A long time since I posted last, bike has been on work bench for 2 years work has been done on lots of small things now starting on a paint job. So tried starting, new battery new fuel lines and filter  tank had been off for paint strip fresh fuel bike turns over freely no sign of firing, checked fuel line to injectors nothing. I know there is pressure in fuel line when working and there's a sound from fuel pump that something is happening, but I'm wondering how do you prime the system or is there  a way of  dealing with this. The bike has performed well over the years and is in good condition and well looked after. Thanks Coopz

Have you disconnected any of the hose connections in the tank to see if there is a blockage in the filter or one of the lines going to it?

Is there a loose connection in the tank that is letting all the fuel from the pump leak?  This has happened in the past to others.

Be sure you have either a neutral green light or clutch lever pulled in.

Yep have checked all connections fuel lines tec just on the tank internals my K100 is a 1985 with a single bolt down at rear, the downloaded manual I have seems to have a float level indicator in the image mine dos'nt did the later models change just curious thanks

The tank internals changed with the change from the bolted down tank. You cannot fit a fuel gauge to early ones. Only the later ones have the float arrangement.

You seem to have the wrong manual.

Any chance the hose connections to the front of the tank are reversed or the hose connections to the fuel pressure regulator are reversed?

Sorry for dragging this out but should you have a full 12 volts at the fuel pump, just put voltmeter on to check and I'm getting around 7 volts when I hit the start button? Battery is fully charged fuel pump clicks when ignition is keyed off, do you think the pump is cactus. no sign of fuel coming out of fuel line to fuel rail.

Pump could be blocked too, reverse the polarity and try it, running it backwards may free it but to be honest if it sat like that consider the possibility it is cactus. Given their reputation its advisable to have a spare in your shed. Most of the reputation comes from being a pre ethanol bike and also the risks from sitting causing ethanol related damage to the pump damper and mounting. That same pump is in millions of cars around Europe [Fiat Peugeot Lancia VW] and regarded as reliable in the cars so they are very readily available.

Get a wiring diagram of the early K100;  https://mega.nz/file/ymhGkLbI#vR33x-42yP5ysLDxMgC63YcZBpMaLmw5OcXVBDg3kCU

Many thanks for replies pump is not pumping at max pressure got it to work by reversing polarity surprise surprise made a hoorible sound so new one ordered  everthing seems to be where it should be so hope the buggar starts when I get the pump. Thanks

I started my K100 RS up after a 15 year sleep. Took off the tank and took all the internals out and threw them in the garbage.Cleaned the tank and installed all new in it,put on all new fuel lines ,pressure regulator,cleaned all 4 injectors , made sure all the electrical connections were good and put in a new fully charged battery. Also gave it clean oil and filter.It started like it was running an hour ago ! Ran it on the center stand for 5 minutes then changed the oil and filter. That was around 16,000 miles ago back in Oct of 2017. Took some tweeking at first but was able to travel on it in 2018. I find it easier to just replace everything up front than fooling around with old stuff when bringing a bike back from the dead.

I think you'll find that 7 volts won't be enough to drive the pump at full pressure. Check your fuel injection relay is working ok and that the connector is clean. Good luck.

Holister wrote:I think you'll find that 7 volts won't be enough to drive the pump at full pressure. Check your fuel injection relay is working ok and that the connector is clean. Good luck.

On some Ks the horn relay is the same as the fuel pump relay and they can be swapped.

If your cylinders are dry sometimes these girls just wont fire, If you shoot a couple of cc's into the spark plug hole she may just accommodate your wishes and start.

https://www.youtube.com/watch?v=DerHlx-bO0s

If you have it, Automatic Transmission Fluid or Marvel Mystery Oil works even better as it has additives that act like penetrating oil and carbon deposit softeners.