Stalling engine

[jjconeill]

My 1987 k75s keeps stalling out I believe that this is a problem that has been an off and on problem. I could not get it running so took the bike to a BMW dealer who said it was the fuel sending unit, than, it's the fuel pump, than, we do not know that the problem is. than. we put in a new relay, and that worked. with new tires $1600. than I took a small spill  on my left side and cut my left hand a bit and broke my National Street Shield, all well now except the bike jerks on acceleration and dies when I come to a stop, seems like I can make it happen by wiggling the power connection and wires from the relay to the gas tank. I am not a great mechanic and especially with electronics, any suggestions, Thanks

[Laitch]

than I took a small spill  on my left side . . . any suggestions, Thanks

Dropping the bike is part of K-bike initiation.

Check that your spark plug wires are firmly attached to your spark plugs and that the other end of them is firmly attached to the coils. The impact from a fall can loosen any of the several electrical plugs under the tank, too—the four-pin plug connection under there goes to the fuel pump. You need to check your relay to be sure it is still plugged firmly into the box. Check all those after the plug/coil connections. Manuals are available in the Repair Guidance Master list. A diagram of the fuse box layout is in the K100 troubleshooting guide, also in the Master List.

[jjconeill]

thanks I thought of coils and plugs but went for fuel pump connections instead, pulled the relay and exchanged with other relay next to it, would not start, switched back and started but still stalling, I will check the plugs and connections tomorrow, thanks and will respond after that, the fall was minor, I rode an RD350 in the 1975 to 1985 era, need more practice, I needed to  turn around to get to the hot dog joint that was my destination. and made the mistake of changing my mind about what to do, pulled over on the right gravel area that had loose downhill stones front tire lost traction. live and learn, just need to repair my pride.

[Laitch]

. . . and made the mistake of changing my mind about what to do, pulled over on the right gravel area that had loose downhill stones front tire lost traction . . .

Klassic! :clap:

[jjconeill]

Thanks, new windshield my hand is healed my pride will take some time. I rode in the 75 to 85 era with a friend who had .still does, an 850 Norton, he was my idle because he never dropped his bike..

[riots100]

dirt, grit and other small foreign bodies can get stirred up and clog the fuel strainer thus starving the fuel pump of fuel to pump.  Just because the fuel pump/components where replaced doesn't mean that the tank is clean.

[wally.fisher]

thanks I thought of coils and plugs but went for fuel pump connections instead, pulled the relay and exchanged with other relay next to it, would not start, switched back and started but still stalling, I will check the plugs and connections tomorrow, thanks and will respond after that, the fall was minor, I rode an RD350 in the 1975 to 1985 era, need more practice, I needed to  turn around to get to the hot dog joint that was my destination. and made the mistake of changing my mind about what to do, pulled over on the right gravel area that had loose downhill stones front tire lost traction. live and learn, just need to repair my pride.

Clean each and every electrical connector you can find, especially those under the tank and the big plug at the battery. Wire brush works well, but disconnect the battery before you start. DAW.


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[jjconeill]

I'll check the fuel pump strainer it is new also, and the BMW dealer charged me twice for it, just finished checking plug and coil connections, took it for a ride and was fine for a while roaming around my neighborhood ready to go home than it stalled again, usually does it as I come to a stop, not the hesitation like before when I accelerate.   Thanks guys it sure is nice to have people who care to help.

[Martin]

Check the individual strainers fitted to each injector. Often overlooked. :nono
Regards Martin.

[jjconeill]

never heard of that, will do, thanks.

[jjconeill]

just had the injectors professionally cleaned, I'll have to find out where the strainer is

[Laitch]

just had the injectors professionally cleaned, I'll have to find out where the strainer is

How many of the suggestions have you followed that you've been given in this thread already?

[jjconeill]

checked connections on the coil and plugs, will check the strainer on fuel pump tomorrow, have no idea where the strainers are on the injectors, guessing where they connect to the fuel bar. thanks.

[wally.fisher]

checked connections on the coil and plugs, will check the strainer on fuel pump tomorrow, have no idea where the strainers are on the injectors, guessing where they connect to the fuel bar. thanks.

Extremely difficult to check injector strainers without damage, unless you have a injector repair kit.


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[Laitch]

checked connections on the coil and plugs,

Check the relay box for tight connections and the under tank plugs. If, like you write, you can make it happen by jiggling wires, those are the next areas to check.

[Martin]

If you have dirt in the rail or hoses new injectors can get this debris transferred into them. The filters are in the inlets and can be removed by screwing a self taper or metal screw into them and then pulling it out. This can sometimes destroy the filters. However you can back flush the injectors with injector cleaner and a 9v battery. Take due care as you don't want any sparks. Sparks + cleaner = Bigga Kaboomba. Back flush into a clean white rag so that you can see any debris ejected in the back flushing. There are plenty of sites on You tube on how to do this.
Regards Martin.

[riots100]

The pump strainer may be clear when the bike isn't running.  You need to check that there is not dirt/grit/debris in the the deep recesses of the tank itself.  Due to the recirculatory nature of the fuel system, the fuel entering back into the tank under pressure can stir up dirt and debris so that it is suspended in the fuel. (and then caught by the strainer)  When the fuel stops circulating the debris settles back to the bottom of the tank.


It isn't enough to just check the strainer, you need to look deep in the tank itself.

[jjconeill]

Good Afternoon, another beautiful day here north of Chicago. as  well suggested decided I would check my screen filter on the fuel pump but as I was apprehensive of doing so without much experience, as last time I pulled the pump it was hard to get back in. So decided to focus on what I believe is wrong, having direct access to the troubled machine that's what I did,  so I opened my gas tank lid used a screwdriver to hold flap open put my ear to the hole turned on ignition, and started engine, I could hear the pump running, than reached down to touch the electrical connector that allows the disconnection of the tank power, squeezed the tabs and the pump cut out, and within a few seconds the engine died. So how do I fixit? the connection from the tank should be new as the dealer replaced the sending unit I assume as they charged me 300 so can I replace the wires to the relay ? checked MAX BMW but saw no such wires other than the Frame wire harness. Guess I need to find a used one. do you think it would be hard to change. Again thanks so much, and GO CUBS!

[Scott_]

That 4pin connector can easily be replaced with the flat four pin connector you find on small trailers. It is durable and weather proof.
It does not have to have the BMW stamp of approval.
Should be readily available at autoparts stores and some *marts in the automotive section.

[jjconeill]

that sounds great, I do have some experience with molex connectors working with PCB's, first I think I should do my best to clean the connections, they look a little dull, will do that tomorrow. Took a ride despite the problem and the bike would die at times, than roar back, pump is getting erratic power. Then it died and would not start on a winding road in Wisconsin, pulled over to a house and after a while decided that I was low on gas, even though my odometer gas gauge said otherwise, went to a house where a man was in his garage with a 5gal empty can, he gave me a ride to gas station and all is well, home now with a full tank and a solved problem, Thanks everyone, another exciting day with my k75

[MIbrick]

Dropping the bike is part of K-bike initiation.

I was creeping in to the driveway after work yesterday and clamped on the front brake a little more than I had intended, what with the bars hard right and all.  Down went the bike, gently though still hard enough to pop off the right mirror.  Getting the mirror back on was a PITA, but I did it.  After checking the bike over and reassuring myself all was well, I thought, "It'd be funny if that fixed the GPI."  Came home for lunch today, beautiful day out, decided to ride the bike back to work. The GPI is fully functional again.   :dunno2:


jjconeill:  I don't really advocate this, but hey, maybe a little "percussive maintenance" on your bike would put everything right again?

[johnny]

greetings...

ran out of gass... thats gonna be filmcameras next drama since he already dropped it...

j o

[jjconeill]

Well thought I had the problem fixed, cleaned  the contacts on the connector, and off I went to play Disc Golf. But it did stall again after a few miles, then would not start. on a country road in Wisconsin. in desperation I cut the connector off and twisted the wires but nothing, after only 30 miles on a full tank it seemed low, may be leaking, went to a house and a nice old couple gave me some gas, it took about two gallons, but still would not start. called tow truck and it's back in my garage but will not start, anyone want to purchase a nice bike? I told my wife I will sit on it in the garage and put Born To Be Wild on the stereo. 

[jjconeill]

bike is home and sitting in the garage, I let it sit about a week wondering what to check. as suggested  I wanted to check the screen under the fuel pump, put my hand in the gas tank and found the hose coming from the pump not connected pushed it back on and started and ran perfect. so was the hose loose was the connector really faulty? we may never know the answers to life's questions. 42. thanks for all the help, going riding today, watching for rain.

[Laitch]

I wanted to check the screen under the fuel pump, put my hand in the gas tank and found the hose coming from the pump not connected pushed it back on . . .

That hose needs a fuel injection style clamp on it. Was one installed on it and did you tighten it?