Polarity at fuel pump

[Leo]

1985 K100RS   This bike sat for 14 years. Cleaned fuel tank, new pump, filter, hoses, serviced injectors, full service.  Does not start. The fuel pump only when the starter button is depressed and then it runs backwards, does not run when the switch is on without starter button depressed.  If I run 12v directly to the pump it starts and runs normally. What am I missing?

[mystic red]

What "starts and runs normally"? The pump or the bike?

[jakgieger]

Welcome Leo

1. Post a picture of your bike
2. Put a donkey in your uploaded avatar
3.  Do your do diligence...

Just kidding :dunno...the natives here are very restless.  I was exactly where you are last year and had a very similar post .  Natives were not quite so restless at that point and I got some good help.  Here is the thread. http://www.motobrick.com/index.php/topic,7174.msg49572.html#msg49572 Pump does NOT run until you push the start button.  In the thread are the links that will speed you along.  You need to thank the guys and get that donkey avatar up :hehehe it's becoming quite the fashion.  Sorry for the intro, but I think that I have developed Stockholm Syndrome from hanging out here :yippee:

[Laitch]

What am I missing?

Welcome, Leo!

What you're also missing is that every electrical plug and connection on a bike that's designed around electronics and that's been idle for 14 years needs to be cleaned and tested, including the ignition switch and the starter/kill switch module. Was that included in the "full service?" You've missed defining in your post what "full service" means. You've probably missed consulting the troubleshooting flow chart in the Technical Library.

An airhead might start with no problems after 14 years but a neglected K-bike is likely to need a lot of attention from its owner. You might need to replace every relay but you can test them for function first.

[Martin]

If it is running backwards you could have the wires crossed. You should not be able to do this as the terminals and the terminal posts are different sizes. But a lot of Bricks now have after market pumps so the wiring might have been modified.
Regards Martin

[Leo]

The motor fires up and runs normally when I jump 12v directly to the fuel pump. Have cleaned all connections. Will check switches and relays Mon. Do not understand why I get 12v at the ground wire of the pump when the starter button is pressed. I am not real handy with electrics but can usually work it out. Thanks for the help.  Leo

[The Mighty Gryphon]

Welcome, Leo.  It's good that the engine starts and runs ok with 12V direct to the fuel pump.   That means the problem is in the fuel pump wiring which includes the relay.  I don't have my schematics handy, but there are others more knowledgeable than me on these things anyway.  You should be hearing from them soon.