BMW K bikes (Bricks)

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1Back to top Go down   K75 cranking but not starting. Empty K75 cranking but not starting. on Fri Jun 05, 2020 5:55 am

Kim Hunter

Kim Hunter
New member
New member
Newly acquired barn find now trying to bring back to life.
The story so far.
I found this bike in a wrecking yard. It was not destined for dismantling but was bought by Wrecker for repair and sale. Mechanics could not get it running. 
I bought as complete and not running.
It would start up using starting spray but not continue to run. It had been standing for a long time as the fuel in the tank smelt like stale turpentine.
I found fuel pump fuse blown and would blow on cranking. Fuel pump, filter and hoses changed. Tank cleaned out.
Still blowing fuses.
Took fuel level sensor and wiring out. Here I found the +ve wire had insulation broken away and the wire was stretched around the metal float body. replaced wire ok and fuses no longer blowing and pump operates when cranking.
But still no starting. The mechanics assured me it was running before they got it but as they worked on it and tried to get running the faults got progressively worse. (I can only take them on their word on this). 
They were starting up their fork lift and jump starting it using that because the battery was no good.
I was thinking this probably caused the injector controller to fail.

Now I have found another post here on this issue but his problem was solved by cleaning up connectors. I don't think that is my problem but I will check all connectors.

I also found a guide on how to test the various electronic bits so will work thru that as I can.

But I wanted to know if anyone else has had a failed injector controller and if this was the same symptoms. Can jump starting cause electronics to be damaged?
Am I on the right path?
Any other things to look at?

    

2Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Fri Jun 05, 2020 6:17 am

K75cster

K75cster
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I'd confirm you have squirt at the injectors before going to much further. I've no idea where my stuff is these days but I used a 9v batt form an smoke detector and a horn button to rig up power for the injector. Then a can of spray injector cleaner was used to restart the spray through each injector.

You've already replaced the pump and filter so that should all work well enough. 
A new Battery would be smart if you don't want to weld the starter relay trying to turn the thing over with a slow battery.
Between the Neg strap and the Gearbox connection a large switch would be a good investment. may also help to upgrade the Neg strap's size too.

Just ensuring the connectors are clean and corrosion free will help with ensuring the electrics are free to do their stuff.

Where about's in Paxton are you? I could duck over this weekend if needs be.
Keith


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt 1992 K1100LT a blue one

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

3Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Fri Jun 05, 2020 6:33 am

MartinW

MartinW
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Are the spark plugs wet or dry after trying to start?
Regards Martin.


__________________________________________________
K75s Hybrid
    

4Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Fri Jun 05, 2020 7:05 am

92KK 84WW Olaf

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would check and recheck the connections to the unit under the seat before going any further. A fault in that only shows up by making it look like some other component has failed when in fact it is good. Fastest way on that is a quick swap with a known good one so beer for some K75 owning buddy to come along and its a 5 minute job. Run both bikes and see what happens. One, both or none depending on the issue.


If both run then you know you are looking at possibly dodgy big plug connections that need cleaning up . 

If his bike runs on your FICU but yours does not run on his FICU then your FICU is good, your problem is elsewhere.


If neither run there is a problem in your FICU but also other problems like ICU under the head stock [another easy enough swap]......can happen if someone takes an arc welder to a K and not disconnecting BOTH terminals although the wise still remove FICU first.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 105,200 miles
1983 K100RS 0011171 Fricka 606 29,495 miles Damn K Pox Its a Bat outta Hell Now 36,188  miles
    

5Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Fri Jun 05, 2020 9:42 am

RicK G

RicK G
VIP
VIP
Check the ignition Hall effect sensors. On a K75 there are 2 and if either is bad it's a no start because the injection is triggered by the #1 sensor.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

6Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Fri Jun 05, 2020 10:04 am

Laitch

Laitch
Life time member
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@Kim Hunter wrote:The mechanics assured me it was running before they got it but as they worked on it and tried to get running the faults got progressively worse.
The progressively worse in this statement and fuel odor like turpentine indicate to me that it's likely the injectors might be clogged—as 75cster reckoned—because they continued to receive dirty fuel.



Last edited by Laitch on Mon Jun 08, 2020 8:27 am; edited 1 time in total


__________________________________________________
1995 K75 77,000 miles
K75 cranking but not starting. Usa-lo10
    

7Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Fri Jun 05, 2020 11:15 am

Point-Seven-five

Point-Seven-five
Life time member
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Laitch beat me to it, the old fuel and crap in the fuel system was worked down into the injectors by the wrecking yard mechanics.  Now they're all plugged up and need to be cleaned.  That's the first thing that needs to be done.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

8Back to top Go down   K75 cranking but not starting. Empty Cleaning injectors. on Sun Jun 07, 2020 6:36 am

Kim Hunter

Kim Hunter
New member
New member
Thanks Gents for the assistance. Do you take the injector out to pulse and use cleaner on them?
I made up an LED bit to see if Controller is working. I try that tomorrow.

    

9Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Sun Jun 07, 2020 8:35 am

Laitch

Laitch
Life time member
Life time member
@Kim Hunter wrote: Do you take the injector out to pulse and use cleaner on them?
To establish that the injectors are clogged, you could detach the fuel rail with the injectors on it, crank the engine and see how well they spray. Pay attention. More than one person has set fire to their moto by misdirecting the fuel spray. If the injectors need work, you could detach them from the rail then send them out for for professional cleaning if that's feasible, replace them or detach them from the rail then attempt to clean them individually yourself without destroying them or your workspace by using one of several methods—like these—that you can find in a search of this site.


__________________________________________________
1995 K75 77,000 miles
K75 cranking but not starting. Usa-lo10
    

10Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Sun Jun 07, 2020 10:01 pm

K75cster

K75cster
Life time member
Life time member
The link Laitch gave is a gooden, I took mine out and fuelled them from a carby cleaner aerosol can and a 9v batt. Simple way to clean the insides, the new O rings can be had at the local super cheap offices. Whole injector kits as well for when ya get it goin. I still haven't seen them since I did it ages ago, might have loaned them out. 9v batt and and El connector for the Batt form the electronics store near NRMA Cess. a horn button, I think it was called a push to actuate momentary switch or something like that. And alligator clips to join it all to the injector.
If needs be just use another spare pair of hands and press to operate. But don't leave it on, last thing ya want to do is cook the injector.


__________________________________________________
Keith - 1987 K75c with r100rt replica fairing and half of a 1984 K100rt 1992 K1100LT a blue one

The Clever are adept at extricating themselves from situations that the wise would have avoided from the outset - QUOTE from david Hillel in Out of the Earth.
    

11Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Sun Jun 07, 2020 10:45 pm

MartinW

MartinW
Life time member
Life time member
If you want to get serious an injector tester/pulsar can be had for around $30-40 and a graduated vessel is around $10-12 from the home brew shop. With those two you can check whether the flows are even.
Regards Martin.K75 cranking but not starting. 250_ml12
K75 cranking but not starting. Inject10


__________________________________________________
K75s Hybrid
    

12Back to top Go down   K75 cranking but not starting. Empty Probable scenario on Mon Jun 08, 2020 5:16 am

Kim Hunter

Kim Hunter
New member
New member
Hello again.

I am now thinking that the wrecking yard did not contribute to faults. I reckon that it was parked up by owner long time ago when it would not run. Remember, I found it to be blowing fuel pump fuses caused by faulty pump wiring in the fuel tank. It must have stood for very long time for fuel to go off like it has.

Today I spent some time testing and proving electronic components using the advice you guys here provided.

Firstly I thought I would prove spark using a strobe timing light. Well I connected it up and no flash. mmmm. It would start using starter spray. What have I done? have I caused more damage. What I did prove is that you do not get spark from the injector leads. Fancy that? Fool. worried me for half an hour. But eventually I did it right and got strobe flash from the plug leads.
Then using LED method I proved signal is getting to injectors.
Next I removed Injectors. Whew more stale turps smell. They well and truly blocked.

My cousin has a work shop at Anna Bay. He has an ultra sonic cleaning bath in his shop. I will take them to him to clean.

Good progress made thank you to those here offering assistance.

    

13Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Mon Jun 08, 2020 6:31 am

92KK 84WW Olaf

avatar
Life time member
Life time member
If you haven't already done it replace all the fuel lines including those inside the tank not just replacing pump and filter and make sure the inside of the tank is squeaky clean before refitting the injectors. That should give you a clean fuel system.


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 105,200 miles
1983 K100RS 0011171 Fricka 606 29,495 miles Damn K Pox Its a Bat outta Hell Now 36,188  miles
    

14Back to top Go down   K75 cranking but not starting. Empty Re: K75 cranking but not starting. on Mon Jun 08, 2020 11:49 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Good to hear you have found the problem and a course of action.

Olaf's advice to replace fuel lines is excellent.  I would add that it would be good to remove the fuel rail, drain the old fuel and soak it it for a couple days in distilled white vinegar to clean out the rust that has probably coated the inside of the rail.  After a good soak, do a thorough flush to remove any loose debris that may be left in there.  Then you can put a coat of high temperature engine paint on it.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

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