Passed MOT But!!!

[RobSun]

CWL78Y passed its MOT this afternoon with no advisories so yippee.

But its still got hot start problems just as my previous post. Its behaved itself since fitting the new coil and on the way to and during the test. Due to the roads around where I live being resurfaced the cheap way with chippings that I got caught out with on the way out I came home the long way to avoid as much as poss. Well that's my excuse for a long drive and I am sticking to it. This route took me by the guy who fitted the electronic ign. and who's done other work for me so I pooped in.

He gave my fitting and wiring a check over and said it was all done ok. I asked him why I only had one old supply to the coil and this was 12v. He checked it out and said that there was no ballast on it so the ballast wire had broken down, been removed or it never had one in the first place. He went on to check the solenoid and said it was an early one fitted and there was no hot start feed from it and looked like it had never had one. There was no loose wire or any sign of one ever going into the wiring loom from it. So that answered all the questions I had had and he suggested that it was probably built this way and originally ran an un ballasted coil or someone had converted it at some time. Is it possible that at the end of the production (which this car is) they did this?

So I set off home and it started ok, got stuck in the rush hour traffic between Harrogate and Bradford and the queue for the resurfacing and arrived home safely. Parked it up on the road whilst I opened the gates and garage and moved the MG so I could get it in. It would not start. Left it a while still no go. Felt the new coil it was hot. Left it a while longer and eventually it started with difficulty but once it was running it was as sweet as a nut.

So is it fuel vaporisation or the coil. Is the voltage of 14.41 put out by the alternator causing nearly 11v at the coil the problem when the engine is running. When its not running its 6V. Chris said it should be ok but 9v is what he would like to see max and that old alternators as they wear put out higher volts.

Should I change the alternator or go back to looking at ways to reduce the heat under the bonnet or both? Or just give up and live with it? That doesn't appeal by the way.

Bob

[Howard81]

Late cars had the ballast resistor built in to the loom. No idea where it is, when my car was converted to a non-ballasted type it was connected up to feed 12V directly from the fusebox. You should check again to find out exactly how your coil is wired and if in doubt run a new 12V feed.

However, I recently had a brand new coil give me bother on the MG. The car had hot start problems and ran rough when warm. The brand new Lucas DLB105 had partially broken down inside and would only play up when hot. Removed from the car it rattled when shook! It was the really gold coil (earlier ones were pale gold). The replacement Intermotor sports coil has been perfect.

[Jon Tilson]

I had a green 1300 on a W plate and I fitted that with a britpart module.
I didnt need to do anything to it ballast wise. I dont think it was ever ballasted and still used its original
Lucas coil IIRC.

Sadly the guy I sold it to has since sold it on again and I'm not able to see what it has.

I suspect your car has a waxstat jet and its leaning out too much for an easy start. Waxtstats are prone
to over leaning when the engine bay gets warm, as you just experienced.

Next time pull the choke out and see if it starts then. I know its counter intuitive to have choke on a warm engine, but it drops the jet and will richen it enough to start.

You will get there...

Howard is talking about a Sprint that those do have a ballast wire in the loom.

Jonners

[RobSun]

If you look at my last post, help with fuel vaporisation, you will see that the coil is a new ballasted coil to suit the electronic ignition wired up seperatly from the fuse box with a ballast resistor supplied with it, because of my concerns about the old coils supply giving 12v and not the 6v expected. The wiring circuits I have seen for this model show a ballast resistor wire and a 12v supply from the soloniod. Mine has neither just a 12v supply now not used.

The waxstat jet has been changed for a red jet. Timing is set at 10° fuel used is super unleaded 97RON and the mixture set this week with a colour tune and passed the emisions today. The engine runs as sweet as a nut and was commented on by the tester and the garage owner who broke off working on a DB7 to talk to me about it and invite me to show it at an event he runs.

Today it had its longest run and the weather was hot and I was in a bit of conjestion for some of the run and a mile or so of heavey conjestion just before home and I am back to square one with no real ideas left.

Bob

[Jon Tilson]

Hmmm...
Starter switch or solenoid?

Can you get some measurements at coil plus when attempting to start and its not starting?

Also lift the lid on the float chamber next time it doesnt start. Could the fuel be evaporating when its
left hot?

Jonners

[RobSun]

Hi Jon

I have asked my son to give me a hand to crank the engine whilst I check the voltage but a rock star lifestyle isn't always condusive to helping dad out, He has to find a window but a neighbour may be able to help later this week.

I did check the float chamber recently when it wouldn't start and it was full pretty clean and the jet was clear. The fuel filter I fitted recently is also clear. At the same time I took a plug out and that was dry, I expected it to be wet due to cranking it over a fair bit, so that was the reason I was suspecting fuel vaporising in the carb.

A chap I know who is a motorcycle restorer and wants to buy this car off me cause he had a few dollies and says the 1300s the best (and I'm getting tempted) has suggested it could still need the cold start circuit fitting to cure it. He says there may not be enough umph at the spark to hot start it. What do you think? There is a spare connector on the solenoid that I was going to check if its live under cranking only and if so connect from there to the coil +ve.

The other thing is how hot should a coil get. This new one felt quite hot to me when it wouldn't start. Is this new coil duff. Should I look at doing away with the ballasted coil and get a 12v unballasted and put that in.

As soon as I can get a second pair of hands I will check those readings and all suggestions to cure this will be great fully accepted.

Bob.

[Jon Tilson]

I've taken generally to running a straight 12v coil unballasted on all my cars with electronic ignition.
The ballast bypass feed on slant cars from the starter often goes dodgy.

Jeroen is inclined to disagree and likes the ballasted bosch coil.

Ive had good cheap results with denso coils from scrap micras and almeras which are fine at a fiver
a go from a local scrappie but may now be getting a tad scarce.

Something esle you can try is next time you have the fault, hot wire the coil direct from battery plus. If it starts you know its the switching.

Jonners

[RobSun]

My son made a surprise visit last night so I got him to give me a hand checking out the spare contact on the solenoid. It was quite dirty indicating it may never have been used but it is only live giving out 10.8v when the starter is cranking. I therefore intend to clean this up and run a short wire from it to the +ve terminal on the coil sometime this week unless somebody says not to. Its possible that I will not test it out on a longish run to get it hot until next week after the Tour de Yorkshire cycle race has finished. (Traffic and road closures round the area)

Can anyone advise on how hot a coil should get, I thought they should be warm. This new one was not much cooler than the old one when it wouldn't start so could it be faulty.

Thanks Bob

[Edin Dundee]

Bob, where are you?
It would be much easier if you get a friendly member to check this out for you.

[RobSun]

Hi Bill

I'm in west Yorks. Toledo man and I have discussed the prob and a cooling issue which i sorted and thought it was fuel vaporising at the west yorks meetings. There's usually only Dave and I at them but I'm sure we will talk about it next week.
I am in touch with a couple of members via pm's also.

I am sure I will get there in the end, tomorrow I will do the cold start wire and go from there.

[MIG Wielder]

M

Can anyone advise on how hot a coil should get, I thought they should be warm. This new one was not much cooler than the old one when it wouldn't start so could it be faulty.

Thanks Bob

Hi Bob, As promised I checked out my 1850 coil this morning. After a 10 mile run in 55 degF air temperature,my coil was "barely warm to touch". So about 40 degC I reckon. It is a non-ballasted 12V Intermotor unit with a Lumenition optronic ignition system.
HTH,
Tony.

[RobSun]

Thanks tony

I haven't got a temp probe on my multi meter but warm is what I expected and not hot as it was. So this new coil could be dodgy. I will try to borrow a temp probe off someone.

Today I wired up the cold start and it fires up instantly. I have only run it up to temp in the garage and let it run a while but it restarts instantly. Before cold at best it would crank over for a second or two or need two or three turns of the key to fire so its an improvement. Now I need to give it a run preferably on a hot day. The earliest I can do this now will be Tuesday.

Tony I have sent you a couple of PM's

Thanks Bob

[Jon Tilson]

That terminal you mention is the ballast bypass feed. It should indeed be only live when cranking
and go to the coil plus.

If you have a ballasted coil how were you doing the bypass feed before?

Jonners

[RobSun]

Hi Jon

There wasn't one. The old coil only had the non ballasted yellow/white wire going to it from the wiring loom. Thats why I used the new seperate supply for the ignition to supply the new coil and its resistor so that i could be sure it was sound. If you recall I mentioned in the past a looped wire also yellow/white part of the feed wire. This was the right length to reach the solenoid but just looped to the coil positive. I can only assume that either this car was never fitted with a ballast resistor wire or it has broken down so that full volts passes along it. The contact for the cold start on the solonoid looks like it had ever been used. I also assume that at some time in the recent past a ballasted coil which is the correct spec for the car was got from Rimmers and this failed due to too high a current passing through it.

I'm hoping its now sorted but only a good test drive will tell. Also concerned that this new coil could be faulty as it was very hot when it wouldn't start on Friday. I have been told that my wiring to the ballast resistor and coil is OK and there is six volts at the coil when the engine is not running so I can't see why its running hot.

I will give it a run next week and see how it goes and report back.

Bob

[RobSun]

Just to bring you up to date. I took CWL out over Baildon and Ilkly moors this pm. 30 mile round trip and when I got back stopped it for a few minutes and it restarted immediately. Left it a bit longer and it fired up again immediately, so it looks like fitting a cold start feed has sorted it out.

Thanks for all the help especially Jonners and Migwelder for their PM's

Bob.