View Single Post
Old 09-16-2012, 05:04 AM   #221
Dr_Bean OP
Joined: Jul 2004
Location: The Netherlands
Oddometer: 111

I will answer all PMs asap.... I Just came back from the Balkan rally:

about the fuelpump: "how it works"

You are almost correct:

1st of all:
The ECU (the electronic control unit, located below the 'glove-box') in the bike switches the power to the fuelpump ON after you turn the ignition key (+killswitch) to ON. It does this through the fuelpump-relais. IF the engine is NOT running, the ECU will turn this power OFF again after 5 seconds, and only ON again when either the engine starts running, or you will turn the killswitch/key OFF-and-ON again.
This is a safety in case the engine is not running, but fuel would be leaking out of the carburetor because e.g. the bike is on its side...

This is all KTM-original, and has nothing to do with my kit/electronics.

My kit is IN the pump and just replaces the function of the contact breakers.

How the pump works:
the pump is a diaphragm pump, which works a bit like a hart.

A coil/solenoid pulls the pump-rod 'out' when it is activated (current flowing through it) and makes the pump-chamber suck fuel IN.
When the pump-rod is almost at its end the contact-breakers OPEN, and de-activate the solenoid.
A spring in the pump now pushed the pump-rod back, emptying the pump-chamber towards the carburetor.
The carburetor has a normal floater: When there is enough fuel it closed the fuel-line. This means the pump will NOT empty and the pump-rod will not run back.
Only when the pump-rod is almost back (spring decompressed) the contact breakers will close again and re-activate the solenoid/coil. starting over the complete cycle.

My kit replaces the contact breakers and:
- detects the position of the pump-rod with an optical detection: activating the coil when the spring is fully decompressed.
- switches the main-current of the pump with and electronic switch (power mosfet)
- includes a damping diode to avoid power spikes, and
- it also activates the pump 1x per 2-to-3 seconds anyway (even if the pump is not empty): this is a safety run mode: When EVER the optical detection would fail, e.g. because it would be dirty, you still get some fuel, enough to run 40mph and get home/to a garage: clean the optical detection and it should be ok again.
Myself, I was the only one to ever experience the need of this, after I completely flooded the pump with mud-water, after getting to s stand in deep water for quite some time :-) ....

Hope this clarifies: feel free to ask!

Dr_Bean is offline   Reply With Quote