Engine is hunting

[mao7w]

Hi started my sceptre this afternoon only to find that the engine is (hunting). what I mean is the engine revs up then cuts, then revs then cuts, but ticks over like a sawing machine, also the rev counter works and revs up then just drops to zero.
I am assuming that it may be electrical. any ideas!!!!!!!!!
Thanks
Graham

[hoppo]

the obvious hunting problem is a rich carb? how about a stuck choke or even a collapsed air filter, but I expect you have looked at all the most obvious ones, allways very herd to diagnose via email, I am thinking what moves when the engine revs up "Distributor" maybe the points are off and when the base plate move they fail? even the little fly lead shorting out, if it turns out not to be electrical after all the similar symtons could be the float valve sticking on a bit of muck starving the fuel flow the when chamber is empty it drops and fills engine revs valve sticks and repeat over and over ....It will turn out to be something simple... but finding it might be a different story..... the rev counter will be fed from the coil so it would be worth checking the wire is sound and attached correctly, It can short on the counter body if plastic cover is faulty or it had been fitted badley (by a previous owner), sorry to be vague .... if you where near skegness i could have a look for you ? best guess rev counter wire or distributor ... pick a start point and go through every thing one by one try not to jump from one part to another untill you are happy the one you are working on is good, all the best hoppo.

[djnippa]

Usually I find the fuel/air mixture is not set correctly (A lean mixture can be a cause).

Have you recently run your petrol tank low?
It starting happening to my car once, and I'd actually dragged through a bit of crap from the petrol tank, and it was slightly blocking the filter and it had also partially clogged the carb.
So it's a domino effect.
You could have an air leak in your carb as well.

[mao7w]

Thanks chaps,
All good suggestions, I will be investigating the problem asap. and of course i will be letting you know the outcome.

[mao7w]

Just to let you know I have sorted my running problem,
It was the distributer, took it out and found that it had excessive play in the shaft, replaced it and all is aok, just need the sun to shine, and I can lay down some miles. (happy days).

[hoppo]

Well done nice to hear of results.... any piccys?