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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: ExpatAussieBrick on June 27, 2019, 05:29:47 PM
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Hey guys,
So i'm a bit bloody stumped on what is happening with my bike. It's a 92 K75S and it's been running poorly the past few weeks after I had it serviced at BMW of Manhattan. It was running great after the service until about 30min after I left the dealership it suddenly refused to rev above 3000rpm and the engine slowly bogged down and died, almost causing me to be squashed like a bug by heavy traffic on the Queensborough bridge.
After I managed to coast down the bridge and get it started again it ran fine for a little while then back to stalling again. I decided it might be water in the tank or a bad fuel filter I drained the tank and replaced the fuel filter still nothing changed. I checked the plugs and they looked a little rich.
So I took it back to the dealership and they diagnosed it as running rich under load with a vacuum leak at the air intake manifold and the injectors. They replaced the rubber hoses under there and the Injector O rings but was still running roughly. They then installed a used Mass Air Flow Sensor thinking that would fix the problem it didn't. Frustrated I took it back from them not wanting to burn anymore cash.
They suggested that I try installing a new Hall Effects Sensor.
Does anyone have any other ideas about what it could be? I'm thinking of pulling the injectors myself and having a look at the spray pattern and also try a new HES. But I don't really wanna just keep throwing parts at it and hoping for the best without a clear diagnosis.
It's a shame it's my first BMW and it was a fantastic bike when it was running well only had it for 6 months. I'm from Australia but living in NYC and the bike is my only set of wheels to get me out of town this summer so I really wanna try getting it running again.
:beatdeadhorse:
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Sorry to hear your brick is turning into a wonkasaurus. Pics of the plugs will help. Has the fuel lines been replaced, the fuel pressure regulator? Sometimes the fuel lines get crimped under the tank and cause intermittent starvation, then the bike runs fine again, then acts up again. Have patience, and others will chime in that know waaaaay more then I.
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greetings...
poast up some photos... wanna see if its been bastardized...
im calling fore pin... do all this and ping back here...
http://www.motobrick.com/index.php/topic,11033.0.html
j o
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BMW service centers have all the diagnostic tools that anyone could want. The elements of efficient and predictable operation are the same in these motos as any other—fuel, air and spark. Staff trained in electronic diagnosis should be able to identify the problem, not guess at it. Throwing parts into a malfunctioning moto is what greenhorns do. You did right by getting away from them and not continuing to throw parts at it yourself.
What is the service they performed on the moto exactly? It seems as though it was running alright before you went there. Is that correct? If it is, I don't believe it's coincidental that the moto started running unpredictably after they handled it.
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Sounds like another example of current shop staff not having any training or experience with 25+ year old bike. If a computer can't tell them what's wrong, they don't know how to figure it out. Unfortunately most everything is going this direction.
They may be able to say that there are 'parts available for all bikes new and old'..... to bad they can't fix old bikes.
I'll get down off my soap box now... rant off.
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As per Nat the fuel return line between the FPR and the tank can crimp over, this will cause the bike to run rich and rough. The OEM return line has the bends molded in whereas a replacement straight piece of fuel line doesn't . If fitted with a straight piece of line crimping can occur especially on some of the cheaper hose that is around. The crimp can be hard to detect as when you slide the tank back it will sometimes uncrimp, feel and bend the last couple of inches of the line to see if it has delaminated or gone soft. High temperature days make the line more prone to crimping. If it has crimped either replace the line with an OEM line or fit a Unicoil over the last piece of line. Fitting an extra hose clamp below the Unicoil will prevent it from sliding down.
Regards Martin.
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You mentioned that you drained the tank and replaced the fuel filter, did you pull the fuel pump and look for accumulated sediment and crud clogging up the fuel strainer on the fuel pump? This would starve the fuel pump and thus the engine. After letting it sit a while, the sediment will drop off the strainer and then it would seem to work just fine until the sediment would get stirred up and clog the system again. This cycle runs in a tighter loop with less fuel in the tank.
I had a similar experience to yours on two motobricks. Removing and throughly cleaning the tank solved the issue completely. On one machine I had to replace the fuel strainer.
I agree with the others in that dealerships and other generalists aren't going to know much about these bikes. The bikes are too old and they have other fish to fry. They will just through new parts at the machine until the problem is solved.
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Welcome, and condolences on your situation. You definitely made the right decision to get away from the dealer. Any mechanic who equates an intake air leak with rich running should be avoided.
As was mentioned above, a picture of the spark plugs would be very handy. That will tell conclusively whether the bike is running rich or lean. There are several things I would have you check, but won't make any suggestions until I see what the plugs look like because the troubleshooting paths are different.
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Given it ran good until it warmed up and appears to be running rich, perhaps there is a sensor that thinks the bike is cold, calling for a rich, cold condition mixture that is unnecessary. Just thinking out loud, but seems like a logical area to explore. Hard to believe a BMW service facility can't figure it out. Good hunting.
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Thanks for all the suggestions guys! Great community never had this support on the previous two bikes I owned.
I am going to go through those basic 4 pin connectors and clean them up this sunday and post back.
In regards to the tank I've given it a good wipe down its very clean in there no sediment I can see all the rubber hoses in the tank are in good condition as far as I can tell. But no harm pulling the pump out to check I guess. Will check hoses to the FPR as well I am getting decent flow return to the tank when the engine is on but not sure if that means anything. The pump does have quite a loud hiss but that could be normal. The dealer told me the pump was fine they said it either fails and leaves you stranded or doesn't it's not intermittent they said they checked fuel pressure and it was in spec.
Now in terms of what had been has been done to the bike at the dealer they replaced the front and rear break pads they blead and refilled the break fluid they mounted two new lasertec tyres. They changed the engine oil and replaced the filter and they changed the oil in the final drive and transmission. As part of an all inclusive deal they were doing on annual service.
After all that the bike started running rough shortly after I took it back.
I bought this bike for very little $1500 on Craigslist its not been taken the best care of by the PO but it was at least garaged and came with a new battery. It didn't come with a service history so I took a risk but I thought it was still a lot of bike for that money even if I did have to replace a bunch of things.
Anyway will have a go working on it on Sunday and report back with photos.
Cheers
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Please take the bike out and run it until it starts to misbehave, bring it home and take photos of the spark plugs. The mixture is off, but without a plug reading there is no way to tell for sure whether it's rich or lean. Depending on which way it's off, it will guide the troubleshooting sequence. My money is on the engine temperature sensor, but without a plug reading I'm holding off on saying what I think it is.
It's good to learn how to do your own work on the bike. Except for the tires you could have done the rest of the work the dealer did with a few dollars in tools and maybe $100 for parts and supplies. The really good news is that the inmates here can talk you through almost any job on your bike.
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Hi Guys,
Update on the bike. So this afternoon I cleaned up the battery contacts and the 4 pin connector underneath the tank with deoxit and an old toothbrush. Also noticed that the big hose containing the wiring for the ECU fuel injection computer was pretty kinked around so straightened it out as best I could.
Here are some pics of the 4 pin.
4 pin male
https://www.dropbox.com/home/Bike%204%20PIN?preview=IMG_4051.JPG (https://www.dropbox.com/home/Bike%204%20PIN?preview=IMG_4051.JPG)
4 pin female
https://www.dropbox.com/home/Bike%204%20PIN?preview=IMG_4052.JPG (https://www.dropbox.com/home/Bike%204%20PIN?preview=IMG_4052.JPG)
I then took it for a 45min ride expecting it to act up at any time. On the contrary, it ran really well as good as it was before the incident maybe better. No bogging no stalling just smooth and powerful linear power with very little flat spots except maybe a little choppy in first when on an off the throttle which I believe is normal for the bike. It being NYC I didn't manage to get it flat out but I did take it to a few empty stretches of road in Brooklyn to really wring its neck and it responded well.
Really is night and day when I drove it back from the mechanic a few days ago it died 3-4 times on the short 30min ride home.
Is it really possible that it could be fixed from something as simple as cleaning the battery contacts and 4 pin connector?
If so I'm pretty over the moon!
I am planning to take it on a long ride out to Rockaway beach tomorrow so will keep you posted on how it goes.
After I got home I pulled the plugs to take a look. Here are some pics.
Plug 1
https://www.dropbox.com/home/Plugs?preview=IMG_4058.JPG (https://www.dropbox.com/home/Plugs?preview=IMG_4058.JPG)
Plug 3
https://www.dropbox.com/home/Plugs?preview=IMG_4061.JPG (https://www.dropbox.com/home/Plugs?preview=IMG_4061.JPG)
Plug 2
https://www.dropbox.com/home/Plugs?preview=IMG_4065.JPG (https://www.dropbox.com/home/Plugs?preview=IMG_4065.JPG)
Here are some pics of my old blue bimmer and my not so ideal work-space on the streets of Brooklyn.
https://www.dropbox.com/home/Bike%20Pics%20Outside?preview=IMG_4054.JPG (https://www.dropbox.com/home/Bike%20Pics%20Outside?preview=IMG_4054.JPG)
https://www.dropbox.com/home/Bike%20Pics%20Outside?preview=IMG_4053.JPG (https://www.dropbox.com/home/Bike%20Pics%20Outside?preview=IMG_4053.JPG)
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Congratulations on the fix!
I was hoping to see the plugs, but I need a drop box account. I'd rather not.
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Here we go.
Will upload these spark plug pictures directly as an attachment.
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Your engine is not running rich. The plugs look good if not on the very slightly lean side. I would say your mixture is pretty good.
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Excellent that's what I thought looking at them as well.
Weird that it was diagnosed at the mechanic as running rich makes no sense.
Hopefully this means that the fault was electrical which does seem to make sense as it's intermittent and that going through and methodically cleaning the grounds and connectors will ward off future issues.
Will post back after a good ride tomorrow to confirm if the issue is resolved.
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If your moto's rear brake cylinder reservoir hangs on the frame behind the battery cover, it's possible the tech doing the brake work decoupled the four-pin connector to have easier access to filling the reservoir; afterwards, it wasn't reconnected firmly or debris infiltrated the connection and interfered with it.
How about posting some photos of your machine?
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Hey guys,
Good news! took the bike for half day ride yesterday all over town. Took it up to speed on the BQE & Belt Parkway it's running great back to it's old self.
Can't believe the amount of time I wasted should have come here straight away. At least I know where to go in the future.
So as was stated previously what probably happened is the tech who refilled the brake fluid reservoir when the brakes were flushed did not install the 4 pin connector properly back together or got lint stuck in the connection which the deoxit fixed. The deoxit also fixed my flaky speedo that stuff is magic!
Couldn't be happier i'm planning on doing a long ride down south with my mate and his triumph. So will make sure to post a ride report and some pics we are doing the outer banks and then over the great smoky mountains to West Virginia and back to NYC is the plan.
Next thing to do is replace the grips 'one has a hole where the PO dropped the bike' and to do a spline lube as it's got 35000 miles and god knows when it was last done.
Thanks so much for all the help and here are some pics of the bike.
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Pics
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Pics
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Very nice! Looks good in that blue shade.
If your coming through southeast Pa, the area around Philly, drop me a pm. I can show you some nice local roads, and good places to eat.
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Is it really possible that it could be fixed from something as simple as cleaning the battery contacts and 4 pin connector?
Yes, and now you have your own "4-pin" story to relate at gatherings :)
It's still worth some maintenance time for the fuel delivery system, and don't forget that pesky "Z" tube behind the throttle body sensor.
Glad to hear the world is back in balance for you. FWIW, Mid-Atlantic Meet-up II is coming up on July 20th (Waldorf, MD) if your in the area.
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Very nice looking bike. That's a nice shade of blue. There are many who think the K75S is the nicest model in the classic K bike lineage. Judging from the photos, yours certainly is one of the better examples.
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Very nice looking bike. That's a nice shade of blue. There are many who think the K75S is the nicest model in the classic K bike lineage. Judging from the photos, yours certainly is one of the better examples.
you can guess where I stand on that statement!
ExpatAussieBrick,
Have fun on the trip and please post a report. The Smokies and Appalachian mountains are so far my favorite place to ride. Some of the popular roads (129 Tenn. the dragon, 209 N.C. the rattler, 16 Va. the back of the dragon, and so on) can be real zoo on weekends so you may want to plan to hit them mid week or early or late in the day. Also I see you have Metzler Lazer Tec tires on your bike IMO, I do not like them and have had poor performance from them. On my 75s they had very poor grip on wet roads and have worn out rear tires in less than 2,000 miles. FWIW I've had good luck with Avon M28s.
Sorry, Just my 2 cents that you didn't ask for.
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we are doing the outer banks and then over the great smoky mountains to West Virginia and back to NYC is the plan.
I grew up in Afton, VA. and the section of the Blue Ridge Parkway (BRP) between Humpback Rocks and Ferrum (Roanoke) is pure Nirvana (expect 3-3.5 hrs) on a motorcycle. If you're riding the southern Smokey's it's worth the ride time to go up the BRP, and cut west at Waynesboro/Staunton to get to WV. *my first moving violation for leaning, dragging peg, and speeding over the double yellow was on the BRP in the 70's ... on an awesome RD400. :)
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Hey guys,
Bit of bad news after having a great weekend riding to the beach for the 4th of July and having a blast on the bike it decided to act up again yesterday after riding home from a dinner date riding two up. The usual thing it's been doing past few weeks I was at a stop light turned green gave it throttle went to pass the cars and suddenly it lost power and barely wanted to rev to 2000 rpms I gave it some more and the engine died and we coasted to a stop. Initially engine turned over but refused to start. Then after fiddling around with the connectors again it started and got us all the way home without much more trouble besides one more incident of bucking under throttle.
I'm thinking I will remove the tank this week and take a photo of all the connections under there and clean them all up. The problem does feel electrical because it's so intermittent and the fact that cleaning the 4 pin really helped. Also thinking about checking the crank case Z hose and the throttle position sensor. I want to be able to trust the bike again before taking it anywhere far from home or on heavy traffic roads.
Kinda feeling like putting it up on craigslist while I go about trying simple fixes for it. It's just too complex of a bike for me with no real garage space or place to work on it and i've spent too much money on it to start throwing parts at it. That being said i'm not giving up yet just giving myself options.
As a clue, I did pull the plugs again after the incident and they do look a little on the lean side for sure with a light coating of white dust.
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Sounds like a classic case of four pin connectors woes to me. I have had the same thing a few times... in the end all I have to do is disconnect and reconnect the four pin and few times and everything is ok again. Have you tried cleaning the four pin connector with Deoxit or something similar?
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I agree on the four pin tank connector. A shot or two of Deoxit may clean it up enough to be somewhat more reliable.
A few owners have had some success with gently pinching the pins in the male side of the connector to ovalize them slightly so they make better contact. Others have just replaced the connector with an SAE 4 pin trailer connector, a job that requires you be sort of handy with crimping butt splices or a soldering iron.
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I sprayed the crap out of it with deoxit last night and reconnected as tight as possible. Will see how it goes today might take it for a short ride.
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I found that my 4 pin started playing up after 20 years of no problems. Sprayed it with the 2 part DeoxIT a couple of times which temporarily solved the problem. It broke down again in front of a electrical supply shop which I took as a sign that I should replace the connector. I went in and bought a waterproof connector $20.00 Au and no problems since.
Regards Martin.
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I've never had a problem with my 4 pin connector......yet, but is it a problem with the physical contact of the sockets and pins, or an oxidation problem that can be solved with deoxit or similar? It certainly could be a more robust connector. cheers.
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Every time I take mine apart, I wonder if I am breaking the connections in the plug body between the wire and the contacts. The latching tabs are so big and hard to disengage that I have to pull pretty hard on the damn wires to get it apart. On at least one bike I have filed down the dogs that the lock the connector halves together to make it easier to pull apart.
A little Vaseline smeared on the mating surfaces also helps make it easier to get the connector apart.
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Even with fitting a new waterproof connector I try to avoid disconnecting it. That's the reason why I pull the #6 fuse and not the pump connection when disabling the fuel pump.
Regards Martin.
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To get the 4-pin plug apart, try sliding the jaws of a needle nose pliers between the locking tabs and the central body of the plug, bending both tabs back simultaneously until they disengage. Then squeeze the pliers gently to grab the removable part of the connector while lifting it away from the rest of the plug. Works for me.
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Hey guys,
Some more unfortunate news so I had a go at really getting the crud out of that 4 pin and all the connectors actually under the right side cover and making sure they were snug. After I had sprayed the crap out of them I took the bike for a test ride. All appeared to be fine I took the bike for a brisk 20min ride to the local pool. After going for a swim I came back and the bike refused to start.
I kept giving it throttle and then full choke but nothing happened the engine turned over and I could hear the full pump engage but no ignition I also looked in the tank for fuel return and I could see some fuel being pumped back into the tank as I tried to start the bike. I tried reconnecting the 4 pin and plugging it back in nothing changed. So I attempted to push the bike home haha all 550lbs was sweating my butt off and I gave up when I passed my local bar and sat down for a bevie.
I was going to go into my onboard toolkit to check for spark at the plugs but very annoyingly I had lost my hex key to take the spark plug cover off. So I gave up and came back to the bike today. After much swearing and spraying everything in sight with deoxit while an old bloke from the Czech republic gave running commentary, I managed to take the ECU computer out and spray that connection and put it back. All of sudden the bike roared to life. I was super stoked to not have to push it all the way home!
What could be going on? I might go pull the plugs and check that all of them are sparking correctly. Could it be a faulty spark plug wire? Or maybe my ECU is bad? Or more likely something in the electrical system is intermittently causing the ignition system to fail. Doesn't seem to be only the 4pin because the pump was operating the whole time I was trying to start the bike.
Something I have also noticed is that the engine note at idle sounds quite rough and stumbly.
I have included a link to a video of my bikes stumbly idle. It looks fine of the tac but it sounds a bit weird. I don't remember it sounding this way before I had all my issues.
https://vimeo.com/347441343 (https://vimeo.com/347441343)
password: Brick
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Hey guys, Some more unfortunate news . . .
What's the unfortunate news? That you're not strong enough to push a moto without stopping for a bevie? :giggles It seems like you have the moto roaring to life. Is that not enough or does it roar then squeak then wheeze? Your video doesn't tell me anything is particularly wrong unless the revs are dropping but you're not closing the throttle.
What could have been going on is the FICU plug could have been making poor contact. It might not have been latched well. Pull outward on its right end and be certain it doesn't move. If it does move, its latch needs adjustment Be certain the battery connections are tight and that your negative battery cable connection on the transmission is clean and tight. If it hasn't been done already, change the feckin' fuel filter. Satisfy obsessive needs by examining the z-hose breather connecting the block to the plenum. If it were my moto, I'd replace it. It isn't costly.
(http://www.motobrick.com/gallery/2/1601-110719023446.png)
(http://www.motobrick.com/gallery/2/1601-110719023556.png)
Take the moto for a run. Bring along funds for another bevie.
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I kept giving it throttle and then full choke but nothing happened the engine turned over and I could hear the full pump engage but no ignition I also looked in the tank for fuel return and I could see some fuel being pumped back into the tank as I tried to start the bike.
I suspect that you flooded it and having an adult beverage gave it time to drain out the extra fuel. Never touch the throttle when starting, and only use the choke when the engine is cold or in cold weather. My experience with my K100RS is that some of these bikes flood very easily.
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Thanks for the advice. The bike does run quite well most of the time until these sudden episodes of rough riding which seems to have progressed to sudden episodes of no start. I think I might just be imagining a rough idle note when it is actually fine due to me not entirely trusting the bike now it's left me stranded a few times.
I will try checking that Z hose and replace it. Will make sure the ECU computer is tight as well and the battery contacts. It seemed very dusty and dirty down there.
What's interesting about having flooded the engine is that yes i'm fairly sure I probably did flood it while trying to start it and make the problem worse but after leaving it for a whole day with the plugs out it still didn't start until I went and unplugged cleaned and reconnected the FICU.
Will definitely bring some cash with me for a beer on my next test ride incase it decides to act up!
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. . . due to me not entirely trusting the bike now it's left me stranded a few times.
With the advent of wingsuit flying, parkour along high-rise buildings, and hundred-person queues in the Death Zone of Mt. Everest, the only really cutting-edge, life-threatening personal adventures remaining are sassing the police, unprotected sex with random participants and riding an unreliable moto in traffic or wilderness.
Enjoy it!
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Hey just an update for ya on the bike
So I went ahead and got a new crankcase breather Z hose and replaced it. The old one did have a crack in it near the end of the hose.
I also took the L-Jetronic computer out fully cleaned it sprayed with deoxit and made sure it was nice and snug and clipped in.
Bike has been running with no issues this past week or so.
Think this case might be closed but will go in under the tank and tidy up the connections under there to be sure.