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MG Midget and Sprite Technical - engine misfired, now it's dead

Hi,
I have just changed the alternator and fitted the needle Peter Burgess recomended when up on his rolling road last.
I wanted to check the mixture this morning, so I warmed the car up - it ran fine. I ran out of time so switched off and went back to it this afternoon.
This afternoon, I started her up. She started first flick of the key. I thought I would drive her to warm her up this afternoon so reversed her out of the garage and she started to misfire. I fiddled with the choke, pushing it in and pulling out to see if that made any difference, no change. The misfiring got worse and reving the engine didn't help. I managed to keep the engine going for a minute or so but then it died. It will not fire now.
While it was misfiring the tacho needle recorded the revs , it didn't jump up and down suggesting it is not ignition.

I have not checked much yet, just the fuel and there is fuel pressure.

It is a 1275 with single hif44, 123 tune dizzy and an imobiliser where I have to wave a black plastic thing on the key ring under the ignition barrel until the light on the dash goes out. The light lights when it should and goes out suggesting that this is working correctly.
It ran well in the week with no hint of anything going wrong.

I am going to check for a spark shortly and measure the fuel flow to ensure that is ok.

Anyone have any thoughts?

Thanks
Dave
Dave Brown

Sounds daft but make sure the needle hasn't fallen out.

Peter
Peter Burgess Tuning

Hi Peter,
The needle is firmly attached but good point, Peter, thanks.
I removed each plug and each one was black and wet.
I checked each plug lead for a spark - keeping in mind what happened to Willy Revit, hope you get better from your latest incident soon - and the 123 was delivering a really big fat spark to No 1.
No 2, with another plug, and hardly a flicker and right up inside the plug, not at the electrode. same thing for No 3. No 4 was good.
So, 2 plugs gone bad.
Fitted a couple of old plugs and she started first time. Trouble now is that I have 2 bp6es and two bp7es. A trip to the motor factors in the morning...

I think I will switch back to bp6es plugs.

Dave
Dave Brown

Hi,


Never assume the immobiliser is working correctly just because it's red light goes out1



What circuits is it tapped into?



Live at the coil?
SR Smith 1

"Sounds daft but make sure the needle hasn't fallen out."
It can happen!

One time (back in the days when I was a young fella) I was driving my trusty 3.8 Mk2 Jag home form work when suddenly it lost most of its power. Took a big run-up and a lot of coaxing to get up a bit of a hill.

Got home and quickly found the problem - one of the needles had dropped out of the piston and was blocking off the jet. What was really interesting was that the power available was much more than halved. The 3.8 had twice the poser of the 2.4 variety, and having owned the smaller engined version I can say that half a 3.8 was well down on that. An illustration of puming losses I presume.

The other time I found it was quite recently - a new customer with a TF1250 couldn't get it to run on all four, only the front 2. Thinking back to the above experience I removed the rear dashpot on the off-chance that lightning can strike twice ... and indeed the needle was left behind in the jet.
Paul Walbran

Sounds like your fouled, im glad it fired.back up on the old plugs

What brand of plugs?


Prop
Prop and the Blackhole Midget

Try a new condenser.

Just had a similar problem with a friend's frog eye and that's what it turned out to be. Driven tacho though, so no point in looking for tacho fluctuations on that one.

Peter
Peter Blockley

Make sure thees no water in the gas. A bottle of dry as is cheap and will help rule out bad gas. I know this is a little off your topic...but when ever an MG I own starts to run like crap unless I recently did something to make a change...its usually water in the tank.

Goodluck!
Steven Devine

Sorry guys

But you all are a little to cabin crazed,

Dave brown found the problem... it was fouled plugs

Prop
Prop and the Blackhole Midget

Hi
It was the plugs.
Thanks for all the responses.
There is no condesnser - it has a 123 tune electronic dizzy. The gas/petrol was fine in the morning.
I am using NGK plugs. They only have a couple of hundred miles on them. Going back to bp6es (the fowled ones are bp7es).
Dave Brown

Champion
mog

This thread was discussed between 27/06/2015 and 28/06/2015

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