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MG Midget and Sprite General - Car stalls when slowing down....

I would welcome thoughts on what my problem might be. The car (61 Sprite - pretty orginal throughout) is stalling when I slow down to close to 0mph eg going round corners, going up to traffic lights etc. It is tricky to start up straight away but starts fine when left for 30 seconds or so. Seems to idle okay, it is just when the car is slowing down that it stalls. Any guidance welcome. Thanks.

Tim
TJ Prime

How is your oil pressure when this is happening in the corners/lights?
On my 1500 this used to happen when my oil got very low (it leaked like a sieve). The oil would surge forwards under breaking and go away from the pickup. 0 oil pressure and the bearings started to grab the crank and con rods stalling the engine. The wear on these components then made the engine hard to crank over before oil pressure had built up from a recent attempt/run.

Hope it's not that!
RoadWarrior

Hi Tim

Like most things this can be sorted once understood.

The term "stalling" is a very descriptive expression and refers to the car stopping when the engine dies as the car is moving.

Is that the case that as you slowdown the engine dies and causes the car to stop?
Does it happen as a result of you putting the clutch in?
Alternatively do you mean the engine simply dies hen you stop?

It is important to answer these points as the problem you are describing can be caused by 2 things. Either a poor clutch/ thrust bearings. Or more than likely the engine is not tuned up correctly, probably carburettor settings.
Robert (Bob) Midget Turbo

Oil pressure is fine. No problem there. It is as the car slows right down at very low speed that the engine dies. As you slow down the red ignition light flickers and invariably I am putting the clutch in at this time to try to keep the car from stalling. I am inclined to think that it relates to tuning rather than a clutch problem. I did note this afternoon that the carburettor pots were a bit low on oil - could this be part of the problem perhaps?


Tim
TJ Prime

Hi,
You say that it idles OK, but at what speed does it idle? It sounds as if increasing the tickover speed a little may help.

The other question I would have is does it burn much oil?
Is it smoking a bit on the over-run as you slow down?
Guy

OK Tim

What revs do you think you are running at when the car stalls?

To run a car at very low RPM requires that the carb set up is absolutely spot on.
Robert (Bob) Midget Turbo

And the reason I was asking about possible smoking and oil burning is that if the engine is drawing in oil on the over-run, this will lower the octane rating of the fuel. If it is already set to a lowish tick-over level, this lowering of the octane can just be the last straw and cause stalling.
Guy

Id also check that your not running overly lean, (vacume leaks) the valves arent arent adjusted to tight, you got good exhaust flow..(how old is that muffler), and check the plug gaps, could even be a slightly sticking float needle, check your ignition wiring for loose or croading conditions, check your points on both the dissy AND the SU fuel pump... if its been sitting for awhile, The points can get a little filmy..., fuel and air filters clean ...how old it the fuel, in the past 2 years alot of stories of fuel going bad in a matter of a few months

just a few ideas to keep you busy
Prop

Oddly enough



What Prop says

Er OK

Some of what Prop says

Before doing anything else check your points GAP

Too close together and you may get reasonably easy starting but under duress it may hate idling

Like yours does


But all the other stuff also applies, take up the idle rate to near 1000rpm

Note I'm not suggesting anything to do with the condenser




yet
Bill 1

Rather than take a methodical engineering approach such as Bob suggests, I'll just chuck in the random fact that mine had a very similar problem - sputtering out on rolling up to junctions etc. As far as I can tell it was over-fuelling and flooding, leading to stalls and difficulty re-starting. My cause was too high a pressure from a Facet pump swamping the Weber. Cured by installing a fuel pressure regulator betwixt pump and carb (arguably a more suitable pump would have been a more elegant solution!).

Now your root cause and solution will be different, but perhaps there is a carb problem producing similar issues? Best to work it through and diagnose properly as suggested above, but something to consider.
Jordan Gibson

Thanks for all these helpful comments. Next Saturday is the next time I'll be able to check things out - I'll let folk know what my findings are. Cheers. Tim
TJ Prime

When the throttle is closed and ther mixture is very diluted, the vacuum advance works to fire the spark earlier to give this poor mixture time to burn. If the vacuum diaphram is punctured two things happen; the necessary advance doesn't happen and the car could stall and just before the throttle closes more air gets sucked into the inlet manifold through the diphram. Check the vacuum advance.
Allan Reeling

On a different bent, perhaps you should find a lovely assistant to help you check for crankshaft end-play when you push the clutch.
David "out of the box" Lieb
David Lieb

Did a few things. 1. Checked the points gap 2. topped up the oil in the dashpots (they were a bit low) 3. slightly adjusted the throttle adjusting screws. Took it for a run and the problem seems to have been sorted. Not sure which of the above was the cure but fingers crossed..... Thanks everyone. Tim
TJ Prime

well done

Time also for a full and proper service (maybe?)
Nigel Atkins

This thread was discussed between 27/03/2011 and 02/04/2011

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