K75 Problems

[tkapelan]

I posted a few weeks ago that I couldn't get my K75 to start and that the choke and throttle cables had melted and the wiring to the coolant temp sensor were melted. Maybe you all remember...

So I have new cables on and spliced the wiring harness, removing the melted wires, with 18agw wires just like suggested. I expected the bike to start right up... No such luck. The bike will choke a long with the starter going but will not stay running and darker exhaust is coming out the tail pipe while this is happening. Could the bike just be flooded? What am I missing here? I went over the electrical system, it seems to be in tact, the bike wouldn't even fire if it was bad right?

In other words, I am at a loss. I just can't figure this thing out.

[35634]

Hope I'm not being too obvious, but have you pulled the plugs to see if they're wet?

[Brckridnbob]

Check for spark

:german

[BuddingGeezer]

Did you remove the air box when you made the repairs? If you did, did you make sure you reconnected the mass air flow sensor to its rubber boot properly?

Ralph Sims

[ghostridery2k]

check your ground cables for good conection. ......y2k

[tkapelan]

I stopped at the BMW dealer and picked up new plugs because I thought that maybe the old ones were wet. I put the new ones in, no dice. Still won't start. I checked the ground cables and are tight to the frame. I checked to make sure that there weren't any pinched wires under the tank. I'm desperate, I really have no idea whats going on. I think im in over my head.

[breyfogle]

** MELTED ** cables and wires !! If the bike got hot enough to melt stuff under the tank, there could be any number of less obvious things that might have been damaged. Good luck, I think you are going to need it !!

[deilenberger]

** MELTED ** cables and wires !! If the bike got hot enough to melt stuff under the tank, there could be any number of less obvious things that might have been damaged. Good luck, I think you are going to need it !!Absolutely agree. I seem to recall mentioning why the choke and throttle cables melted in a prior posting. Have you checked the ground going to the bars/throttle assembly?

If I had to guess - you're due for a new wiring harness. The current one probably has multiple melt-downs inside under the tape. BMW put a lot of wires through some very small spots on the K bikes (even more if you have ABS) - and it is not uncommon for the insulation to rub through internally in the harness causing shorts. Some bikes have gone up in flames due to this.. sounds like so far, you've been lucky.

I don't think you've found ALL the damage in the harness, which is why I'd suggest looking for a new/used wiring harness. Check some of the BMW recyclers who advertise in the owners news, and you might also put an ad in the fleamarket seeing if anyone has one.

I have BTDT on a K75S - and I finally just replaced the entire harness with a good used one.

EDIT: BTW - here is the original thread. I may merge these threads since they concern an ongoing problem by the same poster..
http://www.bmwmoa.org/forum/showthread.php?t=26624

[tkapelan]

Its funny that you mention installing a new wiring harness. When all this first happened, I started looking on ebay for parts. There just happened to be a wiring harness for auction which i eventually won. Lets hope that will work.

Do you think it would be worth while to replace the fuel pressure regulator and the, what I imagine is, vaccuum line that goes to the front of the throttle bodies that is wrap in the spring? Maybe the pressure regulator is crap and is just allowing too much fuel to the cylinders. The plugs keep getting wet when I try to start it.

[deilenberger]

Its funny that you mention installing a new wiring harness. When all this first happened, I started looking on ebay for parts. There just happened to be a wiring harness for auction which i eventually won. Lets hope that will work.

Do you think it would be worth while to replace the fuel pressure regulator and the, what I imagine is, vaccuum line that goes to the front of the throttle bodies that is wrap in the spring? Maybe the pressure regulator is crap and is just allowing too much fuel to the cylinders. The plugs keep getting wet when I try to start it.That's flailing - replacing parts without diagnostics. There are some simple tests to see if the FPR is working correctly - need a 0-50 PSI gauge, a T fitting and a bit of fuel line, and a few clamps.

The plugs will get wet if you have no ignition, or if the fuel injection is always on.. either of which could be caused by a melted down wiring harness.

Since you have the harness - as big a PITA as it is to put on - that's what I'd do first. Expect to get quite familiar with your bike while doing this. I'd suggest labeling each and every male/female connector - each half before disassembly.. then you can compare what goes where on the new one after you've disassembled things.

[tkapelan]

Finally got the bike running again. I had a friend come over and take a look for me. I think this guy is a BMW guru or something. I had the airbox and everything associated with it disconnected. He took a look at my wiring and said that it was "ok, but better if I would have soldered it" I used those crimp connectors since I don't have a soldering iron. Pressed the start button without the tank on the bike or mass air flow sensor hooked up. The damn thing started right up and stayed running. I was like shocked. I couldn't believe it. I put the whole bike back together and is running fine now.

We talked about it for a minute and decided that the mass air flow sensor wasn't connected properly and was calling for more and more fuel into the cylinders. This was just causing the bike to flood before it even had a chance to get started. :doh

So, in closing, thanks for all your tips on getting the bike running again! :bikes