BMW K75 - Won't start with fuel pump connected

[Laitch]

I purchased the fuel pump rely and fitted that, which seemed to fix the grounding issue but the motor was then locking up with unburnt fuel.

Congratulations on getting the engine to run! Can you explain what locking up means? I can't understand what installation of the relay fixed.

It seems Scott_ 's assessment of the underlying cause was the correct one.

[daveson]

Yep, I'm thinking the exact same thing, which made me think, try harder to stick to my promise. 

[liam.adv]

same problem, solved by replace L-Jet box.

Hello,

I am wondering if anyone can help me.

I have a 1987 K75 which I am turning into a cafe racer. I have built this all back up from the ground up, with new parts.

When the tank is all plumbed in and the electric connector connected.  I press the starter and here to fuel pump prime the system. The bike just turns over and will not start.  However, if I disconnect the 4 pin electrical connector the bike will start up and runs a dream until all the fuel is used etc.

I can repeat this process over and over, plugging the 4 pin back in priming the system, disconnecting the 4 pin and the bike starts up and runs fine until the fuel in the pipe and rail is used.

Please can someone assist as I am lost as to why this is as I am at my wits end.

-- 4 pin connected - Won't start --


-- 4 pin disconnected - Started --


Regards,
Johnny

[Cafe racer]

Happy ending...