No Spark on '85 KRS

[KzooKRS]

Hi There -

Just pulled my '85 K100RS out of 18 month hibernation over Memorial Day weekend. Bike has just over 59K on the clock, bought 4 yrs ago w/ 44K.  Was a bit molested, but over the course of time I've cleaned up, replaced consumable parts, generally brought into much better condition (from reading here & on ADV rider).  Battery was out of bike and intermittently on tender during the siesta..  Amazingly, fired up after a dozen or so very ginger pokes on the starter and after a few minutes settled down to a nice smooth idle. Gave it a half can dose of SeaFoam just because. Brought it home a few days later and three days ago took a 165 mile shake down loop. Topped off w/ Super Shell and rest of the SeaFoam. No issues, ran purrrfectly.  What a great reliable scoot!!  Yesterday went out for another loop.  Bike running great and was about 80 miles in when I rounded a corner waaaaaay out in the boonies and it died. Dead.  Coasted to stop.  Hit the starter which worked fine, but no spark.  Lights, clock, horn fine.  Ck'd battery connections, fuses, leads from the coil and for fun pulled & reseated the big DIN plug to the ECU under the seat (learned that a few years back).  No joy.  After a few minutes it became apparent the smartest move would be to use the tow insurance I'd added a few years back.  $115 after the $100 insurance coverage and a 55 mile ride back in the cab of the flatbed & I'm home. (Driver was a HD jockey, but didn't laugh....... too much at the BMW).

So ......  Any ideas on where I should start & what I should be looking for would be greatly appreciated.  Am attending the Gilmore Antique Motorcycle Show sponsored by local BMW club tomorrow, so will be asking those folks too.

Thanks.

TB

[mystic red]

1/2 can of SeaFoam seems like a lot. One ounce per gallon is the recommend. Have you pulled a plug and confirmed no spark?

[KzooKRS]

Haven't pulled plug yet, but will confirm.  Thanks.

[mystic red]

Can you hear the fuel pump pressurize when you turn the key? Does it have a sidestand switch? If so try bypassing it.

[KzooKRS]

Plan to ck the fuel pump pressurization and spark later in the afternoon.  Will report back.

Thanks.

TB

[Inge K.]

A -85 got Jetronic....then the fuel pump starts when you hit the starter button, and it ain't got a sidestand switch.

[grant71]

Similar happened to my K100 a few months back. Problem was fuel level sensor. No electric to fuel pump which is via sensor

[mystic red]

and it ain't got a sidestand switch.

Thanks Inge, I didn't know.

[Big_B]

Maybe check out the fuel filter too. I've had to change mine several times when I first got my K1100 to catch all of those little gooballs in the tank from sitting for 8-9 months. Now I carry a generic 5/16" filter and long flat head with me just in case.

Good luck with it and make sure to keep us posted.  :2thumbup:

[KzooKRS]

OK - a couple of things.

No buzz of fuel pump when I tap the starter button.  I am aware of the fuel filter issue, changed mine out a couple years ago and was the reason I gave the gas a big shot of SeaFoam - just in case I got a big glop of something in the tank after sitting.  BTW - did you all know that Beemer Boneyard did have in stock the orignal spec filters for 85 KRS - w/o the fuel breather line - so it's just a round basket?

Pulled #1 plug, reattached the wire, let sit on the engine block.  Hit the starter.  At first I thought there was no spark, but upon looking *very* closely, there was the most pitiful spark I've ever seen.

Does this help diagnose?

Thanks bundles.

TB

[Inge K.]

Since the fuel pump doesn't start when you push the starter button, the next step would
be to check if power is present.
The fuel pump connector you find under the tank, at the front left corner....
measure if you got power at the green/white wire, when pushing the starter button...

If you got power...the problem is the connector, pump or ground connection.
If no power is present ...the problem is the relay, it's connections or signal.

[KzooKRS]

I'll give it a try tomorrow. 

Thanks.

TB

[KzooKRS]

11.9v at the Green/White connector under the tank.

If this requires a replacement fuel pump, will the NAPA/Mustang pump listed as a substitute for K1100 work or is there a different part#.

Thanks for all the info.

TB

[Inge K.]

Before pulling out the pump, you could try to run it directly from the battery (smallest terminal is +).
......To rule out a bad connector, or a bad ground.

[KzooKRS]

Got it.  Will do.

Any word on substitute if needed?

Thanks.

TB

[Inge K.]

Any word on substitute if needed?

No experience with the different available pumps at your side of the pond, others have to answer that one.
But have a look at Euromotoelectrics.......you got a 52mm pump.

[KzooKRS]

Inge K. - thanks so much for you help.  Much appreciated.

Any takers on that substitution?

TB

[WayneDW]

Here is an ebay seller who puts together a substitute fuel pump kit:
http://www.ebay.com/itm/BMW-K100-fuel-pump-K75-fuel-pump-brick-K100rs-K100rt-K100lt-K75rt-K75s-/380654965898?pt=Motorcycles_Parts_Accessories&hash=item58a0cdd48a&vxp=mtr
I haven't bought one personally, but I pointed it out to another guy here who did.  We haven't heard from him yet on how it went (that I've noticed).

[KzooKRS]

@WayneDW -

Thanks for the info.  Will be end of the week before I have time to get back at this, but will report back as soon as I do.

TB

[Scott_]

I've done the Ford FP in my '97. IIRC, the challenge was filling the void between the smaller diameter pump and the larger diameter rubber damper mount.
The pump came with a short piece of fuel line that I cut to fit around the pump to fill the gap.
It is most definitely quieter than the original pump and I've not had any other issues with it.

Kzoo, like Inge suggests, test the pump direct to the battery. Just BE CAREFUL working in the tank, don't poof yourself.

There have been times when the pump circuit conductor breaks where it passes into the tank at the level sender mount. The only way to resolve that is to replace the level sender unit as the electrical is molded to the plate.

[KzooKRS]

Thanks for the info Scott.  I'll get the NAPA pump in the next day or so.  I had to replace the fuel filter the first year I had the bike ('09), so I'm a bit familiar w/ working inside the tank.  I have a pump & will pull out all the gas I can.  Just checked my spares and I have a fresh fuel filter, so I might as well replace that while I've got everything apart.  I'll report back over the weekend when I've had a chance to work on the bike.

TB

[Inge K.]

About testing the fuel pump when its still in the tank, make some good connections at the pump first
......then connect at the battery......away from the tank.

If you find out that the connector is the problem...it's usually the female connector that have become
to wide.....use a couple of toothpicks (or other fine pointed instrument) to press them back to shape.

If the connector is beyond repair, you can use the one for the factory alarm system (identical) which
you find in the relay box.

[KzooKRS]

Thanks again!

TB

[Michael in AZ]

There have been times when the pump circuit conductor breaks

I'm having pretty much the same issue on my '92 K75RT. I replaced the OEM pump with the Herko about a thousand mile back. No problems. All of a sudden I noticed some slight intermittent lag on the throttle. Then, bam. No pump when I went to start the bike. Starter and motor running just fine (I tried from 1st and let clutch out confirming motor is turning over). I've pulled the pump and jumped directly from the battery. Pump is fine. No fuse issue at the box. Took the battery covers off and the connector to the tank lead is clean and does not seem to have problems visually. But still no juice to the pump. Keeping in mind that I am a complete newb in all things moto (and mechanical for that matter). How would I test to see if the pump circuit is out? Any and all help is appreciated. One thing about my first moto being a 20 yo Brick -- I am getting to learn all the time about how to find and fix the minor stuff!

[Scott_]

There have been times when the pump circuit conductor breaks

I'm having pretty much the same issue on my '92 K75RT. I replaced the OEM pump with the Herko about a thousand mile back. No problems. All of a sudden I noticed some slight intermittent lag on the throttle. Then, bam. No pump when I went to start the bike. Starter and motor running just fine (I tried from 1st and let clutch out confirming motor is turning over). I've pulled the pump and jumped directly from the battery. Pump is fine. No fuse issue at the box. Took the battery covers off and the connector to the tank lead is clean and does not seem to have problems visually. But still no juice to the pump. Keeping in mind that I am a complete newb in all things moto (and mechanical for that matter). How would I test to see if the pump circuit is out? Any and all help is appreciated. One thing about my first moto being a 20 yo Brick -- I am getting to learn all the time about how to find and fix the minor stuff!

Something easy to try first, I had this happen to me with my '95, unplug/re-seat the multipin plug at your jetronic/motronic unit.

If that doesn't work for you then next check for fuel pump power at the 4pin connector at the rear of the tank behind the right side cover. The fuel pump power feed should be the green wire, brown will be your ground. Those connectors have been known to go bad from dirt and oxidation. If you read/measure good power at the connector and you still have no pump, chances are that the green wire is broken/intermittent break where the wiring enters the tank thru the sending unit body. The only way to remedy that is to replace the sending unit assy.