MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Well, it's not the ignition switch.......

Hi folks,
I've been dealing with an intermittent ignition problem for a couple years now. The engine just dies when warm. Usually, after a few minutes, it will start back up, but then die again after a few more miles. I can't make this happen by jiggling or pulling on wires, I'm at somethings mercy. I've replaced the ignition coil, ballast resistor, rotor, cap and plug wires.
My latest attempt was an ignition switch. I just wired it up under the dash as I wasn't about to pull the steering column unless I had to. Ran around a bit this morning and seemedto be great. Dropped dead just as soon as I got on my street. At that time, I hooked up a timing light and got nothing when turning the engine over. No indication the cylinder was firing. I checked the voltage to the coil while the ignition was 'on' and there was a 12 volt reading there. Now, I suspect the electronic ignition module (what's left ?). After a 15 minute wait the car did start. Usually I don't have to wait that long.
Well, anyway, what should I buy ? Every replacement I see has only two wires, while my existing set-up has three. How do I find my Lucas distributor number ?
I looked at these on ebay.....Thanks for the suggestions. It would be nice to be able to drive again.


http://www.ebay.com/itm/pertronix-Ignitor-for-Austin-MG-Triumph-4cyl-w-45DM4-47DM4-Lucas-Distributor-/170916283449?fits=Make%3AMG%7CModel%3Amidget&epid=1017873577&hash=item27cb678439:m:miF3dXgIPE6_yLH2hvJkQfw&vxp=mtr#vi-ilComp

http://www.ebay.com/itm/MG-MIDGET-MGB-TRIUMPH-SPITFIRE-TR7-PETRONIX-ELECTRONIC-IGNITION-KIT-OPUS-75-80-/380893864340?epid=1529941058&hash=item58af0b2194:g:T7YAAOxyHIlTXZCS&vxp=mtr

http://www.ebay.com/itm/Pertronix-LU-143-43-44-45D-DIST-RED-4CYL-/161517223511?fits=Make%3AMG%7CModel%3AMidget&epid=202870316&hash=item259b2d3e57:g:NbEAAOSwZkJUSuoB&vxp=mtr#vi-ilComp
Paul W 1976 1500

What ignition system do you have

DO NOT GET ANYTHING WITH PerTRONIX

I like the idea and concept of the perteonix and at one time, several decades back it was a good chip, but now there more of a road side emergancy repair...there just so badly made

Id look at (simion bbc ??) There a great product across the pond and use the same concept

Frankly...id look at a good quality points and condenser set

Id probably look at the guts of the dissy 1st and make sure you dont have a poor ground wire and the condition of your dissy guts, as well as ignition system

Maybe wrap the wiring harness where it passes thur metal holes for chaffing causing a double ground

Are you sure its eletrical and not fuel related like a failing fuel pump

Prop
1 Paper

When it died today, I hooked up that timing light and got nothing. Anytime I have pulled the hose off the fuel pump, it always started filling a jar.
I have a factory electronic module now.
Paul W 1976 1500

At the risk of sounding like a broken record...what type of rotor arm did you use, was a it a genuine 'red' one?
Jeremy MkIII

I once had a problem with very similar heat related symptoms. It turned out that the wire between the coil and my electronic ignition module was fractured internally but the insulation was intact. As the engine bay heated up the insulation on the wire would soften, allowing the wire to sag under its own weight and break the internal wire connection. When it cooled down again the insulation stiffened and contracted to allow the inner wires to make contact again.

But the clue to look for is an intense flickering of the rev counter needle as the fault is occurring. This is a sure sign of a low tension fault. If the needle just drops smoothly to zero as the engine fails it could well be a fuel fault rather than electrical, unless it is on the HT side of the ignition circuit. (e.g the rotor arm or HT leads)
GuyW

I did, at one point switch to a red rotor arm. The problem continued though, and that is not the rotor I currently have installed.
I have twisted and pulled on the ignition wires and I can't make the engine quit. When it quits, it quits. The tach just drops right to zero, no flickering.
Paul W 1976 1500

Could it be fuel vaporising in the delivery pipe between pump and carb? - where it runs across below the battery shelf behind the engine it is prone to excess heat on the 1500.

The only thing is I would expect it to stutter for a moment or two before quitting, rather than just stopping instantly.
GuyW

Once had a similar situation and it was a bad fuse box.
Trevor Jessie

I insulated that fuel line between the fuel pump and carb last year, or possibly the year before. Just in case. It used to be, when the problem first began a couple years ago, it had to be REALLY hot outside and hot under the hood. Not so much anymore...Drive for 15 minutes or so (it wasn't that hot out today for example) and it will occur.
I pulled the fuse box out a couple of weeks ago and made sure all the connections and fuses were crisp.
Paul W 1976 1500

Maybe heat is a red herring then?
How about a blocked filler cap vent? 15 mins drive time is about right for that.

Sorry if that has already been discounted.
GuyW

Another good guess Guy. I drilled a little hole in the filler cap last year just in case that was happening.
Paul W 1976 1500

Paul, the distributor number is on the side of the distributor. I will venture a guess it is a 45DE4 and number 41646D will be there somewhere.

I have a complete setup here of distributor and electronic control module you can have. If it works, great if not, nothing lost.

My car was converted to a point system. No electronic stuff any more.

Email me your address and I will get that out ASAP to you unless you want to pick it up?

Clare
Clare Ravenwood

Hi Clare,
That's a very generous offer, thank you so much. I just may take you up on that. I'm running out of options at this point. I would probably come over there to pick it up from you. It sure is nice to have that option. Thank you sincerely. I have your email address, so I'll let you know if I need to go that route.
Why did you swap out your ignition and go to points ?
Paul W 1976 1500

When my car came back from having the engine rebuilt, the fellow said he swapped a point distributor in place of the electronic one. Said it was easier to trouble shoot and less likely to leave me stranded. Car starts at the turn of the key if it has been running a while. Sometimes it takes time to get the fuel pumping if it has sat for some time.

Did I send you the BL booklet on trouble shooting electronic ignitions?

Clare
Clare Ravenwood

I suspect the ignition coil. I know you have replaced it already but new ones are notoriously badly made. I once bought one from that company with a 4 letter word and it overheated straight out of the box. I changed back to the original and got my money back. So much for wanting a nice new thingy under my bonnet.

Is the coil on the 1500 mounted the same as the 1275, at a slight downward angle with the HT lead at the lowest point. Coils are filled with an oil like substance to distribute heat and they are filled through the HT connection and sealed. On the modern ones it is sealed with what looks like an ordinary self tapping screw. When mounted with the HT lead at the lowest point it promotes leakiness. Whatever oil they use it doesn't always leave a trace or it leaks so slowly it evaporates so you can't see it has leaked. Once the oil gets low the coil starts to overheat, the less oil the quicker it overheats.

If you shake an old coil and you hear liquid sloshing about it has leaked. If you can't hear anything it's either full or completely empty.

Rob

MG Moneypit

Is it a mechanical fuel pump on the 1500? Could that give the problems you describe Paul?
Jeremy MkIII

Do you have photos of your distributor both externally and inside the cap that you can post?
Daniel

Yes Clare, you did send me that book. I had forgotten that as I was not chasing this problem at that time. That'll give me some good info.
The coil is mounted as described Rob. I could certainly try another one as they are very inexpensive. It does get as hot as a dawg, but I'm sure that's somewhat normal.
I had suspected the fuel pump before, but anytime I pull the line and turn the engine over, it starts to fill a jar. The issue is the lack of spark when the engine does die.
I'll get a picture or two and put them in here. Here are some photos.....whoops....One more down.....I'm having a hard time with picture uploading...
Paul W 1976 1500

Coil here.....


Paul W 1976 1500

Distributor....


Paul W 1976 1500

Not letting me upload more pix.....I can't get two pictures in one thread either.....I'll check back and see if it's just a delay in the boards.....
Paul W 1976 1500

Inside dist.....


Paul W 1976 1500

Sometimes these links will post and sometimes they won't.....More.....


Paul W 1976 1500

If the tach drops to zero as engine dies then there is probably an open circuit somewhere on the primary side of the ignition. Do both sides of the coil primary have 12v when it dies? If so, there's an open circuit between there and ground in the distributor, maybe the sensor (I'm assuming your electronic ignition is a magnetic type sensor which switches on and off). If you had a spare 25D distributor you could, of course, verify if it was a sensor fault.
Bill
W Bretherton

Next time it fails, connect an ohmmeter between LT connection at Dist and ground and push car so rotor arm turns to see if resistance goes high and low as sensor is excited. If no change on meter you have your answer.
W Bretherton

It looks like you have the Lucas 45DE4 (Opus)electronic distributor which was never great and which most people replaced. At one time, and possibly still, you could get a Crane electronic conversion kit for it. It's possible you already have such a conversion kit fitted.

I do have a 45DE4 unit which I photographed for my book but don't think it was a unit ever used in UK Midgets. Certainly the one I have in my garage is the only one I've ever seen.

You might want to consider swapping the distributor for an ordinary Lucas 45 series body for the Midget and then decide if you want to run it with standard contact breaker points or go with an electronic conversion.

I suppose I ought to say 'there are books with this stuff in'. Also the original Lucas ignition system booklets have a lot of detail but you might have a job finding one.




Daniel

EDIT. In which case I should have said "voltmeter". With the ignition on I'd expect the voltage on the distributor side of the coil to vary high and low as the dist. rotates (as with points).
W Bretherton

Thanks for the suggestions guys.
I'll run through them this week.
Paul
Paul W 1976 1500

Good luck, Paul.

If you like, I will be in Niagara-on-the-Lake first weekend in July and in Fort Erie in August. Depending on things, I might possibly have the Midget with me but probably not as my insurance company does not like the vehicle to be left unattended.

The BL manual I copied for you will have lots of info as you can see.

Hopefully it is something simple and I have to check, but I think my ignition coil points toward the rear of the car. Funny how you see something and can't recall it if your life depended on it.

Clare
Clare Ravenwood

Hi Clare,

I sent you an email.....

Paul
Paul W 1976 1500

This morning I swapped out the ignition coin for a new one, and the ballast resistor for a new one. Within minutes of running, the engine started sputtering and choking. I felt the new ballast resistor and it was pretty hot. After a few minutes I started it up again, ran fine for a minute and started sputtering again. I put the old ballast resistor back in and it started up and ran fine.
I did a little driving, staying close to the house. Drove around for about 15 minutes, it dropped dead. The first couple of times it does this, it re-starts within a few minutes, After that, it takes some time.
So, after the third time it died, I knew I had a while. The amplifier module on the distributor was VERY warm, as was the ballast resistor and coil. The coil was still seeing 6.6 volts, but there was no spark. I walked home and got a "freeze-pack". Went back and put it on the amplifier module for a minute, it started right up. I guess that's what I need.....
Paul W 1976 1500

Hi Paul. Have 2 here you can have. e
Email me for details etc. You like to meet at Fort George about 7 pm on Friday then we can scoot over to the town for a brewski at the Olde Angel Inn? We can have a cold one if you like?

Clare
Clare Ravenwood

Hi Clare,
Great.....sent you an email....
Paul
Paul W 1976 1500

Pual,

To me it sounds like a classic double ground issue

If thate the case... that means an ignition wire is lost its insulation and is making contact with the metal ground somewhere or you have put a self taper screw/revit thur the wiring harness or rhe ignition harness wire has gotten pinched and creating alot of resistance

I know we talked about that several times above and each time it was ruled out... but ive seen this show before and i really think this is the issue

Try checking the temp of your choke cable also the next time your coil and ballest resistor get really hot... if it is, that can indicate some bad grounds

Also ... try pulling the dissy and clean the contact area bettewn the engine block and where the dissy makes contact ro the block

While the dissy is out, twke it apart for a good cleaning and inspection under bright light and look for any wear

Have the thermo block looked at that black sealed block on the wire kf the ignition, they cant be repaired but maybe age has had its effect... not sure how to test that

Last note... in the mean time, when your done for the day each time, unhook your battery so its not hooked up over night incase it the bad wire catches fire

Keep a ABC fire extinguisher in your car at all times incase of electricsl fire

And last remove the ignition wires from your tach

gauge and hook it back togather without the tach gauge until this is resloved

Tach gauges make for very expensive inline fuses which is what your tach gauge is if this is an elecrical igition wire wire shortimg out

Sorry to keep going back to this... it just feels like it when you post your info
1 Paper

Thanks Prop.....I'll grab a few cables, like the choke, when this occurs again. I can't imagine that I would have damaged the harness. I haven't put any screws through anything, or stuff like that. I have nice grommets in the firewall and the harness is well wrapped. Sounding like a grounding wire issue, yes it does, but I'll be dipped if I can find it......
Paul W 1976 1500

One thing you can count on...when you find it it will be really stupid

Always is
1 Paper

This thread was discussed between 23/06/2017 and 05/07/2017

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.