Cranks but won't fire...

MY SICK S3 TURNS OVER BUT JUST WON'T FIRE. It started getting tempermental with the wet weather and fired on some days in the dry but now won't fire whatever the conditions.

I have done the following so far and am at the point where I am about to buy a new coil, but on such a tight budget and keen to minimise wastage I want to make sure I have exhausted all other avenues first:

• Checked fuel is getting to the Carb
• Changed Plugs
• Changed condenser and fixed point in dizzy
• Checked HT lead from coil for spark (to body or engine block)
  • No spark from it at all. Advised ground may be dodgy as the bracket it was mounted in was really loose so ran new wire from it's body to battery -Ve (can't tighten bracket as dash blocks getting to the nuts)
  • Coil does get warm when cranking engine
  • Checked resistance across - & + terminals and it was 2.3 Ohms and from either of those to the center terminal was 6.3KOhms (the first of those readings seems a bit low based on - http://www.series123.com/UKhomepages/index101/index.html)

What do you think genii? New coil or can I service or at least check mine further or do you think there could be something else I've overlooked? There's a pint in it for anyone who helps me get this running again

I have just taken the Voltage reading from the coil. I am so confused, cold and pee'd off so hope someone clever comes along soon.

With the ignition not on at all both "-" and "+" read about 35mV
With the ignition at II (i.e. dash lights on) the "-" (connected to dizzy) goes from 200mV to 400mV (approx.) then very quickly jumps to 1.4V and starts the cycle again. The "+" terminal (from ignition) reads a steady 9.45V
With the ignition at III (i.e. cranking) the "-" reads .45xV (where the x fluctuates e.g. .451, .457 etc.). The "+" reads 6.7V.

This doesn't seem to be right to me but as stated: cold, tired, demoralised and a bit stir crazy so could some king soul lend a hand please?

Thanks,

Andy.

Just thought, when taking readings I was using coil body as the earth side of the circuit - is that the right way to do it for measuring both the terminals?

frazzled.

you should change coil ,leads including king lead ,rotor arm , cap ,condensor,points ,plugs at same time, with ignition on + side should read 12v cranking 9v, run wire from battery to + coil check - to points ,coil braket doesnt effect coil just hyolds it coil shoul only be earthed thru points ,i would say coil us but change all as wear in one will effect life of others

The guy who told me the coil earthed through its bracket was an AA mechanic. You gotta laugh.

Thanks James, I'll get the other bits I need to replace what you suggest anyway then.

I've just measured voltage again this time across the two terminals (is this right?) and it now shows 12V ign on and about 8V cranking which seems more like it. As I moved the wire on "-" it snapped off (happens all the time as all the original leads are so brittle!) so perhaps there wasn't much of a connection on that wire, might that affect it not sparking properly from the HT lead? Will recrimp and try again but losing the fight for light tonight.

Reattached and still no firing and no spark from the HT lead.

I guess I will replace the lead and all the other stuff and see if it helps, was trying not to spend any more money but perhaps the HT lead is naff.

Water247 said:

Reattached and still no firing and no spark from the HT lead.

I guess I will replace the lead and all the other stuff and see if it helps, was trying not to spend any more money but perhaps the HT lead is naff.

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so from what I gather

there is power getting to the coil
there is no spark coming out of the coil
the condensor, points etc have been checked/replaced

I would be checking the coil, and the lead.

not much else I can think of, although having said that my dad had a Valiant 225 which was extremely rough running, sometimes wouldn't start and other times was fine.

turned out to be the condensor wasn't grounded correctly, plenty of auto electricians spent hours pouring over the engine and replacing leads, how they missed the condensor I don't know.

in the end it was a 11 year old who fixed it

Well I did replace the condensor but it's the first time I've ever opened up a distributor so I may well have messed something up there or just missed an obvious fault with it. I'm out all day today (enforced break from the car before it broke my spirit ). Will get back to it tomorrow with renewed gusto and make sure I consider dizzy issues as well. ....Will update soon.

ok, so i'm after the beer....
knowing the you've been inside the dizzy, gonna start from scratch.
check yer points-

remove dizzy cap, while your there check the carbon brush in the centre inside. should protrude 1/4 inch and spring in out freely.

remove rotor arm.

assuming its a lucas dizzy, turn engine either on handle or starter untill the cam lobe pushes the red points plastic follower to its highest point. if needed, adjust gap on points by slackening the screw to base plate and levering points in / out. gap should be 10 thou or the thickness of card from the top of a fag packet lid. nip points back to baseplate.

check connection from terminal on side of dizzy, should have a sleeved braided wire going to points termination. condensor wire should also go to this point. check to two little plasic insulators on points termination for damage. if the condensor is of unknown origin and age, change it.

connect multimeter to side terminal on dizzy and battery -ve lead, set it to continuity or its beep setting. if points are still open, nowt should happen, if closed it should be beeping at you or reading close to 0 ohms. if it dont beep or shows high continuity (>2ohm) you have bad contacts on the points or a bad connection on the cabling, if it beeps all the time you have a short circuit somewhere on the cabling / insulators. rotate engine so points open and close and meter does the appropriate thing.

replace rotor arm. rotate engine till arm points to no.1 cylinder and stop when the meter goes high resistance (open circuit) or stops beeping. look at the crankshaft pulley timing mark, it should be lined up with pointer on the first of 3 lines. (first line = 6 degrees before top dead centre (btdc) second line 3 deg btdc, first line, tdc.) if not, the static timing is out. to sort this (but doubt you'll need to) rotate engine till rotor arm is just before pointing to no. 1 cylinder. now watch for the timing mark on the pulley approaching the pointer. stop turning when the first line is on the pointer. (3d btdc)
slacken the clamp on the bottom of the dizzy and carefully rotate the entire dizzy untill the points open and meter shuts up or continuity goes high. nip clamp bolt. (nb- if its not far out, there is an adjuster on the vacuum advance that will turn the dizzy baseplate. its about the 5 oclock position on the dizzy body, looking over the wing and opposite the round diaphragm with pipe coming off it)

timing an dizzy now set.

rotate engine so points are closed.

discounting the condition of your electrics, as i'm only after the beer, connect the -ve side of the coil to the dizzy terminal. check for continuity with your meter on the coil earth (yes it does need one) from the coil body to the -ve battery lead. meter should beep or show close to 0 ohm. if not, rectify problem.

wedge coil high tension lead under heater pipe running across top of rocker box. ensure there is a 1/8" (3mm) gap between the brass conductor and the rocker box. connect other end to coil output.
connect +ve side of coil to battery +ve.
using small screwdriver, manually tweak points in dizzy to open, there should be a quick healthy crack sound and blue spark from the ht lead to rocker box. this should also be presant when turning over on starter. if no spark, replace coil.

remove a spark plugs, check gaps. (25thou). insert plug onto plug lead and wedge under heater pipe. turn engine over, should get spark at plug. if not replace lead. repeat for all plugs and leads.
replace plugs in engine, replace leads. firing order 1-3-4-2, no. 1 on dizzy explained earlier, work anticlockwise on cap with leads.

SAFETY NOTE. should you open the points while holding / touching any ht component end with the coil powered up, you'll get a right fookin crack. (40,000 volsa ish) advisable not to touch the insulated ht bits as well.

remove temp wire from battery to coil, replace original coil feed from ignition, replace dizzy cap, replace coil lead to dizzy.

turn over on starter, should fire. if not then a fuelling issue an thats another installment.

pick what you need from above, let us know what happens.

edit. if its a ducellier dizzy, the points setup is different but the timing and testing principle is the same. lucas dizzy's have black caps that are domed, the ducellier is usually brown and nearly flat topped. if its ducellier, throw it out and get a lucas. if you really need the setup procedure for a duccelier let me know, but they are ****e.

ere water its a shame yer not local to me i could have walked you through getting this sorted personally but seriously what ngrsev if you can understand it is spot on

id be tempted to copy his post to a word document and print it off for a rough guide round it while stood at the vehicle as a reference guide

on another point to test yer coil i just get any ht lead from any plug on the dizzy and put that onto the coil with a plug in the other end then wedge the plug anywhere on the engine block it will stay to get a contact then carry a live from the ignition to the coil (wearing the good ol marrigold rubber gloves) and strike the wire on and off the live terminal of the coil watching for a good blue spark from the plug on the ht lead

note the plug will only spark when you release the live from the coil (sort of mimmicking what the points do )

if you have a decent blue (not purple /red spark ) then the coil is good

johnny curt 1 said:

ere water its a shame yer not local to me i could have walked you through getting this sorted personally but seriously what ngrsev if you can understand it is spot on

id be tempted to copy his post to a word document and print it off for a rough guide round it while stood at the vehicle as a reference guide

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cheers!

tis the beer offer, really!

likewise, if he were local, i'd go in person too.

johnny curt 1 said:

on another point to test yer coil i just get any ht lead from any plug on the dizzy and put that onto the coil with a plug in the other end then wedge the plug anywhere on the engine block it will stay to get a contact then carry a live from the ignition to the coil (wearing the good ol marrigold rubber gloves) and strike the wire on and off the live terminal of the coil watching for a good blue spark from the plug on the ht lead

note the plug will only spark when you release the live from the coil (sort of mimmicking what the points do )

if you have a decent blue (not purple /red spark ) then the coil is good

Click to expand...

Just did this and got a very small spark - so small it's difficult to tell the colour but if I had to say I would say slightly orange. Sometimes it appears noticeably blue but not often. It also only sparks when I quickly brush the + terminal, if i keep it there for a second or two then remove I get nothing. The HT lead doesn't sit well on the coil as the rubber insulator is to small for it so are these possibly symptoms of that bad conenction or a coil problem?

Whilst I await your reply I'll nip back out and crack on with Servs checklist.

Thanks for the help and offer the pair of ya. Think I need to move up norf so I can get some proppa' support

Water247 said:

Just did this and got a very small spark - so small it's difficult to tell the colour but if I had to say I would say slightly orange. Sometimes it appears noticeably blue but not often. It also only sparks when I quickly brush the + terminal, if i keep it there for a second or two then remove I get nothing. The HT lead doesn't sit well on the coil as the rubber insulator is to small for it so are these possibly symptoms of that bad conenction or a coil problem?

Whilst I await your reply I'll nip back out and crack on with Servs checklist.

Thanks for the help and offer the pair of ya. Think I need to move up norf so I can get some proppa' support

Click to expand...

sounds like the coil as got fooked with the frost or iced over during that spot of crap weather get a new coil and when yer fit the new one make damn sure theres no rust or owt where it bolts to the vehicle

johnny curt 1 said:

.....and when yer fit the new one make damn sure theres no rust or owt where it bolts to the vehicle

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So, for clarification, does the coil require earthing through it's body or not? Is that why you said the above or am I missing the point?

Water247 said:

So, for clarification, does the coil require earthing through it's body or not? Is that why you said the above or am I missing the point?

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yes.
edit. check the continuity in ohms from the coil neg to the battery neg. (ignition off) i think you might have a high resistance somewhere.
are you not trying my essay for fear of giving me beer?

nrgserv said:

yes.
edit. check the continuity in ohms from the coil neg to the battery neg. (ignition off) i think you might have a high resistance somewhere.
are you not trying my essay for fear of giving me beer?

Click to expand...

right the way a coil works is simple theres a low voltage input ( the two blades for live and neutral ) thatthe small wires go onto

now all the coil does is step thart 12 volts from them to a massive current capable of delivering a spark

this high strength current comes out of the coil as its neutral through the casing and bracket into the vehicles chassis or engine block (depending where fitted ) and its live comes out where yer plug the ht lead in

if theres a **** connection between the bracket and whatever its bolted to (this includes rust and or corroded white chalky looking **** it wont give a good spark

now to eliminate the chance of there being a bad earth to the engine try the said test but this time trap the spark plug to the bracket somehow
if it gives a small barely visible or orangey spark ( anything but thick strong blue spark ) the coil will have been water damaged or fried

this was a verry common thing with austin mini's wich had the coil fitted just behind the front grille and were verry suseptible to wet and rain when being driven (hence they used to fook up regularly )

on a series its the same thing only due to age

johnny curt 1 said:

right the way a coil works is simple theres a low voltage input ( the two blades for live and neutral ) thatthe small wires go onto

now all the coil does is step thart 12 volts from them to a massive current capable of delivering a spark

this high strength current comes out of the coil as its neutral through the casing and bracket into the vehicles chassis or engine block (depending where fitted ) and its live comes out where yer plug the ht lead in

if theres a **** connection between the bracket and whatever its bolted to (this includes rust and or corroded white chalky looking **** it wont give a good spark

now to eliminate the chance of there being a bad earth to the engine try the said test but this time trap the spark plug to the bracket somehow
if it gives a small barely visible or orangey spark ( anything but thick strong blue spark ) the coil will have been water damaged or fried

this was a verry common thing with austin mini's wich had the coil fitted just behind the front grille and were verry suseptible to wet and rain when being driven (hence they used to fook up regularly )

on a series its the same thing only due to age

Click to expand...

not entirely correct johnny!
the coil works on a back emf, which is why you get a spark when the contact breaker opens. as the current in the primary dissapears, it induces a current in the secondary, and due to the number of windings, creates a high voltage. current is very low.
oh, an its ositive an negative, on dc, not live an neutral
not nit pickin, but the bad connections as you say wont help!

edit.
thinkin about it, you,ve pretty much just descibed an ignighter coil for the likes of jetwash burners or industrial fired boilers!

nrgserv said:

yes.
edit. check the continuity in ohms from the coil neg to the battery neg. (ignition off) i think you might have a high resistance somewhere.
are you not trying my essay for fear of giving me beer?

Click to expand...

Your response was awesome mate and have it printed out. I started to work through it today but it was so cold I was struggling with the dexterity of me digits so gave in! I know you said to check the resistance from the coil body to battery -Ve which along with JohnyCurts point made me want to clarify that did earth through it's body/securing bracket, as previously JamesMartin said it doesn't earth through it's body but through the points (which made sense to me). So anyway, I tested the resistance from the coil body to battery -ve and couldn't get a reading (no path).I didn't yet check the resistance from the coil -ve terminal to the battery -ve terminal which logic says I should also do.

....So once this is done what's yer tipple??!!