Starting/sparking problems.

[Angus553]

Hello Everybody      Have currently got starting problems, It currently wont start and when cranking with the ht lead and spark plug to earth it doesnt spark at all or does 1 spark on the initial turn of the key and then nothing. 

Eventually got it started with a push start in gear and drove home.(not sure how as had no spark....but it worked!!)

Since then  the rotor arm trigger wheel coil and leads and spark plugs (distributor cap new and working fine without anything appearing to be worn out)  have been changed over but still the same symptoms.  It appears as though it sparks on position 2 but not position 3, where it just spins around?? some while back the spark to earth on the  accuspark electronic ignition found a path to earth where the old and new wires joined together but this was fixed but now getting the same symptoms. My thoughts are that the electronic ignition is now not working or it could be some kind of problem with the ignition barrel/switch??

If anyone has any thoughts please let me know

Thanks  Angus

 

[EXCEL V8]

To test your ignition barrel theory you could disconnect the white/red wire from the starter and the white/pink wire from the coil and look for 12v at each in both positions of the key.

Pete

[Angus553]

Hi Excel v8  Have done as you suggested although my white/pink wire is white from the barrel to the coil.(via the fuse box.)  Tested on the left hand side of coil where the white wire was and get 13.1 v on pos 2 and 12.9 on pos 3 with slight fluctuations. Does this mean the ignition is ok then? just for good measure the key has started to stick in pos 3 occasionally !!

[EXCEL V8]

Maybe the contacts are slightly pitted in the ignition barrel, but that shows that when the ignition is in the "crank" position (3) power is still getting to the coil.  Might be worth doing the same test at the coil while the car is actually cranking - see what the voltage is.

Pete

[Angus553]

Whilst cranking the voltage is around 10.5v. With the white wire disconnected im still getting 1 spark and also with the red wire disconnected as well. The red wires are the additional ones for the electronic set up.

Edited August 6, 2022 by Angus553

[Escape]

No spark when cranking can be due to the voltage drop when the starter motor spins. Especially if the coil is old and not performing as it should. Once running the alternator will guarantee a higher voltage, which would explain why the push start worked.

To eliminate the ignition, I'd put a new feed to the coil, directly from the +12V post, just for testing. Do make sure it's easy to remove to shut the engine off again.

[jonwat]

16 hours ago, Escape said:

I'd put a new feed to the coil, directly from the +12V post

Be careful if it's fitted with a 6 volt coil, you don't want to burn it out 

[Angus553]

Hi Escape and Jonwat 

 have connected a 12v feed from the battery to the left side of coil with other wires still attached, Its an accuspark 12v coil and the same symptoms occur,as in 1   spark or no spark at all.  With the new feed should it spin without turning the key? as it didnt unless the key was turned. Have fitted 2 accuspark coils both look in good condition and the result is the same. If the ignition is ok then by elimibation it has to be electronic ignition for which Ive got replacements for but a PITA to fit having done it twice previously, or the distributor(hopefully not) assuming all  replaced parts work properly of course.

[jonwat]

26 minutes ago, Angus553 said:

the ignition is ok then by elimibation it has to be electronic ignition

Sounds like it is 

[Angus553]

Thanks for all your help. Eventually came down to the inevitable conclusion it was an intermittently faulty electronic ignition. Swapped it over and hey presto ...lots of spark again.

Had to remove the carbs this time to get access so have ordered a few parts whilst its off the car to give it the once over until next time.

[Angus553]

Although the sparking issue is solved with the replacement electronic ignition and now getting lots of spark with a very exact placement of the rotor arm and trigger wheel. Have to place the rotor arm on fully and pull it back about 0.5mm to get a good spark. 1mm equals a poor spark and fully on equals no spark. This has been the case since owning the car!!

However a new problem has evolved since doing this and replacing a few carb parts as the carb was on the bench to afford better access to the distributor.

Now it starts and runs q nicely but if you rev it up over 2500rpm the rev counter goes a bit haywire and fluctuates between 500 to 5000 rpm temporarily.  The actual rpm doesn't follow the rev counter with erratic rpm(maybe a little but not a lot and with no rev counter may not notice at all??)

Have checked the connections and earths and all appears to be good via the multimeter.

Currently the trumpets and air box are off the car to have gained good access to the distributor so sounds a bit different to the usual. 

Thinking of getting a new ignition switch but obviously this problem is v annoying and does anyone have any suggestions??

Thanks Angus

 

 

 

[EXCEL V8]

You could try a direct-from-the-battery 12v feed instead of the normal supply (green wire) which has various junctions in its pathway, and check the earth/coil connections carefully.

Pete

[Angus553]

Hi Pete

On my rev counter their is 2 green connections at the back both on the 1 terminal block and a black which has a good earth and also a white one. Can both be disconnected and a direct wire connected to the green terminal? would the extra wire need to have a fuse? also can you (or anyone else) tell me where the voltage stabiliser is as I cant find it as want to check the connections on it.  Is it best to do this from in front or below in the lotus position?

From 2 other forums a fix was to change the ignition switch for a new one and also apparently there is a counter weight on the rev counter dial  needle which can move and distort the tacho readings (eg gauge out and refit it correctly). Any thoughts.

TIA Angus   

[EXCEL V8]

One of the green wires is the 12v feed which comes through the ignition switch, fuse box and via a common terminal on the voltage regulator (there is a capacitor on this terminal as well - check that it is there).  The other green is the onward feed to the voltmeter (effectively an extension of the green wire to the voltmeter).  When removing the green wires from the tacho make sure you isolate them - they will still be live.  You could use a fuse in your test wire - the one in the fuse box is 16A.  The white wire (actually white/slate) is the trigger from the coil.  The voltage stabilizer is bolted to the back of the speedo and actually uses the speedo case earth as it's own.  Pull the dash out to see it. 

Pete

[Drawfiler]

Angus, you mention moving the rotor arm up and down, if that’s the case, replace the dizzy cap as the centre carbon electrode may be worn, giving intermittent sparking.

Peter

[Angus553]

Hi excel v8 thanks for the idea. Havent tried this yet. Will do this week. (Other jobs have had to take priority, some lotus and some not)

Hi drawfiler thanks for this. After a closer inspection of the centre spring, it doesnt work as good as it should so has been replaced with a brand new one and  now getting a good spark with the rotor arm fully on. So now back to the erratic rpm problem.....there's always something.

[Drawfiler]

If the problem with the ignition is solved and you still are getting erratic rpm, I would look at these

1 are the o rings between carbs and manifold ok

2 are fuel levels ok

3 are carbs flooding, check by feeling inside the trumpets with ignition on, if fuel level is ok then check pump pressure.

4 it is just possible that you have mis assembled carb, are the gaskets and seals ok and is accelerator pump working properly

5 I assume carbs are properly balanced.

[Angus553]

Hi Drawfiler  yes have checked all your suggestions as replaced o rings and the pump diaphragm(what a pain to get the spring to sit properly) the carbs are balanced and set to 3.5 full turns. After the last set up they were set at just over 4 turns and reading around 4 on the synchronometer. 

It seems the new electronic ignition had an intermittent fault as couldnt think of anything else. Swapped over 20+ plugs 3 dizzy caps 4 rotor arms and trigger wheels 2 ht lead sets and 2 coils and still got the same problem even with spark via cranking. New dizzy cap didnt help until the new electronic ignition arrived via a phone call to accuspark who were happy to replace it as was only 2 months old. 

Everything thus far seems to work with all the combinations just about and the position of the rotor arm and trigger wheel seem to be less critical now. the ignition switch and erretic rpm gauge also now seem to be ok again.

Just need to retune the carbs as played with them but do work ok anyway.