K100RS parked for four months outside in all weathers

[Laitch]

Can you hear the pump, the four pin connector under the tank is a known source of problems. Try cleaning an reconnecting. Check fuse # 6 which supplies power to the pump.

Martin, I wish you hadn't mentioned that. I enjoy a good self-administered public flagellation. Who doesn't, really?

[Filmcamera]

Well no need to worry Laitch - I am sure there is much more wailing and beating of my breast to go yet.


Fuse no 6 is fine - the connection of the 4  pin is fine.


I COULD hear the pump when it was incorrectly plumbed - now I don't...

[Filmcamera]

and gnashing of teeth - I love a good teeth gnashing when public humiliating myself

[Martin]

Sorry Laitch. Being as the pumps are DC they will run forward or backwards with no bad consequences. Pull your pump out and apply voltage and see if it works. Sometimes if they are jammed due to a foreign body, reversing the connections back and forth briefly will free them up.
Regards Martin.

[Laitch]

and gnashing of teeth - I love a good teeth gnashing when public humiliating myself . . .
Other than those two things I am stumped, and fearful I have messed something up...

This problem sounds like it's of Biblical proportions.

I doubt if you've messed up something. It's more likely there's an electrical connection that hasn't been made, one that has not been made completely, or something simple that's been overlooked.

How many seconds have you spent trying to get it started?

[Laitch]

The fuel hose in the tank is connected, right?

[Filmcamera]

OK When the I checked the 4 pin connector for the fuel pump and fuel gauge I get voltage of approx 10v between white and brown and the fuel gauge works but when I opened up the tank and disconnected the electrical connection on the pump itself I get 0 volts.  That would seem to indicate a break somewhere from the tank connection to the pump itself.  Seems weird that I did hear the pump when the fuel lines where incorrectly connected and don't now.

[Laitch]

What's your battery voltage, currently? :giggles

[Filmcamera]

I have it on the tender but it is a little low - 11.5 at the moment


Ok when I take the pump off the bike and apply 12v it does spin but nothing when on the bike.

[Laitch]

I have it on the tender but it is a little low - 11.5 at the moment

Charge up the battery. Reconnect the fuel pump. Start up the bike.

Where do you put that battery when it's off the bike—not on a cement or stone floor, right?

[Filmcamera]

No it has been sitting on a wooden floor - but I would love to know what is wrong with a cement or stone one...

[Martin]

Check for power at the four pin connector.
Regards Martin.

[Laitch]

Check for power at the four pin connector.
Regards Martin.

He did—less than 11V.

. . . I would love to know what is wrong with a cement or stone one...

Save your love for animate objects.

. . . when I opened up the tank and disconnected the electrical connection on the pump itself I get 0 volts.  That would seem to indicate a break somewhere from the tank connection to the pump itself.Seems weird that I did hear the pump when the fuel lines where incorrectly connected and don't now.

You might have broken the connection between the sender and the pump when you disconnected the pump. Or you might have misapplied the meter, or the incoming sender wiring is wonky. Connect the pump, charge up the battery, give it another try and let us know what happens.

[The Mighty Gryphon]

OK When the I checked the 4 pin connector for the fuel pump and fuel gauge I get voltage of approx 10v between white and brown and the fuel gauge works but when I opened up the tank and disconnected the electrical connection on the pump itself I get 0 volts.  That would seem to indicate a break somewhere from the tank connection to the pump itself.  Seems weird that I did hear the pump when the fuel lines where incorrectly connected and don't now.

Can't think of any irrelevant witticisms to add to the thread so I will just offer some suggestions to help get you running.

First of all, the pump only runs when the starter is pushed, if the engine doesn't start it shuts off when the button is released.

Second, the four pin tank connector is notorious for lousy connections, especially for the pump.  It need to be squeaky clean, and in some cases(my K100RS) the female sockets need to be gently tweaked to get a better grip on the male pins.

As far as the reversed fuel lines,  I doubt that reverse flow on the fuel pressure regulator will damage it.  I know this because I have connected them ass backwards with no bad result.  Since there probably was no fuel pressure getting to the rail, there will be no damage to the injectors, they would be just about the last thing I would look at.

Test the fuel pump by disconnecting the return line from the rail and connecting a hose from the rail to a container to catch the fuel when the pump runs.  That will confirm that the pump is working and the filter and lines are clear. 

Since you had the transmission off, I would also suspect the side stand switch it will allow the engine to crank but not start, and there is no override for it.  But check the pump before going into that.

[Filmcamera]

I did look at the side stand connector - I believe the one on the 16V RS is different to the ones that were on earlier bikes.


Here are two pics of the switch, one with the side stand down and one with it up - did I screw up when reconnecting it? (not the easiest thing to photograph but hopefully good enough)

[The Mighty Gryphon]

I can't say if the switch is installed correctly.  I can go out in the garage tomorrow to check mine.  Can't say if the contact is normally open or closed with the stand up or down.  The side stand switch isn't used on the earlier bricks.  They used a retractor connected to the clutch lever.

I would work on seeing if the pump runs when the starter is cranking.  You might want to hot wire to the tank connector to override the pump interlocks and do a static pump test first.  +12V to the green/white wire and ground to the brown wire. 

[The Mighty Gryphon]

Man, am I screwed up.  Three bikes with different systems has my brain scrambled.

Just went out to the garage and checked my bike:

1.  Pump should run for a second when ignition is turned on. 

2.  Side stand down prevents pump from running. 

3.  Look at your side stand switch.

I'll look at mine tomorrow to see if there is anything I can add.

[Filmcamera]

AFter much fiddling yes it did run.  I had 12v to the green and brown was neutral and the pump ran, I don't have the greatest set of cables for this kind of thing but both my son (who was helping me) and I heard a second or two of whirring an bubbling liquid...

[Filmcamera]

The side stand switch seems a pretty simple beast, it is quite like the rear brake light switch.  When the side stand is down the circuit is open and when it is up it is closed - at least that is how it seems.  It seems maybe something with a relay maybe, I will try swapping it out tomorrow.


I can't think of anything else it can be.


The only other thing that made me pause for thought was a battery connection coming off the loom just after the motronic hook up. I could remember for sure if it was a live or ground connection but since it is black and short and couldn't easily reach the live battery terminal from where it is I am 99% sure it is a ground.

[Filmcamera]

Oh one last thing which did stike me as maybe out of the ordinary but my memory fails me.


When I put the bike in gear and hit the start button it DOES crank, I am on the center stand and can see the rear wheel move as I crank it.


Surely it isn't supposed to do that? I thought the GPI switch was supposed to disable the starter if the bike is in gear and the clutch out.

[Laitch]

When I put the bike in gear and hit the start button it DOES crank, I am on the center stand and can see the rear wheel move as I crank it.

First determine if it is actually in gear or you're getting a false gear indication and wheel movement from vibration .

[Filmcamera]

It is in gear for sure and the wheel clearly rotates about 1/4 of a turn or every time the starter motor cranks

[Filmcamera]

This morning the battery was fully charged and still no start.   :dunno :musicboohoo:


I am out most of the day with a family event but will try and troubleshoot some more later this afternoon. 

[Elipten]

Start with the basics, fuel, air, spark.  You have all those in the cylinders?  Is the fuel fresh?  Or full of water and crud?

Then compression and timing of the spark.


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[The Mighty Gryphon]

The first thing that comes to mind about the starter working is the clutch interlock switch on the handlebars.  I suspect it is adjusted wrong or has moved in the mount.  It's possible but unlikely that the clutch is adjusted wrong.  Right now, I don't think it should be high on your list of priorities. 

I have done some searches and it seems the side stand switch is a weak point.  In order to remove the transmission to work on the clutch you had to at least disconnect it which could have disturbed the contacts in the connector or even the switch mount or the lever that activates it.  THE CONTACTS ON THAT SWITCH HAVE TO BE CLOSED FOR THE FUEL PUMP TO RUN.

Find the connector for the switch, you should be familiar with it since you had to disconnect it to pull the transmission.  It has two wires on it, a green and red, and a green and yellow wire.  First, try cleaning the connector with DeOxit.  If that doesn't work, put a jumper across the pins. 

If the jumper gets the fuel pump working you could have a bad side stand switch, or it could be adjusted wrong or the lever bent.  It is a sensitive, on my bike it kills the engine when the side stand is moved even a very small amount.