Hi all, 

my k100 fuel pump does not prime when the ignition is switched on.

Any ideas anyone ?

Pump output is good and she pulls all the way to the redline.

Bob

audibob wrote:my k100 fuel pump does not prime when the ignition is switched on.

That's normal on a Jetronic equipped model......the fuel pump starts when
you hit the start button.

Thanks for the info Inge.

I assumed the pump should prime when the key is turned.

Bob

It only pumps when the engine is turning. The 4 valve Ks do prime the pump for a few seconds when the ignition is turned on though.

The reason for this post was during my recent 1100 TB swap I checked the fuel pressure .

With the gauge in place I switched the ignition on and before I hit the starter button,  I heard the pump run  and it primed the system . 

That surprised me to say the least as I have never heard it prime before or since . 

If my pump is not supposed to prime, how did this happen ?

Comical answers will be expected and duly accepted 

Bob

Obviously the 1100 TBs gave it ideas above its station before it woke up to itself.

(Ask and Ye shall receive.). 

Bill

Thanks Bill..

You could be right ...

But I know what I heard...

Bob

Is the harness original, without any "owner modifications"? Anything is possible if modifications have been performed on the wiring.

Hi Robmack, 

The only modifications to the wiring I saw was  bullet type crimped  connectors to the ignition switch cable at the 

rear of the tank instead of the normal multi block type.

Not sure why that was done. 

Apart from that the loom looked okay.

Bob

Sry to piggyback, but I have a similar thing.

I removed the tank on my two week old 1985 K100RS. I was changing coolant and dealing with weird wiring. I also was starting to clean a bit around and under the throttle bodies. The caps on the bodies were bad or missing, so I replaced them. I bypassed the BMU. I attempted but did not succeed with pin 7 on the flasher unit, but I went around it to get the non-working side blinking.

Put all back together. Power switch, lights, turn signals all work.

When I hit the starter, I hear the fuel pump, but engine does not turn over.

Did I dislodge a wire under the bodies, or something?

TY all