1990 K75S dies about 10 miles into a ride, revives if shut off for a couple min

[Redbetty]

I bought a 1990 K75S last August with 11,000 miles.  I've put 3,000 trouble free miles on it until recently when it started to die 5-10 miles into a ride.  If I turn it off for a couple of minutes it's fine for another 5-10 miles.  It's worse if I'm giving it lots of gas to get up a steep hill.  I took it to dealer and they cleaned fuel injectors, checked fuel pressure, checked for air leaks, cleaned corrosion at fuel pump electrical connection.   it's got new plugs and a new fuel filter 2000 miles ago.  They ran it and said it ran fine but for me it's doing exactly the same thing, I think they just didn't take it out for a long enough ride.  When it happens it acts like it's running out of fuel and runs slower and slower missing more and more until it conks out.

I'm a newbie without a lot of mechanical skills, but it will get expensive very quickly trying to have the dealer fix this intermittent problem.  To me it seems fuel or air related.  Any advice would be much appreciated!

[Scott_]

Well, at 5-10 min into a ride, then it repeating after it cools off, sounds to me like it could be the hall effect sensors getting hot.
You can test this in your driveway. Bike on the center stand, start it, and use a hair dryer or heat gun on the sensors to get them hot.
They are behind the 'T' shaped cover at the front of the engine.

Could also be fuel pump, or fuel pressure regulator getting weak and failing while running, even though you said the dealer checked them.
You will find, as many others here, there are not that many dealer mechanics around anymore that actually have any hands on knowledge(experience) or "know" anything about these 20+ year old bikes. Not that there can't be, they are just becoming fewer and fewer.

[harper]

My friend had the same symptoms on his 89 k100. I replaced the Hall Effect and the bike ran like a new one. The same thing and symptoms were happening on a 81 R100RS. Sit for 10-15 mins and go down the road another 20 miles till it stopped again!!! I replaced the " Bean Can" and all was fine..................

[Redbetty]

Scott and Harper thanks much for the advice!  I'm out of town now but when I get back I'll look into that and see if it fixes the problem.  Thanks again!

[RobP]

Has anyone got a current source for the replacement Hall Effect sensor units?   I've seen a lot of threads here and elsewhere that reference NLA part numbers and suppliers. 

[Novafrk]

Is this a common enough failure that you guys recommend changing on these old bikes? Should I get one to keep in the tool kit for when it does go bad?

[Chaos]

They are pricey little buggers, $419 at beemerboneyard.  Still have the original in mine, 28 years and 180k plus.

[Novafrk]

OUCH! So they don't go bad often?

[Chaos]

It's a crapshoot.  Some go bad some don't :dunno2:

[RobP]

There were some threads elsewhere that talked about just replacing the sensor components with new ones.  They used to be made by Honeywell but the part seems to be NLA.  There are some replacements being offered in Germany at http://www.cy-sensors.com/Hall-Vane.htm.  I believe the K100s would use their part CYHME56 or CYHME56C.  If I understand their pricing charts, the cost on these is about 12 or 15 Euros each, plus shipping.

I was wondering if anyone had found the updated Honeywell part numbers, or other replacements in the USA.

[Popetrout]

I just replaced my hall sensors with the above link http://www.cy-sensors.com/Hall-Vane.htm. , they are by far the cheapest and fastest.  $80 total for my k1100 received UPS in two days, but I think the sensors are different on the k75 and k100's.  Takes a skilled hand to drill out the old pins and re tap them in, also a little soldering.  There is an USA company that sells them but I can't find my old post with the info, they charge $100.

[rbm]

Check Ebay item #301569084934.

[Chaos]

You say it's worse if going uphill.  On the off chance it's not the HES, maybe water in gas tank?  Pickup is in back of tank.  Change the filter (one bad fill up can plug the filter) and add a can of HEET.  There's a thread somewhere on suitable gas filters from Autozone-etc.

[Scott_]

There's a thread somewhere on suitable gas filters from Autozone-etc.

NAPA Gold 3032 fuel filter for about $4 or less.

Thread is in the Lieberry-- Alternate parts list..

[EpsteintheSwami]

Had these same symptoms on an old bike due to the vent in the tank cap being clogged, seems obvious but worth a check if you haven't already

[Redbetty]

EpsteintheSwami I think you might be on to something.  Had it out today with the hair dryer, didn't seem to make it run better or worse with the HES hot or cold.  However when I opened the gas tank cap it ran better.  I assume you mean the foam filter that can be removed when I remove the lock with the 3 phillips screws?  If so it looks pretty grungy so I bet that is the problem (I hope).  I'll see if I can get a new one or clean that one up and hope that fixes the problem.  Will keep you posted, thanks!

[Redbetty]

Delayed update on the above problem.  It wasn't the hall effect sensor.

Turns out that it had some gelatinous material in the tank that had fouled the fuel injectors.  Cleaned the tank, replaced the fuel injectors with reconditioned ones, replaced the plugs and wires and it's been running like a champ ever since.  Appreciate everyones help and suggestions.

[The Mighty Gryphon]

 :clap: