before you started to do some tests on the tank wiring.  Is that correct? 

Have you been into other areas of the electrical system other than to troubleshoot the problem that occurred with the tank wiring?

The main problem as I understand it is that the fuel pump is not running.  Is that correct?

[White Dog]

So, to clarify for my addled brain, the engine ran before you started to do some tests on the tank wiring.  Is that correct?  Yes

Have you been into other areas of the electrical system other than to troubleshoot the problem that occurred with the tank wiring?  No, and I have checked all fuses.

The main problem as I understand it is that the fuel pump is not running.  Is that correct?  I'm not getting voltage to the fuel pump from the electrical circuit.

I also am not getting power to the F1 relay.  I tested with another relay that works in its spot but not in the F1 spot.  I can hear and feel the relays clicking but don't get that on F1 relay.

[White Dog]

Ok, Can you confirm that you have 12v on the green/red wire on the fuel injection relay?  Is this one of the wires that feeds the terminals under the F1 relay?  How do I get to that wire?

Can you confirm that you have 12v at the other end of that green/red wire where it connects to the fuse?  How do I get to that wire? Is the fuse panel removable?

Can you confirm that there is 12v on the other side of the fuse?   ???

Can you confirm that there is 12v at the end of the green/white wire at the fuel tank connector?  There is no power to that terminal.

These voltage readings should be taken with the negative wire from your tester connected to the ground connection above the shifter on the side of the intermediate housing.  With the engine not running, you will have to momentarily press the starter button to switch on the 12v to these circuits. My other relays click and the ABS pump does its thing when I switch on the ignition before pushing the start button..

Are you familiar with all the problems associated with the tank connector?  They are notorious for bad connections, primarily to the fuel pump.  I suspect this is where your problem is, but you need to do the checks outlined above to be sure.  Once I get power to the front side of the plug, then I can worry about the tightness of fit.  I did spray clean it already.  Did I mention I HATE electrical problems?

[The Mighty Gryphon]

Going back and reading your posts it appears the Fuel Injection relay is not being energized.  Can you feel it click when you press the start button? 

It looks like the relay is energized by the terminal with the violet/brown wire being grounded by the engine control unit.  If the relay is not being energized the problem may be in that unit.  If that is the problem, I'll have to defer to someone else who knows more about how it works.

[White Dog]

Going back and reading your posts it appears the Fuel Injection relay is not being energized.  Can you feel it click when you press the start button?  No, the relay does not click.  On my R1100RT when I switch on the ignition, I can hear the fuel pump working.  I would assume the K75 would do the same. 

It looks like the relay is energized by the terminal with the violet/brown wire being grounded by the engine control unit.  If the relay is not being energized the problem may be in that unit.  If that is the problem, I'll have to defer to someone else who knows more about how it works.

  YIKES!  That does not sound good.

[The Mighty Gryphon]

Not familiar with the R1100.  It may have a different control unit.  The K1100 models and the 4v K100 have Motronic controls that energize the fuel pump when the key is turned on.  The Jetronic doesn't energize the fuel pump until the start button is pushed.   

With the Jetronic system, the fuel injection relay is energized by the engine control unit.  The output is on pin 7 and goes through a yellow/brown wire.  The output on the pin is high and goes to ground when the starter button is pushed. 

If you pull the fuel injection relay and connect your meter across the socket terminals that have the yellow/brown and green/yellow wires on them do you see the meter read 12V when the start button is pushed?

If not, it may be a good idea to check the big connector on the engine control unit.  Shoot some contact cleaner in the connections and put it back together making sure it is tight.  Yours wouldn't be the first problem to be caused by that connector being loose or dirty.

[White Dog]

Not familiar with the R1100.  It may have a different control unit.  The K1100 models and the 4v K100 have Motronic controls that energize the fuel pump when the key is turned on.  The Jetronic doesn't energize the fuel pump until the start button is pushed.  Which does a '95 K75 have?

With the Jetronic system, the fuel injection relay is energized by the engine control unit.  The output is on pin 7 and goes through a yellow/brown wire.  The output on the pin is high and goes to ground when the starter button is pushed. 

If you pull the fuel injection relay and connect your meter across the socket terminals that have the yellow/brown and green/yellow wires on them do you see the meter read 12V when the start button is pushed?  Again, how do I access the wires?  I think they are on the underside of the box for the relays and that box is between the frame rails under the gas tank and above the engine.  Pulling gas tank is no problem, although mine is full of gas.  How much slack is there in the wiring to the relay box so that I could pull it up to see which wires you are talking about.  The F1 relay has 5 posts on it.

If not, it may be a good idea to check the big connector on the engine control unit.  Shoot some contact cleaner in the connections and put it back together making sure it is tight.  Yours wouldn't be the first problem to be caused by that connector being loose or dirty.  Is this the silver box which has a large cable bolted to the side and sits in the frame rails above the battery?   Sorry for the elementary questions, but I gotta learn sometime.

[Laitch]

1. Which does a '95 K75 have?
2. Again, how do I access the wires?
3. Is this the silver box which has a large cable bolted to the side and sits in the frame rails above the battery?

1. Jetronic
2. You'll pull the relay and access its wires' terminals in the box. Read this post and the posts following it.
3. It is the metal box under the tool box that is beneath the seat. A cable with an elongated plug is pushed into it and held in place by a spring latch. The plug has a hook on its left side. Once you've levered its latch, you pull outward from the right side of the plug near its cable. It will release and you can unhook it at the left. See the attached illustration from the 1994 K75 Rider's Manual.

How much voltage does your battery have right now?

[White Dog]

I just read 12.60V across the battery.  I charged the battery overnight but I've had the ignition on checking this and that today and probably pulled the voltage down a tenth or two.  Looks like it will be late Friday before I can get back to this project.  I know I don't have power going to the F1 relay.

Why will I need to pull the FI control unit box?  Can they be tested/repaired?

[Laitch]

Why will I need to pull the FI control unit box?

I think Gryph only suggested in Reply #18 that you disconnect the plug and clean its contacts, reconnect it then be certain it is secure.
Certain problems with them can be repaired; usually they are replaced.

[The Mighty Gryphon]

I am afraid that the original poster's lack of understanding of what he is dealing with(he admitted that he hated electrical problems) combined with a lack of knowledge about the bike will make troubleshooting via the forum an excruciating exercise in futility for all involved.  I fear the only outcome will be more electrical problems from the troubleshooting process.

My suggestion is that he take the bike to a competent mechanic who can troubleshoot the problem.  I suspect that it is something simple and shouldn't take too long to resolve.   

[White Dog]

I am afraid that the original poster's lack of understanding of what he is dealing with(he admitted that he hated electrical problems) combined with a lack of knowledge about the bike will make troubleshooting via the forum an excruciating exercise in futility for all involved.  I fear the only outcome will be more electrical problems from the troubleshooting process.

My suggestion is that he take the bike to a competent mechanic who can troubleshoot the problem.  I suspect that it is something simple and shouldn't take too long to resolve.

You may be confusing me with the original posting.  He hasn't posted since Feb. 13 wherein he identified his problem as electrical.  JUST IGNORE THE MESSAGES PRIOR TO MARCH 1.  My problem is related to the fuel side.  I may have admitted I hate electrical problems but am learning quickly with your sharing of knowledge.  I am pressed for time tonight and most of tomorrow, but tomorrow night and Sat. I would like to solve this problem.  I was given directions earlier on how to test the wiring going to the FI relay but I didn't see what to do if there is no power on the wires.  Can you further guide me?  I have tested power on relay terminal #30.  There is no power to this terminal.  Could a faulty side stand switch be cutting the power to the FI relay?