Anders M,
Glad to see you got a good result.

Regards Titus

Now I have cleaned the pedal assy and it now seems to work fine and it also has extra power :) but knock knock on hard wood! Thanks for all help

Ok I will chek out the accelerator pedal assembly and see if I can find the problem there.

well you may have answered your own questions

"Every time the forklift have not been used in a while it has this jump start problem, but after 5-15 kicks on the throttle-pedal it is working normal."

sounds to me like something in the accelerator pedal assy? or there abouts? high speed switch sticking? loose connection?
I'd check that out

Model: Yale 1977, BELT30-77
Serial: UK-058

It is four cards, I took every one out and looked for damage, but nothing to see.

Every time the forklift have not been used in a while it has this jump start problem, but after 5-15 kicks on the throttle-pedal it is working normal. So for me it seems like something need to get hot before it is working normal. And when it is working it dosen't suddenly start to fail, then it is ok until I live it for a while and the same thing over again. No differns if I unplug battery or not. For a little while a thought it had something to do with the ignition key, but it dosen't seem to be a connection there since it works after i while without touching the ignition key.

I can take pictures if that's needed.

Here is the link again:
http://www.youtube.com/watch?v=Gc1Qp-MTcyQ

anders_M,
first things first
can you give us a full model and serial number?
also if you can see the control panel and the logic card, can you tell us what it is?

many things can cause the truck to jump like this but we need more info to help determine what it might be.

Anders M,

This is due to the electronic system fail safe. System being activated, when the direction contact pulls in to drive the truck If the system detects a fault it blows the contact out and the truck appears to leap, there may be a short on the wiring or the logic unit may have failed a board component may be failing possibly one of the three thyristors has failed or one of the flywheel or braking diodes has.
The system on this truck is known as the mark v second system,
If you take the lid of the logic unit you will see that the unit comprises of a base board with four other boards plugged into it also several relay assy all these can be removed carefully to be examined for burnt out circuits,
Check the shorting contractor make sure it's not stuck in as this would also cause this problem.

Regards and good luck Titus

Anders M,

This is due to the electronic system fail safe. System being activated, when the direction contact pulls in to drive the truck If the system detects a fault it blows the contact out and the truck appears to leap, there may be a short on the wiring or the logic unit may have failed a board component may be failing possibly one of the three thyristors has failed or one of the flywheel or braking diodes has.
The system on this truck is known as the mark v second system,
If you take the lid of the logic unit you will see that the unit comprises of a base board with four other boards plugged into it also several relay assy all these can be removed carefully to be examined for burnt out circuits,
Check the shorting contractor make sure it's not stuck in as this would also cause this problem.

Regards and good luck Titus