Lotus Elan

Cough, cough

PostPost by: rgh0 » Sat Jul 07, 2018 3:05 am

Sounds like you have a high resistance join in the ignition power supply somewhere to see 10.8 volts under load at the coil . If that is the voltage the Powerspark module is also seeing then it would not take much more of a voltage drop for it to stop working.

The high resistance is probably in a wiring join and it may go higher as the join heats up due to the resistance causing the miss firing

I would remove as many variables as possible by hard wiring the ignition power supply to the coil and Powerspark module from a known good supply point ( e.g. the main starter cable) and a known good chassis earth and seeing if the problem still occurs

cheers
Rohan
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PostPost by: Robbie693 » Sat Jul 07, 2018 9:47 am

Thanks Rohan,

Good idea, I'll try that. They do suggest that the ballast system is bypassed for the Powerspark so I was thinking of running a new wire from the ignition switch but you've just made me realise of course the switch could be the problem too.

So -my electrical knowledge is fleeting- if I take the feed from the battery side of the solenoid this would result in a permanently live ignition correct? If I took the feed from the other side of the solenoid would that work or only when the starter was engaged?

Robbie
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PostPost by: alan.barker » Sat Jul 07, 2018 9:54 am

The other side is only for the 12 volt feed to your ballast coil 9v for easier starting.
Alan
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PostPost by: Spyder fan » Sat Jul 07, 2018 6:30 pm

change the pump jet washers https://www.ebay.co.uk/itm/WEBER-DCOE-C ... XQI5tRh1Oh

I had this problem years ago, same symptoms.
Kindest regards

Alan Thomas
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PostPost by: rgh0 » Sun Jul 08, 2018 1:02 am

Robbie693 wrote:Thanks Rohan,

Good idea, I'll try that. They do suggest that the ballast system is bypassed for the Powerspark so I was thinking of running a new wire from the ignition switch but you've just made me realise of course the switch could be the problem too.

So -my electrical knowledge is fleeting- if I take the feed from the battery side of the solenoid this would result in a permanently live ignition correct? If I took the feed from the other side of the solenoid would that work or only when the starter was engaged?

Robbie


Yes you will have a permanent "on" ignition until you can get under the bonnet and pull the wire off the live main starter cable at the solenoid. Maybe sensible to run the wire into the cabin with a temporary switch and back out to the ignition so you can switch the engine on and off while testing in a hurry if you need to.

If that solves the problem then you need to get into the full ignition wiring circuit to find the fault. if it does not then the fault is not in the ignition wiring itself and maybe in other ignition components or carbs or fuel supply. However the 10.8 volts you measured at the coil under load suggests its in your wiring. If you do the temporary wiring setup measure the voltage under load in the same way and it should be close to the battery voltage

cheers
Rohan
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PostPost by: Robbie693 » Tue Jul 10, 2018 11:20 pm

Thanks guys,

I'll pursue the voltage drop first before looking into the fuel side and report back

Cheers

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PostPost by: Hawksfield » Wed Jul 11, 2018 8:57 am

Robbie

To my knowledge the ballast resistor on your model plus 2 was a small circular resistor attached to the + terminal of the coil with two terminals.
The wiring diagram from chassis 72050732L shows this resistor and the connections, if you would like I could scan you the section from the manual
therefor you should not find any "in the wiring resistor" on your model, look for earth and connection problems !

Good luck
Regards

John

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PostPost by: Bigbaldybloke » Wed Jul 11, 2018 10:30 pm

Remember that the power wire to the coil goes via that nasty little anti theft switch in the glove box, mine gave problems similar to your misfiring and once I’d bypassed it by soldering the wires together it sorted the problem. Check also the earth braid wire from the engine to the coil, is it in good condition and has clean connections at each end. Sounds to me like you have two problems though, ignition and fuel which combine in certain circumstances, misfiring due to ignition and hesitation and fuel smells due to carburation problems.
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PostPost by: Robbie693 » Thu Jul 12, 2018 9:11 am

Thanks both,

The car was re-wired so I think the anti-theft switch is long gone, at least I never saw it when I had the dash out last.

I have a wiring diagram and noticed the ballast which I think in reality is a small ceramic disk, as I don't have one of these I assumed it had been removed of it's ballast system, which is why I haven't until now tested for circuit resistance. At least I now have something empirical to chase rather than some random symptoms.

Once I find my missing volts I can start playing with the carbs again!

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