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MG Midget and Sprite Technical - Lumpy tickover

My 1500 starts ok and when i rev it tits sounds great but at tickover its hunting and lumpy. Its been off the road for over a year what should i check first,someone told me the SU dashpots need the oil changed. Is there anything else while i am in there?
Many thanks for perusing my problem. Iain
I Hamilton

Have you changed the fuel? They are really fussy, and, if there is any crystallisation of it because of the time it's been off the road, then, that will block them and make it a bit icky ticking over. What revs is it ticking over at?
rachmacb

Hi, its ticking over about 750/800 rpm.
good point about the fuel. its got half a tank in there, do i have to dump that? at todays prices thats a shame. perhaps i could use it in the lawnmower.
I Hamilton

Yup - the current fuel prices make you want to cry when dumping - but, it should run the lawn mower ok - it not being so fussy ......

Start at the carbs though and follow the system back and see if you can locate any crystallising in it - it might not be, and, it might be just a little bit, which would save you the throwing out or reusing!

Could try it ticking over a bit faster for awhile, and see if that clears it - which would fiddle the carbs a bit anyway. You can always drop them back again and save fuel that way :)
rachmacb

Must say, I have never dumped fuel - well, not intentionally! Might be different in a hotter climate and if the octane rating were much lower to start with. But I really doubt this would be a significant problem in the UK. I might top it up with some fresh though.

As well as filling the dashpot oil, check that the carb pistons drop cleanly with a nice "clunk" indicating that the jets are still properly centred. Also check that the carb and the manifold nuts are all nice and tight - an air leak there would make it hunt as you describe.
Guy Weller

LOL - it was in mine - and I'm not THAT much further south!!! Took ages to locate it, empty it out, clean it all up and refill it - I suspect the previous owner ran it down quite a bit too and picked up dirt, which just went to make it more hassle as she had a problem with the fuel tank reader - not to mention the fuel tank...

My uncle told me to start at looking at the fuel - and he's just down the road from you ;)! I think it just happens when it's been sat awhile with old fuel in and isn't anything to do with the temps.

Several tanks of good petrol and redax (or however you spell it!) seems to have really kept them good too.
rachmacb

Cheers guys i have a lot to act on now, will start at the carbs. will post results. Thanks again.. Iain
I Hamilton

no you dont have to dump fuel Iain

if the old fuel was four or five years old, just maybe.

Fill up with "all new 95 RONs" to top up your tank, that will freshen it enough, then drive it.

Oil the dashpots and check the pistons drop proper like

If it was fine when you parked it it will only be some minor maintenance neded to get it going again oil the linkage pivots and all the carbs' moving external parts

Check the points, gap and condition, check the plug gaps too.

And check the dizzy cap for damp inside too

mine often sounds lumpy if its idling below 8/900

bill sdgpm

Am just waiting for the weather to warm up to start work getting the car running and stopping then MOT!


I Hamilton

Hi again folks, i just pulled the vacum advance hose off and there was no difference in tickover, should there have been?
I Hamilton

This thread was discussed between 18/04/2010 and 01/05/2010

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