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MG Midget and Sprite Technical - Dead Sprite - Don't Send Flowers

My 1964 Mk II 1/2 Sprite is d.o.a. (dead on axles). I was driving along @55mph when the engine quit. All other electricals (lights, horn, starter) work fine. The electric fuel pump spins merrily along. But there is no spark. I have replaced the coil, HT leads, and distributor cap. Still nothing. When the car was warm (when it ran), the engine would run rough and we would have trouble maintaining cruising speed. This last time it was running fine, then it just quit (it was in the cool of the evening). Any ideas would be appreciated.
Mark W.

have you tried replacing the points and condenser, many problems with condensers in the last several years, so buy several....(all made in china by 7 year old girls).... maybe wire loose on back of tach.(that maybe mechanical...not sure)...pull the cap off dist. and watch that the dist. is turning (rotor bug) when starter is activated.....look for a short or bad spot in the wiring.

is there a grounding strap from the engine to chassis..if so is it clean


if none of that ...try running a jumper wire from pos. side of coil to pos. side of battery...BUT disconnect wire from loom to pos. lead on coil and see if you get a spark at the plug...while activating starter.

Are there any broken or missing pieces inside the dist.


BTW...Before you do any of the abbove...is this a postive ground car????

if so,,,,dont do any of the above and consult someone that knows more then I do about positve ground cars.



just a last remote thought maybe the machanical regulator need adjusting


prop
Prop

Check the rotor. Is the distributor turning? Replace condensor? Defective points? Electricity at the coil? Ignition switch failure? Good luck.
Mike G

Hey Prop, amazing we were both suggesting the same thing at the same time.
Mike G

yeah no kidding !!!

I guess its true...god like minds think alike lol.


prop
Prop

Ignition switch.....?

Mark
Mark Boldry

Suddenly dying like that, I'd look for a wiring break or a dead rotor arm. The latter can look perfectly good, but fit another and away you go. New ones aren't immune from sudden failure either.

Paul Walbran

Rotor arm caught me out several times with no warning, esp if you're running >30 thou plug gap...

A
Anthony

Another vote for the rotor arm
Dave O'Neill 2

Another rotor arm vote!
Rich Amos (1330cc Blaze Red '72)

I'd check the pixies havnt gone on strike in the wires - they get bored carrying aroung the electrons all day and need a break.
Dave Price

"The electric fuel pump spins merrily along."

The std pump (at least on my '73) should cut out when it has filled the float bowls. If it keeps ticking maybe fuels not getting through ?

(Irrelevant if the "no spark" is your issue but thought I;d mention it anyway!)
Dean Smith ('73 RWA)

I'll be unconventional and agree with Prop rather than rotor arm

Intermittent bad running before the fact m'lud would infer a beginning to go "duff" status, often condenser based rather than the normal "rotor suddenly shorts to earth" scenario

But a defective ignition swich is also quite high up the list of quick easy tests I'd do at the roadside with the car

With ignition on find out if there's electric at the coil, both sides. If so then move into the dizzy to check the wire in and then the points.

Check there for electics too and see if that changes with the engine cranking
Bill

On re-reading the original sequence, I see I missed the comment about it being rough when warm, and had just focused on suddenly dying. I agree with Bill that the condensor is a prime candidate for "rough when warm", especially given that the only other common cause of this has been replaced (the coil).

Also about potential dodgy leads inside the distributor.

The points can suddenly cease functioning to when they have worn away so much that they lose all gap. This failure too is usually preceded by rough running - however it is usually also hard to start when cold.

The simplest check sequence is to check for a spark at the points. If there is one there, you have primary circuit continuity.

Then check for a spark at the coil. (None by the sound of it)

That would then focus you to what's in between - probably inside the distributor. Check further for:

Very small points spark - dirty/worn points, ignition switch dodgy and anything else which will reduce the primary current without killing it.

Larger than normal points spark - condensor

Normal points spark - rotor arm (or cap or leads or coil - but you've replaced them already.)

The internal distributor electrical components - points, condensor, rotor, low tension lead - are all cheap, get a set and replace them one at a time to see what does the trick (for future reference)
Paul Walbran

Oops, meant to add that if you have spark out of the coil, but not at the plug leads, then it points to rotor arm or cap (and the latter has already been replaced)
Paul Walbran

well if that dosnt help our new friend, Im curious as to what will....looking forward as to what the problem was.

gezz how many times have we all been in this spot before....its funny how we all have our own "Instinct" reoutines that we automatically go for in a given situation....at times I even do it in my sleep....

is that sad that your midget even breaks down while dreaming about driving your midget while sleeping

prop
Prop

Thanks guys! It was the rotor arm after all! After putting the new one on, the buggy fired right up - I was amazed! With the new coil, wires, cap, etc., the Sprite runs a bit smoother. I think my next step will be to install an electronic ignition system. I sourced another rotor to put in my tool bag (just in case). I'm going to also check the gap on my spark plugs. Best Regards, Mark
Mark W.

rotor arm....Ha!!!....My gut was saying condenser.

glad you got her up and running.....hope we see you around here for time to time.

good luck.....remember iin 2 more weeks begins "National british car week" So make sure you drive your car every day for that week no matter what.

prop
Prop

great news that it's ONLY the rotor arm

ONLY? Cor!
Bill

Hey Bill,

ONLY, for this week anyway....LOL.

prop
Prop

This thread was discussed between 16/05/2008 and 17/05/2008

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