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Weak Spark..? New Engine Won't Fire


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#1 Supersouthward87

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Posted 22 July 2014 - 08:51 PM

As title, I have a 1981 mini clubman with a 1275 implant, it has an electronic distributor and a 1.5" carb, as the title says I'm having trouble starting it, so far it's full of fluids. I've turned it over without plugs and generally got it ready to fire. Tried to start and it won't fire. Been through the ignition and it seems like it has a fairly weak spark, so I've cleaned all the connections, how else do I make a spark 'stronger'

Edit: I've read a few posts and tried a lot of checking etc, coil and all parts are fine

Edited by Supersouthward87, 22 July 2014 - 08:59 PM.


#2 cal844

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Posted 22 July 2014 - 09:08 PM

Check the wiring, what type of coil do you have(ballast or non ballast? This affects the spark if using nonballast in place of a non ballast)

See here to test coil resistance!

http://www.theminifo...es#entry2730335

#3 dklawson

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Posted 22 July 2014 - 11:38 PM

Do provide more information on the engine/car.

 

Did the engine ever run to your satisfaction of is this car new to you?

If it ran OK before, what has changed?  (Please include all changes no matter how seemingly unrelated).

Is the electronic ignition a factory or aftermarket unit?



#4 Supersouthward87

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Posted 23 July 2014 - 07:34 AM

Sorry, I was typing on my phone last night so it didn't have much detail:

 

Car is a 1981 Austin mini clubman estate 1100.

 

The 1100 gave up the ghost (beyond my diagnostic skills), it was an older style engine with a breather on the tappet housing cover and a mechanical distributor

 

I bought a 1275 off the 'bay with dished pistons, balanced crank (supposedly) and an electric distributor. The engine included cylinder head, gearbox and dizzy. It's a silver seal engine no. which is something to do with factory re-fit I think so could have a whole range of bits and pieces I guess? Ignition is a non-ballasted type, coil is correct for ignition, also checked with another coil, both with 3.5ohm resistance. I have a spark as far as coming out of the coil but it's a little weak thus far.

 

So, my theories for engine non-firing so far are as follows:

Timing is out, not sure how to adjust

Faulty distributor

 

Never heard this engine run (tempting fate I know)

Pretty sure the electric ignition is an aftermarket as it looks something like this

http://www.ebay.co.u...ff14=108&ff19=0

 

If there's any other information I'm sure i can provide :-)

 

Thanks for all the help, it's a great forum



#5 dklawson

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Posted 23 July 2014 - 11:51 AM

Thank you for the  additional information.  It is very helpful.

 

Yes, an ignition that looks like the one in your link would be aftermarket and they typically work best with standard 12V (non-ballast) coils.  With that identified we need to turn attention to the coil and its wiring. 

 

You said the coil is correct.  Confirm the coil type by marking and removing the low-tension wires on the coil and measuring the resistance across the empty coil terminals.  A standard coil will measure around 3 Ohms, a ballast coil will measure between 1 Ohm and 2 Ohms.  Let us know which type of coil you find installed.  Also note if there are any fluids leaking out of the coil.

 

Put the low-tension wires back on the coil.  Take note of their colors paying attention to the fact that colors fade over time.  Post back with what color wires are on what coil terminals.  The ignition module will have red and black wires so include them in your list of which wires are connected to which coil terminals.  (The coil terminals may be marked + and -, SW and CB, or 1 and 15 depending on the age and type of coil).  let us know what you find connected to the coil.

 

Also note if there are any other devices connected to the coil (extra wires going off to anything nearby).  Post back with your findings.



#6 Supersouthward87

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Posted 23 July 2014 - 12:51 PM

I can answer most of this straight away.

 

The resistance in the coil is 3 ohms, correct for my non-ballast setup

 

I'm a bit confused about high and low tension wires, however mine is set up as follows:

 

1x black wire from distributor to negative terminal on coil

 

1x red wire from distributor to positive terminal on coil

 

1x black & white cable from ignition module to positive

 

1x ht lead from coil centre to distributor

 

Last night I believe i set up a demo ignition by doing the following;

power to coil, central coil output to spark plug, tap a wire from the negative to an earth, spark created, was blue but a little feeble.



#7 dklawson

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Posted 23 July 2014 - 04:30 PM

1x black & white cable from ignition module to positive

 

Last night I believe i set up a demo ignition by doing the following;

power to coil, central coil output to spark plug, tap a wire from the negative to an earth, spark created, was blue but a little feeble.

 

Do you mean a white/black wire on coil (+) or on coil (-)?  In color codes, the dominant color is listed first.  Regardless, you said this wire goes from the igntion module to positive?  A picture would help but that does not sound correct for a negative earth igntion module.  Positive earth Pertronix/Aldon Ignitor modules use a black/white wire... but again... that's a positive earth module.

 

By tapping the wire between coil (-) and earth you will create a spark but since this is not being handled by the electronic igntion module you are duplicating/simulating what a set of points does.  Since you are duplicating points and there is no condenser in the circuit the spark is going to be weak.  Therefore, what you have done is confirm the coil is working.  The weak spark is not indicative of a coil problem based on how you performed the test.



#8 Supersouthward87

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Posted 23 July 2014 - 05:37 PM

Sorry about the picture but essentially, 1 is feed from battery via module, 2 is red wire from dizzy and 3 is black wire from dizzy. Red wires are on the positive side of the coil, black negative

Attached Files



#9 dklawson

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Posted 23 July 2014 - 09:24 PM

Thanks for the picture.  It is still quite unclear how you have the wiring set up.  You said:  "1 is feed from battery via module".  What do you mean "via the module"?  The color codes of the wires on the coil do not make sense.  Are the wires shown spliced onto normal Lucas color coded wires?  Can you post a clear picture of the ignition module? 

 

If your ignition module is similar to the one shown in the link you posted earlier, it should only have two wires (red and black) that exit the distributor.  The red wire goes to coil (+), the black to coil (-).  In a previous post you are suggesting 3 wires leave the distributor and go to the coil.  Again, pictures of the outside and inside of the distributor and its wiring will help.

 

For the module shown in the eBay link, for negative earth installations the module does not "power" the coil.  The red wire of the ignition module is "getting" power from coil (+) to operate its internal electronics.  The module typically has its earth connection through its mounting foot which is in contact with the breaker plate.  The black wire from the module is connected to coil (-).  It is a path to earth for current flowing through the coil.  When the module switches "on" the black wire has a path to earth much like when in your earlier tests you tapped the test wire connected to coil (-) to earth.

 

Any other wires on the coil are for ancillary and unrelated components.  For example, if you have a tachometer (Smiths RVC or general aftermarket) its sense wire will be connected to coil (-).  If you have some switched accessories under the bonnet there may SOMETIMES be an additional wire connected to coil (+).  Also, if your car originally had ballast wiring to run a ballast type coil there may be additional wires on coil (+).

 

Backing up... please give some background on this engine.  Has it ever run for you?  Your initial post suggests you recently installed this engine.  Did you see it run before installation?  If you did see the engine run before now, what has been done to it during/after the engine was installed?  And again, please post pictures of the inside and outside of the distributor to help identify the ignition module.  I am not familiar with ones that mount inside the distributor and have (3) wires.  There are some that use an external amplifier and 3 wires.



#10 Supersouthward87

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Posted 24 July 2014 - 08:09 AM

Sorry, bit garbled there.

 

The bit in the distributor has 2 wires, one red to the coil, one black to the coil. The number 1 red wire is the feed from the battery (which I decided to call ignition module, my mistake :shy: )

 

The car has always been a non-ballast setup.

 

In regards to the engine, no I haven't heard it run, bit of a gamble I know. All I have done (perhaps foolishly) is remove the 1100, change the clutch to the 1275 and drop it back into the mini...

 

In so far as I've got, it seems to turn over fine and "seems" like it just needs some combustion. I may be at the point of calling out a mechanic...



#11 dklawson

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Posted 24 July 2014 - 12:00 PM

Thanks for the information.

 

You know the engine has spark even though you are concerned it is a weak spark.  Since you have not seen the engine run, don't focus too much on that being the problem.  Make sure the other areas are also somewhat functional.

 

Assume the engine was not in good tune when removed from the last car. 

  • Set the valve clearances.
  • The engine has electronic ignition so you don't have to worry about points or a condenser, but do check the condition of the distributor cap, rotor, plug wires and spark plugs.  Replace any that show any cracking or carbon tracking.  The engine is new to you and it deserves a new set of properly gapped spark plugs if you have not already installed new ones.
  • Look at the static timing of the engine.  Most aftermarket ignitions of the type shown in your link above can be static timed.  I'll post a link below to a PDF that discusses the process.  The article is for points but in this case it doesn't matter... just follow the basic connections and procedure.
  • You probably have looked at the firing order already.  Don't take this personally but double check the firing order.  The PDF I mentioned includes information on how to check that the firing order is correct.  Succinctly, the order is 1-3-4-2 COUNTERCLOCKWISE around the cap with cylinder #1 being the water pump end of the engine.
  • Were the carbs off the 1100 or were they on the 1275 when you got it?  Carbs that sit for a long time can gum up if fuel is left in their float bowls.  If the carbs have not been used for a while they may need attention before the engine will start.

A quick screening test is to tip a thimble of gasoline down the carb throat and try to start the engine.  If the engine runs briefly and dies, you have a fuel delivery problem, not an ignition problem.  Regardless, take the steps above to get the ignition system fully sorted before moving on to the fuel system.

 

http://www.sites.goo...icTiming[1].pdf



#12 KernowCooper

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Posted 24 July 2014 - 12:19 PM

You mention Module in your commects above ? if you have the type of distributor in the picture a Lucas 65D4M then the correct coil for this distributor is a  GCL143 and has a ohms reading of 1 ohmn, if you have a standard coil connected to the system it will kill the module on the distributor. Can you confirm one way or another which you have ?

 

If its the aftermarket electronic trigger then as Doug says it appears to me wired correctly.

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Edited by KernowCooper, 24 July 2014 - 12:21 PM.


#13 dklawson

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Posted 25 July 2014 - 12:09 AM

Dave, he included a link in post #4 and discusses in subsequent posts that this is a 2-wire aftermarket type ignition.  



#14 Supersouthward87

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Posted 25 July 2014 - 09:13 AM

Mr dklawson thank you for the detailed fault finding posts, I'll go through that and check, hopefully i've just been a bit of a numpty, I have a bit of time this weekend and Jeffery shall live again.



#15 KernowCooper

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Posted 25 July 2014 - 04:43 PM

Dave, he included a link in post #4 and discusses in subsequent posts that this is a 2-wire aftermarket type ignition.  

I saw that after I posted lol






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