MOTOBRICK.COM

TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: Flick on October 26, 2011, 07:27:08 PM

Title: k75 not starting
Post by: Flick on October 26, 2011, 07:27:08 PM

I had the water pump and starter relay go out on me on Saturday. Now after fixing that she wont start, the engine spins and i get flames out of the exhaust. I have spark on all three cylinders, I have fuel, and the intakes look clear. I just can't figure out what is wrong now. Does anyone have any idea what might be going on?

Title: Re: k75 not starting
Post by: johnny on October 26, 2011, 09:26:04 PM

any chance its flooded...

j o

Title: Re: k75 not starting
Post by: Flick on October 26, 2011, 10:08:15 PM

I pulled the plugs, they were a little wet. I will let them dry on the bench overnight and see if it gets better by the morning. It's always the simplest problems that leave you stumped.

Title: Re: k75 not starting
Post by: frankenduck on October 27, 2011, 12:15:14 AM

K75s are pretty easy to flood compared to some other engines.

Title: Re: k75 not starting
Post by: Roy S. on October 27, 2011, 02:02:59 AM

Quote from: frankenduck on October 27, 2011, 12:15:14 AM

K75s are pretty easy to flood compared to some other engines.

Ya-butt thay arrr smooooov ruuuuuunin 8)

Title: Re: k75 not starting
Post by: Flick on October 27, 2011, 11:01:32 AM

Quote from: johnny on October 26, 2011, 09:26:04 PM

any chance its flooded...

j o

I put the plugs back in this morning and its still not starting.

Title: Re: k75 not starting
Post by: kennybobby on October 27, 2011, 06:10:37 PM

What caused the starter relay to go bad--was the battery nearly dead and the contacts welded closed during cranking? 

If so did you replace the battery? 

If you did not replace the battery, what is your battery voltage with the key out of the ignition? 

If the battery is fully charged and the voltage is less than 12.8 just sitting there you need to replace the battery.  Fuel injection will not work with a weak battery.

Title: Re: k75 not starting
Post by: Flick on October 27, 2011, 06:22:56 PM

Quote from: kennybobby on October 27, 2011, 06:10:37 PM

What caused the starter relay to go bad--was the battery nearly dead and the contacts welded closed during cranking? 

If so did you replace the battery? 

If you did not replace the battery, what is your battery voltage with the key out of the ignition? 

If the battery is fully charged and the voltage is less than 12.8 just sitting there you need to replace the battery.  Fuel injection will not work with a weak battery.

The starter button stuck on. I have been using a car battery to test the bike. I just replaced the starter because it was burnt. the bike is spinning over much faster now but still nothing is happening.

Title: Re: k75 not starting
Post by: Chaos on October 27, 2011, 11:51:26 PM

Flames out the exhaust?   That ain't normal.  Valve or timing issue methinks.

Title: Re: k75 not starting
Post by: Flick on October 27, 2011, 11:57:45 PM

Quote from: Chaos on October 27, 2011, 11:51:26 PM

Flames out the exhaust?   That ain't normal.  Valve or timing issue methinks.

I just cant figure out how it would fall out of time while its setting

Title: Re: k75 not starting
Post by: Flick on October 28, 2011, 07:52:33 PM

So today's update.

Valve timing is good
Fuel injectors are good
all sensors are testing good
battery is good
coils are good
plugs are good

still not starting.

Unless someone in the Daytona Beach area is willing to let me use their K75 for a few minutes to check my ECUs I don't think i will ever figure out what is wrong.

Title: Re: k75 not starting
Post by: pallum on October 29, 2011, 03:54:39 AM

It's hard to diagnose such a strange problem, which is probably why I couldn't even think of the answer until now. I have had the same symptoms as you and fixed it with an ignition switch cleaning. Not sure how I haven't remembered this issue after all the trouble it caused me the first time, but it sounds just like what happened to me. At first it was intermittent, key on- crank but no start, key off, key on- crank but no start, key off, key on- starts right up.

Try hitting the brakes while you have the no start condition with the key still in the on position, if the dash lights dim (more than normal), the ignition switch is positively dirty.

If they don't dim, I'd clean out the switch anyways, easy insurance. ~30 minutes.
http://www.eilenberger.net/K75S/IgnitionSwitch/index.html (http://www.eilenberger.net/K75S/IgnitionSwitch/index.html)

Title: Re: k75 not starting
Post by: Flick on October 29, 2011, 03:03:29 PM

IT LIVES!!!!!!

I found a guy that had written a page on fixing the EFI system on a K100. http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start.htm (http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start.htm)

As it turns out my TPS was the problem. With the sensor unplugged I got the bike to fire with the starter spinning the engine the choke on full and the throttle cracked open. After some fiddling with the sensor, I hooked it back up. Now she is running! The only thing left to do is put all the bits I took off back on.

BMW K75 90% repaired (http://www.youtube.com/watch?v=pl-ua7DG4M4#ws)

Title: Re: k75 not starting
Post by: Chaos on October 29, 2011, 03:29:51 PM

Congrats!  At least you got the weather down there to enjoy it now  (50 and drizzly here :'( )

Title: Re: k75 not starting
Post by: johnny on October 29, 2011, 05:39:50 PM

tps... humm... plumb nertly... thans for the update...

j o