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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Adrianinottawa on August 15, 2017, 10:17:27 AM

Title: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 10:17:27 AM
Hey all, I have downloaded Crazy Frogs guide to trouble shooting the k75 and am going to use it to start trying to figure out whats wrong with my bike but thought I would post here as well to see if others had suggestions.  I was on a 4 day ride around the Georgian bay and was on the Manatoulin Island.  Rode back to the motel after dinner and turned the bike off.  Realized I was parked in the wrong spot and went to start the bike and it wouldnt start back up.  Starter starts and engine turns over but wont start.  Pushed it in the spot and left it for the night.  In the morning same result.  I pulled the plug and verified that I had spark.  Plug was dry.  Sounds like the fuel pump is running as well when I try to start it.  The bike was poorly serviced by previous owner, discovered this lately with a lot of little things(plug connections removed and wires twisted together then wrapped with electrical tape, starter bolts loose).  In my investigation in the parking lot I found the battery neutral bolt is stripped and barely maintains contact with the battery.  Any thoughts would be appreciated.  I am a refrigeration mechanic with a lot of tools that will make this diagnosis possible only thing missing is my manometer is meant for gas so doesnt read high enough for fuel pressure.

Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 10:24:04 AM
this is the guide i am going to work from http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start.htm.

Title: Re: 1987 k75 wont start
Post by: johnny on August 15, 2017, 10:37:30 AM
greetings...

top 4 causes for k75 no start are here...

http://www.motobrick.com/index.php/board,9.0.html

what is the voltage at the battery... if the alternator was not charging the battery due to lose battery wior... your battery could turn it over butts just whack enough not to fior it...

if you wanna know if its pumping fuel you can take the hose off the outlet of the fuel filter and hit the start button...

j o
Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 10:43:55 AM
Awesome thanks I will try it all shortly.  Nothing hurts quite like a 500mile uhaul bill.  Waiting for friend to show up to give me a hand getting it out of the truck.
Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 10:50:05 AM
Awesome thanks I will try it all shortly.  Nothing hurts quite like a 500mile uhaul bill.  Waiting for friend to show up to give me a hand getting it out of the truck.
Hey just saw the question now lol was too excited following the link you posted.  I honestly havent tested anything yet.  Waiting for help to get it out of the back of the Uhaul.  I dont think this is a battery issue as I kept working on it and trying to get it started for another hour and battery still had charge.  I dont want to open it up while its in the uhaul but will post my findings as soon as I get on it.
Title: Re: 1987 k75 wont start
Post by: ^Adrninistrator on August 15, 2017, 11:20:28 AM
Adrianinottawa:

I am Acute Toxicity, the Agent In Charge at the DMJ (Department Of Motobrick.com Justice).

The BMI (Bureau Of Motobrick.com Investigations) has confirmed that you violated motobrick.com protocol by not exhausting the search options available at motobrick.com.

This is your notification that another occurrence will trigger sanctions.

The protocol is located here for your review and compliance as defiance is futile. (http://www.motobrick.com/index.php/topic,3995.0.html)

A T
Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 11:37:16 AM
Adrianinottawa:

I am Acute Toxicity, the Agent In Charge at the DMJ (Department Of Motobrick.com Justice).

The BMI (Bureau Of Motobrick.com Investigations) has confirmed that you violated motobrick.com protocol by not exhausting the search options available at motobrick.com.

This is your notification that another occurrence will trigger sanctions.

The protocol is located here for your review and compliance as defiance is futile. (http://www.motobrick.com/index.php/topic,3995.0.html)

A T


Figured the fact I posted link that I found after an hour searching would show I had been using search and was simply asking for further input based on the guide I had found.  Go ahead and block me I will take my love for the brick elsewhere.
Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 11:49:29 AM
my apologies I am getting pissed off and tired should have rested after the 8 hour drive in a cube van

Title: Re: 1987 k75 wont start
Post by: johnny on August 15, 2017, 11:56:54 AM
greetings...

why do canadicans need refrigeration mechanics... to maintain the perfect curling sheet...

j o
Title: Re: 1987 k75 wont start
Post by: The Mighty Gryphon on August 15, 2017, 12:22:00 PM
How many miles on your brick? 

Was it in storage for a long time before you purchased it?

What does the inside of the fuel tank look like? 

There is a 4 pin connector with several yellow wires behind the right side battery cover that may or may not be labelled "Tank".  This is the power to your fuel pump and low fuel idiot lights.  That connector is responsible for a lot of the whack like you are seeing.

I would check it first.
Title: Re: 1987 k75 wont start
Post by: BrickMW on August 15, 2017, 12:27:52 PM
In my investigation in the parking lot I found the battery neutral bolt is stripped and barely maintains contact with the battery.


This should be addressed first, IMHO..


Loose / dirty / faulty ground connections cause many problems and crazy whack...
Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 01:10:42 PM
greetings...

why do canadicans need refrigeration mechanics... to maintain the perfect curling sheet...

j o


lol we don't get Florida hot but the igloos do melt in the summer.

Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 01:13:06 PM
How many miles on your brick? 

Was it in storage for a long time before you purchased it?

What does the inside of the fuel tank look like? 

There is a 4 pin connector with several yellow wires behind the right side battery cover that may or may not be labelled "Tank".  This is the power to your fuel pump and low fuel idiot lights.  That connector is responsible for a lot of the whack like you are seeing.

I would check it first.


I dont think it was in storage other than for the winter.  Inside of the fuel tank is very clean.  I replaced the fuel filter and intake when I got it due to power problems which made a vast improvement. 
Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 15, 2017, 01:27:18 PM
Not getting any voltage when measuring at the injectors while hitting the start button.  I am measuring in DC volts.  Wasnt sure whether this would be mV or just standard DC volts so tried both.  DC mV I got 37mV.  I am guessing this means nothing since it seems to me from what I have read on here that its just standard 12V DC to the injectors.  11.8 Volts at the battery.  I just had my little girl come home sick from school.  So much for getting my brick going on my day off.  Sorry for all the posts but as a Canuck we have very limited riding season which has been screwed over this year by record setting days of rain.  Gotta get this little lady up and running to enjoy whats left of the summer.  I will take a break on it till the weekend.
Title: Re: 1987 k75 wont start
Post by: alabrew on August 15, 2017, 02:04:48 PM
I'm going to be "that guy" who posts when they have no experience with that model, but I know that what I have a bad habit of doing is trying to start my '91 with the kickstand deployed, which will turn over the engine but it will not fire. It takes a few attempts before it occurs to me what is happening, only bike i have with that "feature". I'm not willing to disconnect it as it is there for my stupidity. Had a similar issue on the Yamaha Vision, stopped for gas, when I went to restart, it wouldn't, and I found the side stand safety switch was gummed up with grease and dirt.
Title: Re: 1987 k75 wont start
Post by: The Mighty Gryphon on August 15, 2017, 02:10:06 PM
'87 K75 does not have the sidestand interlock.  On the K75 the clutch retracts the sidestand so you can't ride off with it in the down position.
Title: Re: 1987 k75 wont start
Post by: BrickMW on August 15, 2017, 04:14:01 PM
I will take a break on it till the weekend.


...meanwhile, put the battery on a charger. 11.8V is low.


Perhaps try setting your meter for min/max to see the actual voltage that is being applied for milliseconds, not long enough for your meter to catch up. A better test would be to pull the injectors and rail, angle them into a suitable container, and watch for a 3-way hose down when you hit start.


Hope your little girl and your riding season improve soon.. :getwell:
Title: Re: 1987 k75 wont start
Post by: BlitzenGruv on August 16, 2017, 06:40:47 AM
[quote author=Adrianinottawa   I replaced the fuel filter and intake when I got it due to power problems which made a vast improvement.

If you used a BMW filter you're good to go. However, if you used an auto-store store replacement and the short bit of fuel line which came attached to the filter beware. That line is not rated for use inside the fuel tank. Fuel line which is not rated for submersion will swell and loosen from the fittings in the tank. Any fuel line inside the tank must be rated SAE J30R10.
That short bit of fuel line costs more than the filter.
Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on August 21, 2017, 02:34:51 PM
Got off work early and finally had a chance to sit down and look at the bike.  Started first try.... sigh I guess I will clean all the contacts pull apart and clean any electrical switches I can.  Will replace the neutral terminal on the battery.  In the hvac industry this is one of the most frustrating things and it happens often.  Customer calls got no cooling/heating whatever.  Get there and the sucker is running... :dunno2:
Title: Re: 1987 k75 wont start
Post by: The Mighty Gryphon on August 31, 2017, 08:31:09 AM
Good to hear you got it started.  You might want to go through the ECU connector and as many engine harness connectors as possible with some DeOxit ASAP.  That should go a long way toward improving the reliability factor. 

Hope you keep us posted on how you are doing with your bike.
Title: Re: 1987 k75 wont start
Post by: CNRED on August 31, 2017, 06:09:30 PM
This sounds like the problem I was chasing a few months ago.  Bike ran great for about 50 miles then would quit, not to start again until the next morning.  I cleaned every electrical conector I could find on the bike, replaced the fuel pump, pump dampher, fuel filter and hoses inside the tank with the appropriate BMW hoses, still the problem persisted.
It was the fuel sender.  When the bike would warm up, the wires from the four pin connector going to the fuel sender would lose condinunity and cut off power to the fuel pump.  Replaced the fuel sender with a new one, bike runs perfectly for the last 300 miles.
The next time it quits, push the starter button and let go, listen for the fuel pump to run for about 1 ½ seconds after you let go of the button.  If it does not, the pump is not getting power.
I found my problen with the help of members of this forum, be patient, take their suggestions, these are great bikes but a little quirky at times.
Title: Re: 1987 k75 wont start
Post by: Adrianinottawa on September 01, 2017, 10:52:51 PM
yeah that was one of my first thoughts was to listen for the fuel pump.  It would run for a second or so after trying to start it.  Had pressure in the lines to the injectors.  Its going to be a weird one just trying to get my hands on decent contact cleaner this weekend so I can work on it.  Not much riding weather left it feels like up here.  We are going down to just above freezing already overnight :(
Title: Re: 1987 k75 wont start
Post by: BrickMW on September 02, 2017, 08:43:03 AM
yeah that was one of my first thoughts was to listen for the fuel pump.  It would run for a second or so after trying to start it.  Had pressure in the lines to the injectors.  Its going to be a weird one just trying to get my hands on decent contact cleaner this weekend so I can work on it.  Not much riding weather left it feels like up here.  We are going down to just above freezing already overnight :(
Check with Steve's Music Store.. Their website indicates they carry Deoxit.

https://www.stevesmusic.com/

Sent from my SM-G935V using Tapatalk

Title: Re: 1987 k75 wont start
Post by: stokester on September 02, 2017, 09:12:21 AM
<snip> Its going to be a weird one just trying to get my hands on decent contact cleaner this weekend so I can work on it.  Not much riding weather left it feels like up here.  We are going down to just above freezing already overnight :(


Amazon has a full assortment of DeoxIT.
Title: Re: 1987 k75 wont start
Post by: johnny on September 02, 2017, 09:24:57 AM
greetings...

order online shipped free to your whole foods and delivered by drone...

or...

i getts my deoxit at the guitar center... butts they proally aints gotts them in ottotwa...

http://www.guitarcenter.com

j o
Title: Re: 1987 k75 wont start
Post by: BrickMW on September 02, 2017, 09:29:17 AM

Amazon has a full assortment of DeoxIT.
At the cost of a few more precious riding days waiting for the brown truck...

Plus it gives you that "warm fuzzy" to support your local economy.

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