Won't start

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george-reed
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Won't start

Postby george-reed » Mon Dec 04, 2017 7:08 pm

You must get this a lot but here goes, Morris Minor1960 saloon, stock 948 engine, battery strong holds charge well. Been running for quite a while then started to play up a bit, replaced the following.
Fuel pump, coil, spark plugs, ht leads, dizzy cap all worked well, then intermittently felt like running on three cylinders, changed points and condenser and ran for a bit then wouldn't start. Not able to get it started at all now, where do I begine checking the wires from the loom to the various components? Any advice gratefully received.

myoldjalopy
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Re: Won't start

Postby myoldjalopy » Mon Dec 04, 2017 10:37 pm

OK then..When you say 'it started to play up a bit' what exactly do you mean? Some more detail may help a diagnosis.
Quite possibly something simple. Having changed so many parts I would go back to basics and check for a good spark at the king lead from the coil to the dizzy. The result will then suggest further investigation.

oliver90owner
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Re: Won't start

Postby oliver90owner » Tue Dec 05, 2017 12:31 am

To make the previous advice easier.

Remove the HT lead from the distributor cap at the cap and hold it just away from a metal earth (cylinder head is a good earth), while opening the contact points with an insulated screwdriver, or similar. Points need to be closed, of course, and ignition switched on.

You should get a strong blue spark each time the points are opened and it should easily jump about, or more than, a 6mm gap. If weak and/or yellowish it will indicate a likely condenser problem (but it could be a low voltage supply). If no spark at all it may mean no supply to/from the coil (primary or secondary), points not conducting while closed, or a wiring fault.

Get back on here with the results and we can easily sort out where to check next.

RAB

george-reed
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Re: Won't start

Postby george-reed » Tue Dec 05, 2017 12:43 am

thanks, held the king lead near to cylinder head, no spark when I turned the engine over.

Nickol
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Re: Won't start

Postby Nickol » Tue Dec 05, 2017 9:53 am

I am not sure I can follow Oliver's logic of opening the contact Points with the distrib. cap off but I do know he is very knowledgable and can explain.

I personally would in the first instance just remove one sparkplug from the head and turn the engine over whilst Holding it ( with thick gloves on!) against the head to see if it Shows a healthy spark.
Gott schütze mich vorm Sturm und Wind und Autos, die aus England sind.
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oliver90owner
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Re: Won't start

Postby oliver90owner » Tue Dec 05, 2017 10:53 am

Nickol,

It is simply so much easier than cranking the engine to operate the contact points. No moving parts, so much safer. No distributor cap in position, so no chance of engine firing (were it to be cranked over).

In all ways a far better option for diagnosis. Checking for spark at a plug is, indeed, a rudimetary check. But it tells you little as to where the fault is - ie only tells you it has spark at that particular plug, or not - the distributor cap could be shorting on the other three leads! If no spark, one might still need to check the plug, the plug lead, the distributor cap, the rotor arm and contact point opening before making any sensible progress.

Starting with the king lead is good because it 'halves' the testing required (and the contact points are a clear service/maintenace area anyway, so need to be checked for operational compliance) - you can then work forward or backwards along the possible fault paths, which is far better than starting at one end and not finding the fault until the very last test (Murphy'Law).

I used to ask someone to write down a number between one and a hundred a gef the rest of the class to guess that number by asking closed questions (those with an answer of 'yes' or 'no) in less than ten questions. If the number was 99 and they started their guesses sequentially from one, two etc, they would have no chance. The question 'Is it 50 or larger?' immediately halves the possible range. Halving the range is akin to you trying to fold a sheet of paper in half,and half again, ten times - you can't do it!

RAB

myoldjalopy
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Re: Won't start

Postby myoldjalopy » Tue Dec 05, 2017 6:52 pm

Ok, so no spark at the king lead.

So........check the king lead carefully for any chafing or perishing that might cause a short. Then check all connections to the coil (not loose, not corroded etc.) and the low tension lead to the distributor. If nothing obviously amiss there then I would re-check the points gap and that they are opening and closing as you turn the engine over on the handle. If all seems good there, I would get a test bulb and check that both coil terminals (marked SW and CB.......or may be marked + and -) are live to earth (= bulb will light when connected between the terminal and earth).

Assuming both terminals will light the bulb, then remove the low tension wire from the dizzy and check this end of the wire is live to earth with the test bulb. If it is, then connect the lamp between this low tension wire and its connector at the dizzy and turn the engine with the handle (or open and close the points mnaually as Oliver90 described earlier). The bulb should then flash on and off.
Let us know the results and then we shouild be a lot further down the road to identifying the problem........ :D

Nickol
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Re: Won't start

Postby Nickol » Wed Dec 06, 2017 4:35 am

thanks Oliver!
Gott schütze mich vorm Sturm und Wind und Autos, die aus England sind.
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kennatt
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Re: Won't start

Postby kennatt » Wed Dec 06, 2017 7:36 am

so no spark at king lead to engine block,..Do you get a weak spark when you flick the points open,,,,,you should...... if not no supply to them. I see you have changed the points,,,,,,,,,,,,,,,,without being too condescending, no intention, but have you fitted them correctly , it's very easy to fit them and not fit the small isolating washer in the right place,if not then you will never get it to run. just make sure the little top hat washer is preventing the lead from touching the edge of the spring .
Sorry if you know this,probably do but easy to put wire underneath washer,done it myself many times.

myoldjalopy
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Re: Won't start

Postby myoldjalopy » Wed Dec 06, 2017 8:37 am

Its worth checking the points are fitted correctly and opening and closing but I doubt it is anything to do with the leads/insulating washer being in the wrong place. The OP says he "changed points and condenser and (it) ran for a bit". If the points were shorting out then it wouldn't have started and run at all.
In all this, we are assuming nothing else has been fiddled with (e.g. timing).

simmitc
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Re: Won't start

Postby simmitc » Wed Dec 06, 2017 8:43 pm

I'm not sure how experienced you (OP George) but you've changed quite a few bits already so I guess you're familioar with the basics, so forgive me if I start to teach Granny to suck eggs.

1) Make sure car in neutral with handbrake on.
2) Remove leads from all spark plugs and remove all plugs.
3) Remove dizzy gap.
4) Reset the points gap to 15 thou. You need to rotate the engine by hand so that the heel of the points is against the raised lobe on the dizzy shaft and set the gap at that point.
5) Remove both low tension leads from the coil.
6) Fit the king lead to the coil centre terminal and position the other end close to the cylinder head.
7) Connect a new low tension lead (any piece of wire will do) between the battery non-earthed terminal ans the SW terminal on the coil.
8 ) Do you have a multimeter? If yes then check that the CB terminal on the coil has 12 volts to it. You can also check by using a 12v lamp.
9) Connect a new low tension lead to the CB terminal on the coil.
10) Momentarily touch the other end of the CB wire to earth and then remove it. Expect a spark in two places: (a) where you touch and remove the low tension wire and (b) from the end of the king lead to the block.

These tests are designed to bypass all existing components except the coil and test that, whilst at the same time preparing to go on to the next stage and acting as a reality check on work done to date.

If you confirm results then we can go on from there. Good luck.

myoldjalopy
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Re: Won't start

Postby myoldjalopy » Wed Dec 06, 2017 11:30 pm

There are, indeed, many approaches and methods in diagnosing ignition system faults, but I do like that coil test! Very useful in those 'its never the coil' moments! :D

IslipMinor
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Re: Won't start

Postby IslipMinor » Thu Dec 07, 2017 3:48 pm

George,

Where do you live? There maybe someone close(ish) by that could give you a hand. If anywhere near Oxford I will!!
Richard



TDV102
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Re: Won't start

Postby TDV102 » Thu Dec 07, 2017 6:24 pm

Check the earth straps
Good home offered for custom splittie

george-reed
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Re: Won't start

Postby george-reed » Sat Dec 16, 2017 10:35 am

Managed to get her going, stripped down the points fitting and re-fitted, convinced that the plastic top hat on points was not isolating the connections correctly. Ran for three days without hitch at all then she has stopped again. May have to dis- assemble the points again and try again, is there any advantage / risk of adding another small isolating plastic washer to the componenets? What are peoples thoughts on fitting contactless igntions have seen them on Ebay at about £35 will this cure the problem for good?

Shropshiremoggie
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Re: Won't start

Postby Shropshiremoggie » Sat Dec 16, 2017 12:51 pm

Not dismissing the modern advantages of the electronic systems the original points have served well !! If you need another ' top hat ' to try let me know , I have plenty from old points !!! Hope you do cure the issue !

oliver90owner
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Re: Won't start

Postby oliver90owner » Sat Dec 16, 2017 2:12 pm

Before dismantling, do test to check whether it is the fault you are thinking it is. Otherwise you may still just be guessing, and changing more pieces unnecessarily.

george-reed
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Re: Won't start

Postby george-reed » Sun Dec 31, 2017 1:46 am

Fitted new electronic dizzy set up, whole unit so new leads, dizzy body, rotor etc etc. still no spark and wont start! Went back to basics, battery strong and turns engine, fuel pump running, fuel in cylinders, spark plug gaps set correctly, voltage to LT side of coil 12v. Removed number 1 plug and rocked car to TDC, positioned dizzy body in clamp and located drive mechanism inside block, rotor pointed at number 1 cylinder and re-attached the leads 1-3-4-2 anti clockwise, still no joy. Lots of head scratching, what am I missing?

oliver90owner
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Re: Won't start

Postby oliver90owner » Sun Dec 31, 2017 7:00 am

Weelll, for a start, I might repeat my most previous post! Your electronic system should be better than the tried and tested Kettering system, but the improvement, although often claimed as huge, is of the order of few percent - 10% being a good improvement, I would say. One main gain is there is no need for regular maintenance like point replacement. The only down side is when they fail, replacement is considered expensive as they are usually not repairable.

If you are sure there is no spark it most certainly will not start, whatever the state of the other systems. An engine needs air and fuel in the correct ratio, compression, and a spark at the right time, in order to run. If Any one component is missing it will not start or run.

Have you fitted the appropriate electronic unit? It will not work if of the wrong polarity variety. - and likely fry the unit!

Voltage at the coil can mean nothing. You need current as well. Volts is equivalent to water pressure in a domestic system - one can still have pressure without any flow if there is a closed valve further down the line. The rate of water flow in a house water system is analogous to current in an electrical system.

Do check that the coil supply has no high resistance joints, which will restrict the current draw to the coil. Also there must be no high resistance joints on the other side of the coil (analogous to the closed tap further down the pipe). With the Kettering system the ‘valve’ beyond the coil is the contact points.

If there is actually sparks, they may be at the wrong time. Usually because the timing was set on valve overlap, instead of on compression - 180 degrees out. Alternatively, attempting to set the timing simply by pointing the rotor is fraught with inaccuracy. You need sparks, ideally, to check that ithey occur at the right times. With the Kettering system, the points could be set as just opening at top dead centre (or the appropriate setting before TDC) and ideally then adjusted, using some form of timing light, when running.

What electronic system have you installed? They can be quite basic, ranging up to very sophisticated at the other end of the price range.

kennatt
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Re: Won't start

Postby kennatt » Sun Dec 31, 2017 8:33 am

you can get TDC both on firing stroke and exhaust,which may be what you have done,make sure the timing marks on the crank pulley are indicating TDC on firing stroke, on no one, the marks may be in line but engine could be on TDC firing stroke on number four, then check dizzy again and re set if so.I take it from your post that you have had dizzy out of engine,so above very possible. If you are unsure take rocker cover off and turn engine until you see the inlet valve on number one go down and as it comes back to the top this is TDC on firing stroke number one. You may be able to see this through filler cap .The proper way is to watch number four and when the two valves are rocking then that is TDC Number one on Firing stroke.


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