Hi everyone, I bought my 1987 K100RS and at present I have it pulled apart to paint. The previous owner tried to paint it with a rattle can and made a big mess. Luckily he left the tank alone. I have spent hours on this site reading up on everything and have given the bike a service and put a K&N air filter in and changed the fuel lines. My problem now is it wont start so I'm retracing my steps to see what I have done wrong. Any ideas??????

Have you plugged the fuel pump connector in. Comes out under the tank and goes down to a 4 pin connector.
Fuel pump should run when you turn the ignition on then touch the starter button and stop 1.5 seconds after you release the button if the engine is not running.
It's an easy trap.

And welcome to the forum.

RicK G wrote:Have you plugged the fuel pump connector in. Comes out under the tank and goes down to a 4 pin connector.
Fuel pump should run when you turn the ignition on then touch the starter button and stop 1.5 seconds after you release the button if the engine is not running.
It's an easy trap.

And welcome to the forum.

Thank you for your reply and adding me. The fuel pump runs and even after I run the starter it continues to run without the engine running, could this be a pressure problem? I will take the tank back off and see if I have missed something. The 4 wires have been cut and joined to get the tank off easy. I intend on replacing the joiners that have been put on there. I bought a SSB lithium battery for it on ebay the listing said it would suit a K1300, it runs out of puff in about 5 seconds flat so I put the old battery back in with no change. I think it is only 12 amp hr. and 290CCA. Do you need a 20+ amp.hr. to start it? 
Also Rick have you got a link to your K75 GS ? What parts you changed etc.? And photos...Thanks

blacKbricK wrote:The 4 wires have been cut and joined to get the tank off easy. I intend on replacing the joiners that have been put on there.

Welcome, blacKbricK.

Can you post a photo of this joinery? 

Usually, four wires are attached to a connector which mates with another 4-wire connector. The purpose—among other things—is to allow removal of the tank. If you have four individual connections—that's not clear to me from your description—I'm guessing you've misconnected some of them.

Has the bike ever run since you've owned it? How long have you owned it? How many miles have you ridden it?

Laitch wrote:

blacKbricK wrote:The 4 wires have been cut and joined to get the tank off easy. I intend on replacing the joiners that have been put on there.

Welcome, blacKbricK.

Can you post a photo of this joinery? 

Usually, four wires are attached to a connector which mates with another 4-wire connector. The purpose—among other things—is to allow removal of the tank. If you have four individual connections—that's not clear to me from your description—I'm guessing you've misconnected some of them.

Has the bike ever run since you've owned it? How long have you owned it? How many miles have you ridden it?

Yes the bike was running up until I pulled the fairing and everything else off it.The wires are joined to the same colour as they came apart.

If there is no connector then use a 4 pin automotive type plug. The wires should exit from under the rear of the tank then go over the right frame rail to the 4 pin connector. it may have been removed as they are troublesome things. Those pumps will run backwards if the polarity is reversed and pump nothing, it's worth a double check especially if the pump has been replaced by an aftermarket type.
The K75GS has been shelved for a few months due to engineering compliance problems and may never be as I wanted. When it's done it will be shown but not before.

Check the multi pin plugs on the ECU (under the tool tray) and ICU (behind the steering head below the top rail) are firmly pushed home but if as you say the fuel pump is running all the time then I strongly suspect a wiring fault or a plug in the wrong place.

You have probably had the air filter box off so check that the large tube to the plenum chamber above the fuel injection throttle bodies is connected correctly and not leaking a heap of air. Also check the wires from the top section of the airbox are still plugged in firmly.

Thanks a lot for the info. That's what I'm in the process of doing at the moment.

If it won't start then it won't start whatever battery you fit. I have a quarter size Yuasa YTX 14 in my K100RS 16v and it has no problems starting the bike. 
I have a Lithium in the Ducati which weighs in at 600 grams and has no problems starting that big twin either.

BobT wrote:If it won't start then it won't start whatever battery you fit. I have a quarter size Yuasa YTX 14 in my K100RS 16v and it has no problems starting the bike. 
I have a Lithium in the Ducati which weighs in at 600 grams and has no problems starting that big twin either.

OK thanks for the info. I think this battery is equivalent to the YTX 14. It weighs a bit over 1kg I think. Me not being an Auto Electrician I thought I would ask the question about amp hrs. Thank you.

It's be a good idea to pull the spark plugs as well to check for fuel... wet/dry.
Pull one of the injector connectors. you should get 12V on one of the female connectors inside the plug.

Holister wrote:Pull one of the injector connectors. you should get 12V on one of the female connectors inside the plug.

Would like to add: ...only when you press the starter button, or the engine is running.

I think you picked me up on that once before Inge. You'd think I'd learn. Thanks again.

Thanks to everyone for their input. I will let you know what I find.

Holister wrote: I think you picked me up on that once before Inge. You'd think I'd learn. Thanks again.

Good Luck...........next time.

blacKbricK wrote: The fuel pump runs and even after I run the starter it continues to run without the engine running, could this be a pressure problem?

That isn't normal, if the pump runs all time the ignition is on.
The pump should only run when you press the starter button
(and a couple of seconds after) and when the engine is turning.

I would guess some wires have been mixed, the relays contacts
is welded shut or a wrong signal to the relay.
The signal to the relay is coming from the ignition ECU which
grounds the relay coil, if this wire is damaged so it contacts
the frame the pump will run continuisly with ignition on.

Inge K. wrote:

blacKbricK wrote: The fuel pump runs and even after I run the starter it continues to run without the engine running, could this be a pressure problem?

That isn't normal, if the pump runs all time the ignition is on.
The pump should only run when you press the starter button
(and a couple of seconds after) and when the engine is turning.

I would guess some wires have been mixed, the relays contacts
is welded shut or a wrong signal to the relay.
The signal to the relay is coming from the ignition ECU which
grounds the relay coil, if this wire is damaged so it contacts
the frame the pump will run continuously with ignition on.

OK thank you. I will check it out again tomorrow.

Well....I finally figured out the problem....I had the fuel lines around the wrong way. Swapped them around and it fired up straight away. Thanks to everyone for their help.