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MG MGA - Ignition problem

Sorry I'm coming straight here instead of the archive. I'm blindingly frustrated and working from my phone.

The car ran last week. Today the there is no spark.

What is the process for checking the system out.

Everything in the system (except the plugs which are new) is older but with few miles on it. Something like 7,000 miles.

I've checked all the connections.

I have a flamethrower ignition coil
Petronix electronic ignition
The distributor was rebuilt 7,000 miles ago
Cobalt ignition wires

Thanks in advance
Tysen McCarthy

Easy to wreck the pertronix. Can you put it back to points and see if the car runs? I expect it will be much easier to troubleshoot in that format.
J MacDonald

Unfortunately no, I don't have the original point system to reinstall. Is there an understandable way to test individual parts of the system with an electtric tester.

Tysen McCarthy

If all the connections are correct and there is power to your Pertronix ignition (there should be a constant 12v feed from the ignition switch) and it doesnt work, then the Ignitor has probably failed.

You will have to get Pertronix to check it for you or someone who understands the electronics inside it.

I had two Pertronix electronic distributors fail within a few months of each other and it turned out to be caused by my faulty voltage regulator that was putting out around 20 volts.
These electronic systems are really sensitive to over voltage and anything over about 14 volts can cause damage.

Unfortunately, it wasnt until the 2nd unit failed that began to suspect it may be a problem with my car and not with the Ignitors.

Since I fixed the voltage regulator problem a few years ago I have had no more problems.

So I would check your voltage at the coil before you fit a new one.

Colyn


Colyn Firth

Ok, here's what I'm understanding so far.

1) With key turned confirm 12 volts from white hot wire to ignition coil

2)......I presume there is a way to confirm that there is voltage running from the ignition coil to the distributor? Any feed back on that?

3) if there is voltage to the coil and then two the distributor, I presume that is confirmation the pertronix is shot.

Sound righ?
Tysen McCarthy

Here's a thought. Can't I just hook up a timing light? if it runs the coil works, if not the coil doesn't work.....
Tysen McCarthy

If you use your timing light and put the clamp on the king lead from the coil, the light will flash if the coil is working.

Move the clamp to one of the plug leads (wires), if the light doesn't flash, it's the rotor arm.
Dave O'Neill 2

Carry a spare Ptonic is good advice, as they re near impossible to diagnose when car is no go.
J MacDonald

Why not just pull a plug and look for spark?
S

Or maybe try starting again then pull four plugs and check for wet. Good idea to try and see plug spark, but that will of course void the Pratonic warranttee or fry it if it not now. Always a good idea to remember to replace rotor. Also if battery low it may not be reaching minimum threshold voltage to fire the ptonivc.
J MacDonald

This is specifically for the E Type but will apply just fine to the MGA too.
A Bowie

And here's the link:

http://www.projectetype.com/index.php/the-blog/270-nospark.html
A Bowie

Thank you for the feed back.

There are a couple of notes.

The reason I want to test beyond seeing if the spark plug lights is because I want to see if I need to replace a $40 coil or a $144 Pertronix ignition system.

I am curious why testing the plugs by grounding them at the mouth of the plug opening would fry the ignition system? Wouldn't that just replicate the flow of electricity that currently exist?

And I have indeed tested the plugs for spark.

Tysen
Tysen McCarthy

I think the ignition system can be damaged if the spark has nowhere to go Tysen, particularly if you have the massively powerful Flamethrower coil.

I should be ok if you are sure the spark plug is well grounded on something before you test it. I use an old jump lead clamp to hold the sparkplug solidly onto a cylinder head bolt.

Colyn
Colyn Firth

Tysen

Equivalent to the Pertronix and significantly cheaper, is the Accuspark unit that I use. For the same money you could buy a brand new distributor with the unit fitted

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xaccuspark+mga.TRS0&_nkw=accuspark+mga&_sacat=0

Dominic
Dominic Clancy

Tysen, my comment about voiding the protonix warrant was tongue in cheek, as everything out of the complete ordinary seems to void warrants these days. Don't tell them about that test, it is what I meant.

I have found these things seem to fail in a mode where they still are delivering spark you can pick up with a timing light or the plug out of block test, or maybe some electronic wizardry, but it is a very weak spark so weak it will not likely start a car without much bother, but then appears to be working once (if) you can get it started, but really is still a weak spark.

J MacDonald

Sorry I missed the joke J. Probably a sign of how frustrated I am.

Dominic, unfortunately they don't sell Accuspark in the US. I'm sure I could buy it and have it shipped but I'm stuck in the garage until I get it.

Off to start testing.
Tysen McCarthy

"And I have indeed tested the plugs for spark."

What was the result?
Dave O'Neill 2

"Put a 12v test light between the negative coil terminal and the black/white wire to the distributor. Crank the engine. The light should flash off and on as the points open and close. This should work with electronic ignition modules as well because what you are testing is the circuit through the points (mechanical or electronic) to earth."

This should tell you whether your Pertronix works or not.
A Bowie

Result of plug test was that there is no spark.
Tysen McCarthy

Tysen, but when you tested earlier it did show spark, yes? Probably it went from the low spark failure mode to the no-spark failure mode rapidly. Those Protinix things will give you an ulcer, won't they? Using a 1.5 or 3 ohm (primary) coil with ballast or no?

I once accompanied a pal on a long trek when the car would not start after stopping for fuel. Pal suspected the Pton device and had a points plate at the ready in the toolbox, all set up and gapped with a tested capacitor and a simple wiring diagram. Took all of 5 minutes to unwrap wires and switch things around. Fired right up with points. That was my first experience with the low energy failure mode of these things.
J MacDonald

"J MacDonald, Ontario, Canada

Tysen, but when you tested earlier it did show spark, yes? Probably it went from the low spark failure mode to the no-spark failure mode rapidly. Those Protinix things will give you an ulcer, won't they? Using a 1.5 or 3 ohm (primary) coil with ballast or no?"

J, when I tested the plugs earlier it did not show a spark and the plugs were wet.

Its a 3 ohm coil.

I spent the day testing.

I checked the voltage to the coil. It was 12.6 volts

I tested the coil. I ran an ohm test through the coil and it came up steadily at 3 ohms. I took the High Tension line from the coil and tested for a spark from the coil against the block. Good spark was found.

I put the timing light on number 1 spark plug wire to test power to the plugs and as my good natured wife turned the car over it immediately started.

WTF!

These cars are a mystery. I am going to throw a plate with a standard condenser and points.
Tysen McCarthy

Sounds like not enough choke on start up! then you went to deep in trouble shooting.

How do I know? done it! lol!

Oh ya... get one of those test lights that plug into the spark plug cable and the plug...life will get easier.

leave the pertronix...I've rune one for over 15 years with no issues.

http://www.toolpan.com/Lisle-20610--Inline-Spark-Tester_p_2984.html?gdffi=f5e6a8f688944f56808efdd781510f49&gdfms=32723A107E2241F1B3F2BCA606DA77A7
S

Don't want to worry you Tysen but when ( both of ) my Pertronix failed, the first symptom was that there was no spark.
Then after a hours pottering about the engine fired up ok and I drove the car home with no problems.

But the next morning the engine wouldn't run and nothing I tried would make it go.

I hope this doesn't happen to yours.

Colyn
Colyn Firth

Colyn,

That this is an early indication of imminent failure is exactly my concern!

I'm going to nose around to see if I save the original points and condenser plate. That was 10 years ago so I have no idea if I did.

SD, if anything I flooded it and it didn't go.

I'm still fairly positive that there was no spark. The plugs came out wet.

I'll keep the next few rides close to home.
Tysen McCarthy

I am concerned.

Last year I changed to Pertronix getting fed up with condenser etc issues, hearing rave reviews here but now there seem to be as many problems as with standard distributors. At least I could fix points and conds by carrying low cost parts, but I do carry a complete known working traditional distributor in space by master cylinder Colyn style. I haven't had any Pert issues yet.

Paul
Paul Dean

You can stop worrying Paul,
it was fault in my voltage regulators output that was pumping over 20v into my battery.
Amazingly, this had been the situation for a year or more and so the Pertronix had withstood this for a long time before it failed.

The replacement unit I fitted also failed after about the same time, it's a pity I never checked the charging voltage earlier.

If you want to check the charging voltage make sure you measure it throughout the Rev range as mine was reading 14v at 1500 rpm but went up to 20v at 4000 rpm.

I am still using the electronic ignition and I am sure that it will be reliable long term.

I used to carry a spare std points distributor and coil in case of failure but the one time i needed it, I discovered that the offset dog on the points distributor was about 40 degrees different from the Pertronix and so it wouldn't run without me first finding tdc on the cyl 1 firing stroke and completely re-timing the engine.
So it wasn't really much use as a roadside fix.

Colyn
Colyn Firth

Well Tyson, you have acknowledged the answer: "WTF". Just remember next time "Wife Tries First" and it will start.
Graeme Williams

Wife Tried First! Indeed.

Paul, I wouldn't worry. I went back through some of my notes and my Pertronix is 10 years old and I haven't had a problem up until now. That works out to a $14.00/year investment.
Tysen McCarthy

Call me a Luddite but after 2 strandings in 6 months courtesy of failed Pertronix units I have gone back to points on my MGA and my E Types. They just work...
A Bowie

Hi Guys.

I'm pretty sure I have just fried my 123 electronic distributor - not cheap. Now seriously considering a points replacement with vacuum. Any suggestions as to where best to purchase a new one ( for 1600 Mk2).

Moss Europe D45 are on back order - and expensive -and I have a place on the track at Goodwood in 3 weeks time.

Advice would be appreciated.


John
John Follett

John

Bob West supplied me with an unmarked Chinese version of the D45 about 8 years ago. It's been brilliant and only cost about £40 back then.

Steve
Steve Gyles

You can buy a new one here, with or without electronics inside

And MUCH cheaper then the 123

http://accuspark.co.uk/distributors.html
Dominic Clancy

Thanks guys.

However all started ok this morning! I guess this means I must have another problem.

The background is: Took the A out for a drive yesterday, everything great for around 10 miles and going like a train, engine then died on me. Backfired as it did.

Disconnected fuel hose to rear carb, all fine.No apparent problem with fuel pump. All other electrics working. Turned over ok but would not fire. Waited 5 /10 mins and started ok.

Another 5 miles and engine misfiring, but only briefly.

2 more miles and engine died completely. Fuel flow/pump still ok.( as above)

Tow truck home!!!

I thought it may be sticking grosch needles, but seem ok. Fuel level in float chambers good too.

2 gallons fuel in tank so I hadn't run out.

Any thoughts anyone?

John
John Follett

Rotor arm shorting through when hot.

Regards
Colin
Colin Manley

What color is the rotor and is it riveted together? If it's black and riveted get one of the good red rotors. Just went through this with a club member's AH3000.
Ahrendt

When a rotor fails and shorts to ground, it is usually instant, no procrastination. One second running fine, the next second dead. If it coughed and sputtered for couple of miles, then most likely not the rotor.

There is nothing magic about color of the rotor. The last failed rotor I replaced was red. The position of the rivet too close to the center shaft is the problem. Rivet farther out is okay, and bonded contact with no rivet is good.

If you are still running the electronic ignition, that would be first suspect. Otherwise a coil can fail when hot and recover when it cools off. Very rarely a condenser can do the same, but more often a condenser only gets worse, and usually in very short time frame.

Loose base clamp on the distributor can cause spark failure for loss of ground connection.
barneymg

Runs then stops when hot suggests coil failure to me.
A Bowie

John

I had exactly your symptoms a couple of years back and it was the condenser in a brand new Moss distributor.
When I got back to Moss they admitted they have 2 qualities of condensers. The better one costs a few pounds more but works vastly better. Why they carried on selling cheap one I can't think. It has same part number with an 'x' on end.
I cut failed condenser in half and it was not surprising it failed as it isn't soldered inside but relies on pressure between can and actual condenser to maintain electrical contact. Clearly as it heated up it lost contact but got it back as it cooled.
I was in remote west of Scotland when it happened and in the end recovered home by RAC. Bizarrely I had a spare condenser but didn't believe it could be anything in distributor as it had only done 150 miles and wrongly suspected coil.
I will get back with pictures if I can find them. By the way all this was on this site at time.

Paul
Paul Dean

Thanks to all.

Barney - I do have electronic ignition. Are you suggesting it may be the distributor and not solely the rotor arm? I replaced the distributor about 3 weeks ago.

I think I will go belts and braces - rotor arm and coil.

John
John Follett

John
If your misfire was a progressive one where the engine went onto 3 cylinders firing, then 2, then 1 and then stopped,
the problem could still be down to low fuel flow.

The fuel flows to the rear float chamber first and then to the front one.
So the front carb runs out of fuel first if there is a fuel flow problem.

So check the front float chamber first if this happens again as the rear chamber could be full whilst the front is empty.

To check the fuel flow, put the end of the carb flexy fuel pipe into a container and switch on the ignition, you should get a flow of at least one pint per minute.

Cheers
Colyn
Colyn Firth

I had everything new in my ignition system and the car failed to fire after about a 10 mile drive and had to have the car towed back home. Fuel was checked first as it is easy as you have gas flow or you don't. Next I checked spark at the plugs. I had no spark. Next I pulled the coil wire and put it next to ground. Turned engine over and had spark. This meant that the problem was in the distributor.The problem was the rotor. Since pulling the rotor was easy, I changed it out with the old rotor and tried again. It fired up. I ordered the new rotor from Advanced Distributor
JEFF BECKER

This thread was discussed between 27/04/2017 and 18/05/2017

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